Past, Present, and Future of Sodium Hypochlorite in Dermatology: A Scoping Review

Abstract

Background

For over a century, dilute sodium hypochlorite (NaOCl), historically recognized as the antiseptic component of bleach, has been well established in wound care, primarily owing to its broad antimicrobial activity and ability to penetrate soft tissue and necrotic debris. NaOCl has been increasingly utilized and studied in clinical dermatology owing to its broad ranging antimicrobial, skin healing, and more recently described anti-inflammatory properties.

Objectives

This scoping review (Open Science Network; osf.io/6hyru) synthesizes current evidence of NaOCl’s applications in skin care, highlighting mechanistic insights, clinical trends, and knowledge gaps.

Methods

A comprehensive search of PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov was conducted from inception through November 2024. This review was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines.

Results

From 6959 deduplicated records, 222 studies published between 1915 and 2024 were identified for final inclusion. Four key clinical themes for NaOCl use emerged upon analysis of these publications: antimicrobial properties (n = 57), wound care (n = 64), eczematous skin disease (n = 78), and noneczematous inflammatory skin conditions (n = 23). NaOCl exhibits broad-spectrum activity against various organisms, notably Staphylococcus aureus and Pseudomonas aeruginosa, contributing to its effectiveness in treating chronically infected burns, ulcers, and other wounds. Limited studies also suggest NaOCl’s potential role in modulating critical processes that support wound repair. In addition, the anti-inflammatory effects of NaOCl have supported its utility in treating eczematous and noneczematous skin disorders.

Conclusions

Current literature provides broad and extensive evidence supporting NaOCl’s role in wound-healing, antimicrobial, and anti-inflammatory activity. However, considerable heterogeneity exists in recommended concentrations, preparation methods, and usage instructions across studies. There is a need for more randomized controlled trials and standardized protocols to better define the efficacy, safety, and optimal use of NaOCl in dermatologic practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40257-025-00999-9.

Key Points

Dilute sodium hypochlorite (NaOCl), the antiseptic component of bleach, has been increasingly studied in dermatology owing to broad-ranging antimicrobial and anti-inflammatory properties.

This scoping review synthesized the body of published dermatological evidence for NaOCl and highlighted current knowledge gaps, with four key clinical dermatologic themes emerging in the analysis: antimicrobial properties, wound care, eczematous skin disease, and noneczematous inflammatory skin conditions.

While current evidence supports a broad-reaching role for NaOCl in a variety of dermatologic disease states, lack or standardization in concentration, formulation, and clinical protocols highlights the need for additional randomized controlled trials to define the role of NaOCl in clinical practice.

Introduction

Sodium hypochlorite (NaOCl), the active ingredient in household bleach, has garnered increasing recognition for its therapeutic potential in dermatology. This widely accessible compound has held medical relevance since the 18th century owing to its notable antiseptic properties [1–3]. A buffered solution of 0.05% NaOCl, known as Dakin’s solution, was famously used on the battlegrounds of World War I (WWI) [1–3]. Without antibiotics readily available, dilute NaOCl solution became a critical agent for wound sterilization and irrigation of necrotic tissue and pus [1–3]. Although some critics attributed the success of Dakin’s solution to the wound debridement technique [1], it was evident that NaOCl also possessed therapeutic value.

Expanding access to antibiotics initially led to a decline in the use of Dakin’s solution in wound care [4]. Yet, by the 1960s and 1970s, the limited penetration of antibiotics in deeply necrotic tissues prompted renewed interest and usage of Dakin’s solution [4]. The resurgence of Dakin’s solution stimulated many investigations aimed at discovering underlying mechanistic processes and ideal therapeutic concentrations of NaOCl.

Comprehending the skin-healing properties of sodium hypochlorite (NaOCl) requires an appreciation of its underlying biochemistry and its dynamic equilibrium with hypochlorous acid (HOCl). When dissolved in water, NaOCl and HOCl exist in an equilibrium (Fig. 1) [5, 6]. Thus, dilute bleach solutions inherently contain both NaOCl and HOCl. The relative concentrations of NaOCl and HOCl mainly depend on the pH of the solution, allowing formulators to control the predominant species [5, 7, 8]. Buffers are often used in solutions to maintain the pH and stability of the equilibrium [9].

Fig. 1.

Equilibrium of bleach in water. NaOCl sodium hypochlorite

The antimicrobial properties of dilute NaOCl solutions are thought to arise mostly from the presence of HOCl, a more potent oxidizing agent than the hypochlorite ion [5, 7–9]. HOCl is a highly reactive species that can form superoxide radicals, damage cellular enzymes, and promote cell death, thereby conferring its antibacterial and antifungal properties [5, 6]. Given its potential for cytotoxicity, concentrations are tightly regulated and tested when used for therapeutic purposes [4]. In human biology, HOCl is recognized for its major role in the innate human immune defense system, driving neutrophilic destruction of microorganisms [5]. However, maintaining the predominance of HOCl not only necessitates an acidic condition but also requires precise pH monitoring, temperature control, and proper storage [5, 8, 10].

Stabilizing HOCl may be feasible, as evidenced by the availability of multiple commercial products. More recently, social medial platforms have popularized and expanded numerous over-the-counter hypochlorous sprays [11]. Stability of both NaOCl and HOCl are particularly affected by light and temperature, with no significant differences between size of container or headspace volume [12]. Although no currently published studies directly compare the stability of commercially available HOCl sprays with that of NaOCl solutions, experimental data indicate slower degradation of NaOCl relative to HOCl in comparable conditions [13, 14]. Bleach solutions (which are basic) also appear to have sufficient antimicrobial properties while being widely available and cost-effective [6].

Beyond its well-established antimicrobial activity, bleach possesses anti-inflammatory properties, broadening its therapeutic potential in dermatology [15]. In their landmark 2013 study, Leung et al. demonstrated that NaOCl could irreversibly oxidize cysteine residues on IκB kinase in human keratinocytes, inhibiting proinflammatory, nuclear factor κB (NF-κB)-dependent genes [15].The NF-κB pathway is a key signaling pathway implicated in multiple inflammatory skin conditions, including psoriasis, atopic dermatitis (AD), contact dermatitis, and even melanoma [16]. Additional studies have supported these findings and further highlighted antiaging and antipruritic effects that are mediated through modulation of DNA damage and inflammatory cytokines, respectively [15, 17].

Currently, NaOCl is incorporated into expert dermatology guidelines (namely for managing AD) and formulated into over-the-counter skin care products [18–20]. As NaOCl research expands our understanding of its antimicrobial, anti-inflammatory, and skin healing effects in clinical dermatology, an extensive review and synthesis of current evidence is needed to characterize our current understanding and highlight knowledge gaps. This scoping review is the first comprehensive review that aims to detail the past, present, and future of NaOCl in dermatology to guide research and inform the management of dermatological conditions.

Methods

Protocol and Reporting Standards

A scoping review was performed and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) [21]. The protocol was registered in the Open Science Network (10.17605/OSF.IO/KCHZE).

Eligibility Criteria

Original studies written or translated in English that investigated the utility of NaOCl on the skin were included, along with any unpublished clinical trials with available results meeting these criteria. Any studies that used NaOCl only as a control or combined with other treatments without a bleach-only comparison group were excluded. However, studies comparing NaOCl in combination with another agent (e.g., antibiotics) to appropriate comparator groups (such as using the second agent alone) were included. This review aims to investigate the applications of dilute NaOCl in dermatology; therefore, reports that studied HOCl alone, examined wounds with microbes that infected nonhuman subjects, or focused on other organs were also excluded.

Information Sources and Selection

Using specific search terms (Supplementary Table 1), Embase, PubMed, Web of Science, Cochrane Library, and ClinicalTrials.gov were searched for all available publications through November 2024.

Following deduplication, titles and abstracts were screened independently by at least two authors (C.C. and M.D.) to identify studies that met the inclusion criteria outlined above. During the second round of screening, included abstracts and full-text reports were retrieved and independently assessed for eligibility by the same authors. Studies without available full texts or abstracts were excluded. Any disagreements were resolved through discussion between reviewers and/or evaluation by a third reviewer (T.H.) to achieve consensus.

Data Collection

Authors (C.C., M.D., T.H., and DW) independently extracted data on a predetermined set of characteristics: title, country/region, setting, population, study design, study period, dermatological condition(s) of interest, and a short discussion on the key findings. Studies were placed in at least one of five categories to ensure organization of texts during data evaluation: background, mechanism of action, current clinical application, future applications in dermatology, or complications/toxicity.

Results

Overview of Included Studies

A total of 6959 records were screened for eligibility. Of the 506 selected full texts or abstracts, 484 publications were retrieved for review. After exclusion of 262 studies, 222 publications remained for final review, including published abstracts that presented original content. A flow diagram summarizing the process of retrieval and inclusion is outlined in Fig. 2; reasons for exclusions are also listed. Out-of-scope research included studies without any mention of NaOCl as well as bleach in nondermatological cases such as dental procedures, joint prosthetics, and use as a household detergent. The duplicate count exclusion also included repeated information from clinical trials, brief commentaries, and abstracts associated with published reports already selected for review.

Fig. 2.

PRISMA flow diagram [234]

Publications were categorized into four major clinical domains: antimicrobial, wounds, eczematous, and noneczematous. Given the overlap of these domains, publications that discussed more than one domain were placed into the most relevant category. A graph trending the number of published studies over time across the four domains is shown in Fig. 3.

Fig. 3.

Publications in each clinical domain over time. Two articles from 1915 and 1918 were excluded from this chart to maintain visual consistency and clarity

Antimicrobial

The antimicrobial category encompassed 57 studies, published between 1915 and 2024, that primarily addressed using NaOCl as a broad antimicrobial agent against bacteria, fungi, parasites, and maggot-related infections (Table 1) [6, 7, 22–76]. These studies included review and experimental papers that predominantly focused on pathogens associated with wound, burn, surgical site infections, or skin and soft-tissue infections (SSTI).

Table 1.

Summary of studies investigating sodium hypochlorite (NaOCl) and antimicrobial applications^a

Study, year	Study type	Microbial/disease targets	Concentration of NaOCl or preparationb	Key points
Schutze, 1915 [23]	In vitro	Staphylococcus aureus (S. aureus), Bacillus oedematis maligni	Various dilutions ≤ 0.24%	Dakin’s solution was highly effective in sterilizing spore-forming anaerobes Presence of sheep serum interfered with the efficacy of Dakin’s solution; irrigation of wounds and removal of serous fluid may be necessary prior to applying Dakin’s solution
Smith et al., 1974 [24]	In vivo, in vitro	S. aureus, Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), other bacteria	10 µg/mL, 20 µg/mL	A 15-min NaOCl bath reduced burn-wound bacteria in vivo by 78% 11 of 12 normal skin sites showed significant bacterial reduction. One normal skin site exhibited no decrease in bacterial burden post bath P. aeruginosa was the most susceptible to NaOCl in vitro, while S. aureus was the most resistant organism across all concentrations tested Acidic water (pH 5.7) enhanced NaOCl’s activity against S. aureus, K. pneumoniae, and others Alkaline water (pH 8.6) improved NaOCl’s effectiveness against P. aeruginosa and other pseudomonads
Hunter, 1983 [25]	Case series	Herpes simplex virus (HSV)	0.1%, 0.5%	31 patients with HSV were treated with topical NaOCl NaOCl helped with healing and discomfort within 5 days
Fader et al., 1983 [26]	In vitro	S. aureus, P. aeruginosa, Candida albicans (C. albicans)	0.1%, 0.5%	Split-thickness cadaveric skin inoculated with bacteria 0.5% NaOCl completely eliminated S. aureus and P. aeruginosa within 5–6 min; eliminated C. albicans within 1 min 0.1% NaOCl eliminated C. albicans in 10 min, significantly decreased S. aureus, but failed to reduce P. aeruginosa on skin
Raimer et al., 1984 [27]	Review	Malassezia furfur	Not specified	Includes NaOCl as an effective topical agent for tinea versicolor
Cotter et al., 1985 [6]	In vitro	S. aureus, P. aeruginosa, C. albicans	0.1%, 0.5%	Same cadaveric skin preparation as Fader et al. Fresh preparation of 0.1% NaOCl completely eradicated S. aureus, C. albicans, and P. aeruginosa A 24-h-old NaOCl solution reduced bacteria but did not completely eliminate it No significant skin toxicity with 0.5% NaOCl
Sadik, 1988 [28]	Review	Bacteria, viruses, fungi, spores	0.4–0.5%	Review of topical antibacterials Full strength 4–6% NaOCl effective against bacteria, viruses, and fungi but too irritative for skin or human use Diluted 0.4–0.5% is less irritating for skin
McKenna et al., 1991 [29]	In vitro	S. aureus, E. coli, Group D enterococci, P. aeruginosa, B. fragilis	0.005%	0.005% NaOCl demonstrated bactericidal activity for 4 or more days without inhibiting fibroblast activity NaOCl significantly more effective than other tested antiseptic solutions (0.001% povidone-iodine, 0.0025% acetic acid, and 0.003% hydrogen peroxide)
Feedar, 1994 [30]	Review	Streptococci, Staphylococci, Pyocyaneus microorganisms	0.25–0.5%	When full-strength Dakin’s solution is applied to an open wound, free alkali is formed, which may cause local irritation or cutaneous trauma with repeated exposure
White-Weithers and Medleau, 1995 [31]	In vitro	Microsporum canis (M. canis)	5%, 10%	Hairs from dogs and cats infected with M. canis treated with 5% and 10% NaOCl solutions for 5 min twice weekly for 4 weeks; compared with tap water control and other topical solutions Both NaOCl concentrations inhibited fungal growth after 8 treatments
Perlmutter et al., 1995 [32]	Commentary	Dermatophytes	Not specified	Topical NaOCl may be used for tinea versicolor, tinea pedis, and onychomycosis
Kaye, 2000 [33]	Review	Bacteria, fungi, viruses	0.025%	NaOCl should be used with caution owing to cell toxicity Only low concentrations (e.g., 0.025%) should be used for wound irrigation and superficial skin infections
Heling et al., 2001 [34]	In vitro	Streptococcus sobrinus, Streptococcus salivarius, Streptococcus mutans (S. mutans), Enterococcus faecalis (E. faecalis)	0.0195–2.5%	Bacteriostatic and bactericidal NaOCl concentrations ranged from 0.157 to 0.315% Bactericidal and cytotoxic effects also depended on exposure time Fibroblasts did not survive in NaOCl solution in concentrations higher than 0.01%
Hidalgo et al., 2001 [7]	In vitro	S. aureus, P. aeruginosa, E. faecalis, E. coli	0.00025–0.5%	Isolated bacteria from burn wounds of admitted patients P. aeruginosa is most resistant to NaOCl, requiring concentrations ≥ 0.5% E. Coli and S. aureus required ≥ 0.025% solutions NaOCl toxicity depends on length of exposure and concentration Cytotoxicity was dose-dependent, and total fibroblast death occurred at ≥ 0.5%
Lindfors, 2004 [35]	Case series	Aerobic and anaerobic microorganisms of wounds	0.057% (cleanser)	11 patients were either treated with antimicrobial wound cleanser (AWC) containing 0.057% NaOCl or with 0.9% normal saline (NS) After 2 weeks, the wounds cleansed with AWC showed a 100% reduction in aerobic bioburden, compared with a 33% reduction with NS 22% of wounds cleansed with AWC decreased in size, compared with 11% of wounds treated with NS None of the wounds cleansed with AWC increased in size, compared with 56% of wounds cleansed with NS.
Nahm et al., 2005 [36]	Case report	P. aeruginosa, Morganella morganii (M. morganii)	1.5%	A patient with foot intertrigo caused by P. aeruginosa and M. morganii successfully treated with 1.5% NaOCl foot soaks for 20 min each day for 7 days
Buckingham, 2008 [37]	Review	Methicillin-resistant S. aureus (MRSA)	Not specified	NaOCl baths may be effective for recurrent MRSA infections NaOCl not recommended for hand hygiene given irritation
Neely et al., 2008 [38]	Ex vivo	Multidrug-resistant organisms (MDROs) including: Acinetobacter, Pseudomonas, Klebsiella, Staphylococcus, Enterococcus	0.025%	Bacterial isolates were collected from burn patients from four geographically distinct US burn centers Many isolates were MDROs Dakin’s solution showed moderate antibacterial efficacy (33–80% susceptibility) compared with other antibacterial topicals, potentially limited by its low concentration MDROs were more sensitive to Dakin’s solution than non-MDROs (72% versus 44%)
Lipsky and Hoey, 2009 [39]	Systematic review	Vegetative bacteria, viruses, fungi, spores	0.0125%, 0.125%, 0.25%, 0.5%	The advantages of NaOCl solutions include their low cost and lack of known systemic toxicity The disadvantages of NaOCl include prolonged contact time for antibacterial efficacy, inactivation by pus, and toxicity to fibroblasts and keratinocytes
Suiter, 2009 [40]	In vitro (abstract)	MRSA	1:768, 1:1280 (stock solution concentration not specified)	Pigskin model inoculated with MRSA Alcohol-based scrub outperformed both NaOCl solutions, which were not very effective at MRSA decolonization
Alvarez et al., 2010 [41]	In vivo controlled experimental study	Healthy skin bacteria	10%	The antiseptic action of 10% povidone-iodine and 10% NaOCl on healthy volunteers were compared No significant difference was found; both antiseptics significantly reduced the number of colony-forming units when compared with the control group
McIntosh et al., 2011 [42]	In vitro	Lucilia sericata (L. sericata)	0.5%	Assessed the ability of wound cleansing solutions to kill maggots in jars Treated and counted for mortality every 24 h for 14 days; 0.5% NaOCl had the highest cumulative maggot mortality of 46%
Fritz et al., 2011 [43]	Randomized controlled trial	S. aureus, skin and soft tissue infections (SSTI)	≈ 0.005%	Participants with community-onset SSTI and S. aureus colonization in the nares, axilla, or inguinal folds By end of 4 months, treatment group given twice-daily mupirocin and daily DBB had higher S. aureus decolonization rates (71%) compared with the mupirocin-only group (56%) However, treatments did not reduce the percentage of recurrent SSTI
Heller, 2012 [44]	Review	Secondary bacterial skin infections	1/8–1/4 cup per full bathtub	Twice-weekly DBBs may decrease acute skin infections, especially when combined with mupirocin No known resistance of dilute bleach and nontoxic at dilute concentrations
Bangert et al., 2012 [45]	Review	S. aureus, MRSA	1/4–1/2 per full bathtub	Dilute NaOCl can decrease S. aureus colonization and even kill community-acquired MRSA strains Dilute NaOCl baths may help skin infections and prevent spread of S. aureus within households
Bourke et al., 2012 [46]	Prospective study (abstract)	MRSA	Not specified	Between 2010 and 2011, 2.2% of 45 pediatric patients with AD had infected or active AD lesions colonized with MRSA Similar survey showed 0% positivity in 2001/2002, 6.8% positivity in 2003, and 16% positivity in 2007 Suggests that the introduction of DBBs in 2007 may contribute to this observation
Smith and Goldman, 2012 [47]	Review	S. aureus, SSTI	Not specified	Decolonization may not reduce risk of skin infections, cites study by Fritz et al. Canadian Pediatric Society does not recommend decolonization of children with community-acquired MRSA soft-tissue infections
Madrid et al., 2012 [48]	In vitro	Sporothrix schenckii (S. schenckii)	0.125–4%	9 isolates from cases of feline, canine, and human sporotrichosis; 3 isolates of S. schenckii from environment Direct contact with NaOCl solutions demonstrated fungicidal properties NaOCl stability and thus efficacy dependent on pH and organic matter such as dirt
Chang et al., 2013 [49]	In vitro	S. aureus	≈0.0078%, 0.015%, 0.024%	Dilute bleach solutions are less effective at reducing MRSA levels on pigskin models possibly owing to organic matter Higher concentrations are more effective
Barsoumian et al. 2013 [22]	In vitro	Filamentous fungi	0.000025–0.5%	SSTIs associated with invasive fungal species can arise from combat-related wounds and injuries Broad antifungal properties exhibited at concentrations 0.0025% and above If subjected to > 3-h exposure to even more dilute concentrations at ≤ 0.00025%, fungal species were significantly reduced or eliminated Overall, concentrations ≤ 0.00025% safe for keratinocytes, fibroblasts, and osteoblasts
Lewandowski et al., 2013 [50]	Case series	Aspergillus spp., Zygomycete spp.	0.025%	Three cases of invasive fungal infections successfully treated with adjunctive Dakin’s solution in conjunction with negative-pressure wound vacuum system Dakin’s solution is important for angioinvasive fungal wound infections
Kaplan et al., 2014 [51]	Randomized controlled trial	S. aureus, SSTI	5 mL per 1 gallon ≈ 0.0079%	Children with soft-tissue skin infections were randomized to 3 months of routine hygienic measures with or without twice-weekly DBBs Within 12 months, 20.9% of the control group (routine measures only) compared with 17% of the experimental group (routine measure and bleach bath) had medically attended infection
Ong, 2014 [52]	Review	MRSA	1/4 cup per bathtub (using 6% bleach)	Recommends dilute bleach baths (DBBs) for AD with MRSA infections or MRSA colonization
Yang et al., 2017 [53]	Randomized controlled trial	Various biofilm-protected bacteria	0.125%	20 patients with chronic wounds; half were randomized to receive adjunctive 0.125% NaOCl instillation to their negative-pressure wound therapy (NPWT) Patients who received NPWT with NaOCl instillation exhibited a mean reduction of 48% in bacterial quantity Patients who received NPWT only exhibited a mean increase of 14% in bacterial quantity
Banovic et al., 2018 [54]	In vivo, in vitro	Staphylococcus pseudintermedius, coagulase-negative Staphylococcus spp., Enterococcus spp.	0.05%, 0.005%	In vitro studies demonstrated that 0.005% NaOCl could reduce genes for inflammatory chemokines, chemokine ligand-2, and thymus and activation-regulated chemokine 4 healthy dogs treated with topical 0.05% NaOCl; bacteria counts were reduced but only borderline significant (p = 0.06) when compared with tap water
Eriksson et al., 2018 [55]	In vitro	S. aureus	0.0014–0.35%	AD skin with staphylococcal infections had biofilm presence Bleach effective at inhibiting and eliminating biofilms with a dose-dependent response MIC ranged from 0.01–0.08%; MBEC ranged from 0.01–0.16% Suggest exploring higher concentrations ≥ 0.0025%, while also monitoring for skin irritation
Richards et al., 2018 [56]	Review	Invasive fungal infections	0.00025%	Fungal wound infections have a high mortality rate Diluted NaOCl is often a good adjunct for invasive fungal infections; can be applied hourly or continuously via negative wound dressing If severe, NaOCl-soaked gauze can be placed in the wound with monitoring after 24–48 h
“Bacterial skin infections,” 2019 [57]	Patient education handout	S. aureus	Not specified	Society for Pediatric Dermatology recommends DBBs or washes containing NaOCl to treat S. aureus infections on the skin
Al-Hasani et al., 2019 [58]	In vitro	S. aureus, P. aeruginosa, E. coli, K. pneumoniae, Staphylococcus epidermidis, Enterobacter cloacae	1%	Biofilm formation involved in ulcer infections and chronic wounds 1% NaOCl is more effective against biofilm than 70% ethanol solution; recommends NaOCl use alone or in combination with ethanol to eradicate biofilms
McNeil and Fritz, 2019 [59]	Review	S. aureus, SSTI	0.006%	DBBs may be a more affordable way to decrease colonization of S. aureus and improve atopic dermatitis (AD) Unclear if DBBs can reduce SSTIs and be recommended for this purpose
Antonelli et al., 2019 [60]	In vitro	Candida spp., S. aureus, P. aeruginosa, other gram-negative and gram-positive bacteria	0.0006–1.25%	Tested minimum inhibitory, bactericidal, and fungicidal concentrations of NaOCl compared with chlorhexidine and HybenX® NaOCl had antimicrobial effects against many bacterial and fungal species
McMahon et al., 2020 [61]	Ex vivo	MRSA, P. aeruginosa, C. albicans	0.0057%, 0.5%	In an ex vivo porcine model, 0.5% NaOCl showed statistically significant reduction in biofilms of MRSA and P. aeruginosa when compared with NS 0.0057% did not show significant changes
Moore et al., 2020 [62]	Quality improvement	MRSA, SSTI	1 cup per 50-gallon bathtub or 1 tsp per gallon (using 6% bleach)	Decolonization procedures (such as DBB) may be challenging to implement Barriers to successful adjunct treatment include skin irritation, smell aversion, misinformation, unclear or verbal-only instructions, and inconvenience
Collier et al., 2021 [63]	Review	S. aureus, SSTI	50 ppm = 0.005%	Ideal bleach concentrations for therapy are inconsistent Concentrations are sometimes listed out on the basis of the volume of a bathtub for simplicity, but this could be confusing as bathtubs are different sizes Using common bathtub brands, authors created a chart to help calculate the concentration of DBB on the basis of the distance from the base to the overflow valve of the bathtub
Falcone et al., 2021 [64]	Systematic review	S. aureus, P. aeruginosa	0.1%, 0.5%	NaOCl products are effective against S. aureus and P. aeruginosa biofilms Biofilms are present in 90% of chronic wounds; NaOCl products may be beneficial in wound management Exposure time and concentration should be taken into consideration in the use of such antiseptic agents
Sharara et al., 2021 [65]	Review	S. aureus, SSTI	Not specified	Mixed data on using decolonization protocols to reduce SSTIs High rates of SSTI recurrence persist even after decolonization but can still consider decolonization protocols of patients and households
Hogan et al., 2021 [66]	Randomized clinical trial	S. aureus	Not specified	Household decolonization of every household member, including pets, did not reduce SSTIs when compared with targeted decolonization of only the household member(s) with SSTI
Taleb, 2021 [67]	In vitro	L. sericata eggs infected with bacteria and fungi	0.5%	Compared with 10% povidone-Iodine and 5% chlorhexidine solutions, 0.5% NaOCl was the most effective at disinfecting eggs of L. sericata used for wound debridement
Barrigah-Benissan et al., 2023 [68]	In vitro	P. aeruginosa	0.125%	P. aeruginosa biofilms are commonly isolated in chronic diabetic wounds and are difficult to treat Evaluated 4 antiseptics solutions: NaOCl, polyvinylpyrrolidone iodine, polyhexamethylenebiguanide, and octenidine NaOCl had the best antibiofilm activity
Metcalf et al., 2023 [69]	In vitro	MRSA, multidrug-resistant Pseudomonas aeruginosa (RPA)	0.45% (gel)	Compared with other antimicrobial and wound debridement techniques, ChloraSolv® gel resulted in increased reductions of the minimal biofilm eradication concentration of MRSA and RPA
Baran and Richert, 2024 [70]	Review	P. aeruginosa	Not specified	NaOCl drops can improve green nail discoloration caused by P. aeruginosa but do not help with onycholysis
Fabrizio et al., 2024 [71]	In vitro	MRSA, carbapenem-resistant Klebsiella pneumoniae (CRKP), multidrug-resistant Acinetobacter baumannii (MDRAB), methicillin-susceptible Staphylococcus aureus (MSSA)	0.125–0.275 mg/mL	Pressure wounds are often colonized by MDROs, which can produce biofilms, leading to chronic infections and treatment failures The minimum inhibitory concentration values, ranging from 0.125 mg/mL for MDRAB, MRSA, and MSSA to 0.175 mg/mL for CRKP, demonstrated the bacteriostatic efficacy of NaOCl even at low concentrations
Mukhtar, M. and Mukhtar, N., 2024 [72]	Case report	Candida spp., other secondary bacterial, fungal, and viral infections	0.1%	4 patients with chronic interdigital intertrigo treated with trichloroacetic acid (TCA) cautery and NaOCl soaks for 6 weeks; 1 patient was treated with NaOCl soaks for 6 weeks and then TCA NaOCl in sequence with TCA cautery may be effective at treating chronic interdigital intertrigo
Orbay et al., 2024 [73]	Review	S. aureus, MRSA, Enterococci spp., P. aeruginosa, vancomycin-resistant enterococcus, other gram-negative and gram-positive bacteria	0.5%	NaOCl has broad-spectrum bactericidal activity; it induces oxidative damage of cellular components, disrupting DNA, RNA, and cell membranes in microorganisms Burn wounds are often colonized with MDROs and biofilm-producing bacteria. Biofilms protect bacteria from host immune system Colonization of burn wounds can reduce skin graft survival NaOCl may be cytotoxic at high concentrations
Rosa et al., 2024 [74]	Quality improvement	Candida auris (C. auris)	0.05% (spray and gel)	C. auris-colonized patients routinely bathed with chlorhexidine (CHG) at least once a day 22 out of 24 patients followed for a new hygiene protocol further applied NaOCl to skin of the limbs and torso, inguinal and axillary areas, twice a day after routine CHG bathing Did not appear to improve decolonization; resumed back to only using routine CHG
Stiehl, 2024 [75]	Case report	P. aeruginosa, A. baumannii, group D Streptococcus,	Not specified	A 73-year-old patient with recalcitrant pressure wounds was treated with buffered NaOCl and NS irrigation to control bacterial contamination Antiseptics may be a necessary adjunct in chronic wounds
Truong et al., 2024 [76]	Review	MRSA, SSTI	Not specified	Regular DBB recommended for bacterial skin infections in athletes; may help prevent spread to teammates and recurrence

NaOCl sodium hypochlorite, S. aureus Staphylococcus aureus, P. aeruginosa Pseudomonas aeruginosa, E. coli Escherichia coli, K. pneumoniae Klebsiella pneumoniae, HSV herpes simplex virus, C. albicans Candida albicans, M. canis Microsporum canis, S. mutans Streptococcus mutans, E. faecalis Enterococcus faecalis, AWC antimicrobial wound cleanser, NS normal saline, M. morganii Morganella morganii, MRSA methicillin-resistant S. aureus, MDROs multidrug-resistant organisms, L. sericata Lucilia sericata, SSTI skin and soft tissue infections, S. schenckii Sporothrix schenckii, NPWT negative-pressure wound therapy, DBB dilute bleach bath, AD atopic dermatitis, CRKP carbapenem-resistant Klebsiella pneumoniae, MDRAB multidrug-resistant Acinetobacter baumannii, MSSA methicillin-susceptible Staphylococcus aureus, TCA trichloroacetic acid, C. auris Candida auris, CHG chlorhexidine

^aConcentration units and preparation instructions are presented as reported in the original studies. This approach was intentionally maintained to reflect inconsistencies in the literature

^bDilutions were performed with water

Antimicrobial Properties and Cellular Toxicity

The most frequently studied organisms were Staphylococcus aureus (S. aureus), including methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa (P. aeruginosa), and Candida spp. (Table 1). Additional microbial targets included herpes simplex virus (HSV), Streptococcus spp., Enterococcus spp., Escherichia coli (E. coli), Morganella morganii (M. morganii), Enterobacter cloacae, Klebsiella pneumoniae, Malassezia spp., dermatophytes, Lucilia sericata (L. sericata), Sporothrix schenckii, Aspergillus spp., as well as other invasive fungi.

Most experiments were performed in vitro, utilizing bacterial cultures, human fibroblasts, cadaveric skin, or porcine models. Studies consistently showed effective antimicrobial properties of NaOCl. In vitro test concentrations varied from 0.000025% [22] to 10% NaOCl [31, 41]. In 1991, McKenna et al. were the first to show that concentrations as low as 0.005% NaOCl could offer bactericidal properties [27]. Nevertheless, there was a dose-dependent antimicrobial response favoring higher concentrations [6, 7, 22, 26, 49, 54, 55, 61].

In addition, some studies revealed enhanced bactericidal and fungicidal effects with longer exposure times, allowing greater microbial killing even at more dilute concentrations [7, 26, 44]. More recent studies have focused on using dilute concentrations less than 0.05% NaOCl, likely reflecting longstanding concerns regarding cytotoxicity of fibroblasts and skin irritation [7, 22, 28, 30, 33, 34, 37].

Notably, in vitro culture analyses do not necessarily translate directly when applied in vivo or even on animal skin models. For instance, the natural composition and external environment of animal skin may reduce the efficacy of diluted bleach solutions [23, 39, 49, 54]. These same factors may also protect against skin irritation, possibly mitigating cytotoxic effects as well [6, 55]. Furthermore, the pH and age of the solution also appeared to affect the efficacy of solutions [6, 24, 48].

Chronic Wounds and Burns

Over the past decade, antimicrobial applications of bleach have increasingly focused on their role in chronic, recalcitrant wounds. Ten studies have demonstrated the antibiofilm properties of NaOCl against biofilms most often formed by S. aureus and P. aeruginosa, as well as other multidrug-resistant bacteria and fungi implicated in chronic wounds [53, 55, 58, 62, 64, 69, 71–73, 75]. Biofilms are notoriously resistant to antibiotics and are associated with severe infection, contributing to the persistence of chronic, debilitating wounds. In addition, the multispectrum coverage of topical dilute NaOCl solutions may be important for burn wounds, which can harbor multiple multidrug resistant organisms (MDROs) [24, 38, 73]. Antimicrobials are essential in burn care as they improve the survival of skin grafts. As a result, dilute NaOCl solutions may serve as a necessary adjunct to control resistant bacterial contamination in burns and chronic wounds [53, 64, 75].

As seen with planktonic bacteria, the antibiofilm properties of NaOCl are dose-dependent and strain-dependent [53, 55, 61, 71]. Various concentrations were used to demonstrate these effects in vitro. McMahon et al. compared NaOCl with saline in an ex vivo porcine model [61]. They observed that 0.5% NaOCl showed a statistically significant reduction in MRSA and P. aeruginosa biofilms, whereas a lower concentration of 0.0057% failed to produce substantial changes [61]. Another study showed similar findings with a 0.45% NaOCl solution that reduced MRSA and rifampin-resistant P. aeruginosa (RPA) biofilms [69]. However, the minimum biofilm eradication concentration (MBEC) of staphylococcal strains may range as low as from 0.01 to 0.16% [55], while 0.1% NaOCl may be sufficient for other MDROs [58]. Notably, in a small randomized controlled trial carried out with 20 patients, Yang et al. showed a significant reduction of biofilm-protected bacteria using a 0.125% NaOCl intervention [53].

SSTIs and Decolonization Protocols

The well-established literature on NaOCl’s antimicrobial properties has also informed the utilization of bleach baths in the setting of S. aureus and MRSA decolonization for preventing recurrent SSTIs. Bourke et al. suggested that introducing bleach baths may account for the decrease in MRSA positivity observed in 2010–2011 surveys compared with 2007 and 2003 [46]. However, there is not enough information to evaluate the strength of this claim.

Bleach baths were often described using volume-based household dilutions (e.g., 1/4–1/2 cup of 6% bleach in a full bathtub), approximately 0.005–0.01% NaOCl. As Collier et al. pointed out, bathtubs are not standardized across households, further contributing to concentration discrepancies [63]; the “ideal” tested concentration may slightly differ.

Despite the rationale for SSTI prevention, recommendations are still in development owing to conflicting evidence. While some clinical studies have shown limited benefit [43, 66] and highlighted inconvenience [63], others have suggested that dilute bleach baths (DBBs) may reduce the recurrence of SSTIs [51, 77]. Given the high likelihood of staphylococcal recolonization, some have argued for an entire household decontamination protocol [65]. However, in one randomized controlled trial, Hogan and colleagues demonstrated that a complete household decontamination protocol, including pets, was not more effective in preventing 1-year SSTI recurrence compared with a standard decontamination protocol of the affected individual [66].

Wounds

Overall, 64 studies focused on the use of dilute NaOCl in the management of wounds (Table 2) [1–4, 9, 77–135]. The publication years ranged from 1918 to 2024, reflecting a longstanding interest in understanding the mechanism of action, expanding applications, and safety profile in wound treatment.

Table 2.

Summary of studies investigating sodium hypochlorite (NaOCl) and wound healing^a

Study, year	Study type	Cellular/mechanistic targets	Concentration of NaOClb	Key points
Austin and Taylor, 1918 [77]	Ex vivo	Skin irritation and hypersensitivity	0.48%	Wounds on rabbit ears treated with chloramine-T or 0.48% Dakin’s solution NaOCl was more effective in debriding necrotic tissue compared with chloramine-T but caused more irritation to healthy tissue
Whitehouse et al., 1976 [78]	Controlled trial	Skin irritation and hypersensitivity	5.25%	Hypochlorite-bleached diapers caused less severe diaper irritation than non-bleached diapers
Parks et al., 1977 [79]	Review	Burn wounds	1:120 (stock solution concentration not specified)	Dilute NaOCl can be used for antisepsis in burn wounds
Wright, 1978 [80]	Commentary	Burn wounds Skin grafts	Not specified	Diluted NaOCl can be used as a general antiseptic for well-grafted skin or skin that is excised but not yet grafted skin NaOCl applied as “a drip” on small areas or by immersion for larger wounds
Bunyan, 1983 [81]	Review	Burn wounds	0.05%	NaOCl reacts with wound proteins to form chloramines, which have bactericidal and bacteriostatic properties NaOCl solutions cleanse wounds and reduce edema, inflammation, and pain 0.05% NaOCl successfully reduced the infection rate in burn patients
Slahetka, 1984 [82]	Case series Commentary	Ulcers	1:3 (stock solution concentration not specified)	3 cases of patients with ulcers treated with Dakin’s solution dressings Dakin’s solution led to ulcer disinfection, debridement, and size reduction; also stimulated growth of granulation tissue NaOCl promotes blood flow in ulcers, supporting the healing process
Lineaweaver et al., 1985 [83]	In vitro, in vivo	Fibroblast viability Antimicrobial (Staphylococcus aureus)	0.05–0.5%	Using 0.5% and 0.025% NaOCl led to 0% fibroblast survival 0.005% concentration of NaOCl achieved complete bacterial eradication while maintaining high fibroblast viability (97% survival), indicating it as a safe and effective dilution In vivo murine model showed that 0.5% NaOCl delayed wound healing and reduced the strength of the wound
Cardany et al., 1985 [84]	Interventional clinical trial	Burn wounds	120 µg/mL, 240 µg/mL, 780 µg/mL	The addition of NaOCl to hydrotherapy tanks used for burn treatment significantly reduced the number of bacteria on burned and unburned sites compared with sterile water hydrotherapy tanks; however, NaOCl led to patient discomfort
Kozol et al., 1988 [85]	In vitro	Fibroblast viability Neutrophil migration	0.0025–0.00025%	0.0025–0.00025% Dakin’s solution led to > 90% inhibition of neutrophil migration. 30-min exposure to 0.025% and 0.0025% Dakin’s solution resulted in significant fibroblast toxicity
Raffensperger, 1989 [9]	Correspondence	Wound	Not specified	Criticizes Kozol et al. for relying on in vitro studies to guide clinical management Higher concentrations of NaOCl are necessary for in vivo skin tissue and wounds owing to inactivation from organic matter Hypochlorous acid (HOCl) is the antimicrobial species in diluted NaOCl; can act as a broad-spectrum antimicrobial without concern for resistance at this time
Brantley et al., 1990 [86]	Review	General wounds Inactivation	0.25–0.5%	NaOCl can be inactivated by organic matter and alterations in pH NaOCl has demonstrated efficacy and toxicity at different concentrations in in vitro studies
Swaim, 1990 [87]	Review	General wounds	0.125–0.25%	Dakin’s solution has antimicrobial activity and can liquify necrotic tissue At high concentrations, it can damage tissues and wound-healing cells, and cause discomfort
Heggers et al., 1991 [88]	In vivo, in vitro	Fibroblast viability	0.007%, 0.0125%, 0.024%, 0.25%	0.0125% NaOCl had fibroblast viability similar to control 0.025% NaOCl maintained fibroblast cytoarchitecture and viability 0.25% NaOCl led to cell death and morphologic disruption of fibroblast cytoarchitecture 0.25% and 0.025% NaOCl were bactericidal; 0.0125% NaOCl was bactericidal for gram-positive organisms only 0.025% NaOCl is the optimal concentration to retain both wound healing and antibacterial properties
Cooper et al., 1991 [89]	In vitro	Fibroblast and keratinocyte viability	≈0.0016–0.125%	Study suggested reduced fibroblast viability at higher NaOCl concentrations, whereas lower concentrations promoted increased viability Keratinocytes are more sensitive than fibroblasts to NaOCl exposure
Phillips and Dover, 1991 [90]	Review	Fibroblast viability	0.005%	Dakin’s solution can be toxic to fibroblasts, but at lower concentrations, it maintains antibacterial activity and fibroblast viability
Haller, 1992 [2]	Review	Historical use	Not specified	Dakin’s solution requires aseptic and antiseptic precautions throughout administration to be successful Treatment proved to be very successful in stationary hospitals with sufficient staff, while treatment results fell short in less resourced environments
Catlin et al., 1992 [91]	Review	Fibroblast viability Collagen deposition	Not specified	NaOCl solutions shown to interfere with fibroblast activity and collagen synthesis; also associated with skin irritation
Kjolseth et al., 1994 [92]	In vitro	Angiogenesis and neovascularization	0.25%	In 16 wounded mice, only half showed signs of epithelialization or neovascularization following treatment with 0.25% NaOCl Rate of epithelialization was significantly slower compared with the control group
Doughty, 1994 [93]	Review	General wounds	0.25%	Dakin’s solution exhibits antimicrobial properties against various microorganisms in open wounds There are conflicting opinions surrounding the cytotoxic effects of Dakin’s solution; some report concern for severe cellular damage while others report safe usage at lower concentrations
Gold et al., 1994 [94]	In vivo	General wounds Skin toxicity	0.5%, 0.25%	Hairless guinea pig lesions either exposed or unexposed to sulfur mustard; all lesions were then decontaminated with NaOCl, calcium carbonate, or water Decontamination with NaOCl solution increased visual severity of the wounds in both sulfur-exposed and unexposed skin May need to use topical NaOCl with caution
Heggers et al., 1996 [95]	In vivo	General wounds	0.025%	Several topical treatments were applied on acute excisional wound animal models NaOCl healed wounds significantly faster than the untreated control group NaOCl-treated wounds had significantly higher breaking strength than the control group, suggesting stronger, better-healed tissue
Goffin et al., 1997 [96]	In vivo, ex vivo	Stratum corneum	4%	15 women with healthy skin each received 5 patches of 4% NaOCl and 5 patches of deionized water (control) Pairs of control and NaOCl patches were removed at 15, 30, 45, 60, and 90 min to assess exposure lengths There were no clinical signs of skin irritation or significant changes in transepidermal water loss (TEWL) at NaOCl sites for all time points NaOCl induced a significant reduction (p < 0.05) in skin capacitance after 60 min, which lasted for 24 h after 90-min exposure The squamometry index significantly increased with the NaOCl formula patch, while remaining unchanged with the water patch. This change, indicating structural weakness, was most pronounced 24 h after patch removal and returned to baseline within a few days 4% NaOCl contact can modify the stratum corneum without affecting the skin barrier
Hidalgo and Dominguez, 2000 [97]	In vitro	Fibroblast viability	0.00025–0.5%	Low concentrations of NaOCl (0.00025–0.005%) stimulated growth of fibroblasts. Higher concentration of NaOCl (> 0.05%) led to total cell death for cultured human fibroblasts
Bennett et al., 2001 [98]	In vivo	Fibroblast viability Collagen deposition Angiogenesis	0.25%	5 topical agents, including 0.25% Dakin’s solution, were applied to 12 porcine incisional wound models After 4 days, NaOCl significantly increased fibroblast proliferation (p < 0.05) After 7 days, wounds treated with NaOCl exhibited a significant increase in neodermal thickness compared with the control group (p < 0.01). There were no significant changes in angiogenesis or collagen production compared with the control
Thomas, 2001 [99]	Review	Ulcers	0.05%	0.05% Dakin’s solution was inferior to hydrocolloid dressings in the treatment of pressure ulcers
Vu et al., 2002 [100]	In vitro	Burn wounds	0.025%	Tested various antimicrobial agents on 126 gram-negative and 79 gram-positive bacteria isolated from burn victims Dakin’s solution and bacitracin exhibited a significant reduction in antimicrobial efficacy compared with other agents
Beitz, 2005 [101]	Review	Necrotic tissue Skin irritation	Not specified	Discusses several methods of wound debridement Dakin’s solution can help debride necrotic tissue slowly and lower microbial count Can be toxic or irritating to healing tissue
Doughty, 2005 [102] (dressings)	Review	Necrotic tissue debridement Inactivation	0.025%	0.025% Dakin’s solution has broad-spectrum bactericidal effects, promoting the dissolution of necrotic tissue and aiding in odor control NaOCl should be kept away from heat and light to avoid deactivation Dressings with Dakin’s solution must also be changed twice daily
White et al., 2006 [103]	Review	Fibroblast viability Neutrophil activity	Not specified	Modified NaOCl solutions might reduce safety concerns and maintain therapeutic benefit in wound treatment
Bruch, 2007 [104]	Book chapter	Skin irritation and hypersensitivity reactions	0.5–0.6%	0.5–0.6% NaOCl is generally well-tolerated and effective in treating chronic wounds and burns NaOCl can cause mild irritation or delayed-type hypersensitivity reactions, especially with prolonged contact or at high concentrations
Iwai and Hirao, 2008 [105]	In vivo	Stratum corneum and skin hydration	0.15%	NaOCl solution applied to forearms for 10 min twice over 2 days NaOCl-applied site had more protein carbonylation and reduced water content in the stratum corneum
Vick et al., 2008 [106]	In vitro	Fibroblast migration Collagen degradation	0.5%, 0.25%, 0.125%, 0.0125%	NaOCl has a dose-dependent effect: higher concentrations increased collagen degradation and inhibited fibroblast migration Viability of collagen and fibroblasts also depended on exposure time 0.0125% exhibited little to no collagen degradation and preserved fibroblast viability, making it an ideal concentration Adding fetal calf serum (to mimic real clinical environment), improved survival; in vivo analyses need to be carried out
Cornwell et al., 2010 [107]	Case series	Granulation tissue Necrotic tissue Ulcers	0.05–0.5%	5 cases of various chronic wounds treated with Dakin’s solution 0.05–0.25% led to granulation tissue development 0.05% promoted wound closure 0.125% reduced wound area and volume 0.25% led to rapid debridement of necrotic tissue 0.5% decreased odor and was used as part of a palliative treatment plan
Altunoluk et al., 2011 [108]	Retrospective cohort study	Fournier’s gangrene	0.025%	14 patients with Fournier’s gangrene were reviewed After stabilization, they were either treated with daily povidone-iodine dressings or NaOCl dressings Mortality rate was lower in the NaOCl group, though without statistical significance Hospitalization time was significantly shorter in the NaOCl group
Coetzee et al., 2012 [109]	In vitro	Fibroblast viability Antimicrobial	0.003%, 0.006%, 0.0125%, 0.025%	0.003%, 0.006%, 0.0125%, and 0.025% unbuffered NaOCl resulted in 98.9%, 88%, 86.2%, and 24% fibroblast viability, respectively NaOCl’s minimum bactericidal concentrations for Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes were 0.003%, 0.006%, and 0.0015%, respectively 0.006% NaOCl is the optimal concentration for management of burn wound infections
Cardile et al., 2014 [110]	In vitro	Cellular toxicity	0.25–0.00025%	Dose-dependent toxicity of NaOCl solutions tested on murine models; concentrations between 0.025% and 0.25% affected macrophage function and survival 0.00025% Dakin’s solution may be safe, but more in vivo testing required
McCullough and Carlson, 2014 [111]	Background article	Historical use Fibroblast viability Neutrophil activity	0.05%	Henry Dakin tested over 200 compounds until he finally buffered 0.05% NaOCl with boric acid, creating Dakin’s solution. Dakin’s solution has been shown to have high germicidal activity with minimal toxicity Antiseptics should primarily be used in the inflammatory phase of wound repair, as cells mediating the proliferative or regenerative phase of healing (such as fibroblasts and neutrophils) are adversely affected by them Dakin’s solution can be used successfully for certain cases with appropriate concentrations
Sabbatani and Fiorin, 2017 [1]	Review	Historical use	Not specified	Septic complications were the cause of high mortality rates during WWI Dakin’s solution improved mortality rates
Norman et al., 2017 [112]	Systematic review of randomized controlled trials	Burn wounds	Not specified	Low-certainty evidence from a single trial (10 participants, 20 burns) suggests that NaOCl may slightly reduce healing time when compared with silver sulfadiazine (SSD) Mean difference = −2.10 days (95% confidence interval [CI] −3.87 to −0.33). Evidence downgraded owing to imprecise data results
Kramer et al., 2018 [113]	Review	General wounds	< 0.06%	NaOCl is effective against various bacteria, viruses, and spores in vitro and enhances wound healing at certain concentrations NaOCl preferred in treating contaminated acute and chronic wounds
Ueno et al., 2018 [4]	Review	Historical use	0.005%, 0.025%, 0.5%	Historical context of Dakin’s–Carrel technique that treated infected wounds on the battlegrounds; involved constant irrigation with Dakin’s solution Despite growth of antibiotics, Dakin’s solution remained important owing to its ability to penetrate necrotic tissue and offer broad-spectrum antimicrobial effects Dakin’s solution may also form chloramines, offering additional bactericidal effects However, its use was controversial since higher concentrations led to cell toxicity and impaired wound healing; using a more dilute solution such as 0.025% may still confer antibacterial properties
Hawk, 2019 [3]	Review	Historical use	Not specified	The Carrel–Dakin technique involved removing debris and wound debridement, followed by dilute NaOCl irrigation of the wound, aiming to sterilize and dissolve remaining necrotic tissue NaOCl effective at reducing gas-gangrene infections and preventing amputations
Slaughter et al., 2019 [114]	Review	Skin irritation and hypersensitivity	Not specified	Side effects are minimal and transient with brief exposure to NaOCl Prolonged exposure or higher concentrations can lead to hypersensitivity reactions and chemical burns Skin should be flushed with water if exposed
Georgiadis et al., 2019 [115]	Review	Chronic wounds Surgical site infections Bacteria and fungi	0.0125–0.05%	Review of NaOCl applications in chronic wounds, surgical site infections, and bacterial or fungal infections Ideal concentrations for wound healing differ between in vitro and in vivo studies, possibly owing to inconsistencies in preparation of the solution
Ottesen et al., 2020 [116]	Case series	Granulation tissue	0.5%	3 cases of wounds treated with Dakin’s solution (0.5% NaOCl) All wounds formed granulation tissue with treatment and either closed spontaneously or closed with secondary intention without infection
da Costa et al., 2021 [117]	In vivo	Collagen deposition Angiogenesis Neutrophil activity	4%	NaOCl yielded a significantly higher percentage of wound repair, accelerated cutaneous wound closure, and exhibited proangiogenic activity It also significantly increased neutrophil activity after 3 days of treatment, while significantly decreasing neutrophil activity after 7 days Furthermore, type III collagen increased after 7 days of treatment, while type I collagen increased after 14 days
Ambrose, 2021 [118]	Review	General wounds	0.45–0.5%	Dakin’s solution is an effective antiseptic for infected wounds; however, it loses antimicrobial potency within 1 h of application; NaOCl must be replaced every 2 h until the wound is sterile
Babalska et al., 2021 [119]	Review	Necrotic tissue debridement Skin irritation and hypersensitivity	5–10%	At concentrations between 5% and 10%, NaOCl has been observed to cause skin irritation and necrosis. Allergic reactions and dermatitis may also occur Tissue necrosis occurs in a concentration-dependent manner. At concentrations higher than 10%, NaOCl is corrosive to the skin and eyes Patients with hypersensitivity to NaOCl may experience swelling, pain, and respiratory issues
Eliasson et al., 2021 [120]	In vivo pilot study	Necrotic tissue debridement	0.45% (gel)	ChloraSolv® gel creates a moist, alkaline environment that helps loosen and dissolve necrotic tissue
Chung et al., 2022 [121]	Review	Skin irritation and hypersensitivity	Not specified	NaOCl may trigger contact dermatitis Severity of irritation depends on exposure time
García-Valdivia et al., 2022 [122]	In vitro	Skin grafts Fibroblast and keratinocyte viability	0.02%	Antiseptics are important for preventing infections in skin grafts Various antiseptics were studied on bioengineered autologous skin substitutes to investigate cell viability, cytokine secretion, and epidermal barrier function NaOCl had the highest cell-viability rate; no significant changes in TEWL or proinflammatory cytokine release
Ortega-Llamas et al., 2022 [123]	In vitro	Fibroblast viability	1%, 0.057%	1% dilution of NaOCl did not affect cell viability compared with other treatments 0.057% NaOCl demonstrated trending recovery of fibroblasts after 24 h of treatment
Serena et al., 2022 [124]	Prospective, randomized, double-blind pilot study	Chronic wounds	0.057%	15 patients received daily wound cleansing with either normal saline (NS) or 0.057% NaOCl After 4 weeks, the percentage of area reduction of wounds was 71.8% in the NaOCl group compared with 21.3% in the NS group Fluorescence imaging was used to track bacterial load. The NaOCl group exhibited a 25–75% reduction in fluorescence compared with 0–25% in the NS group
Jaber et al., 2022 [125]	Randomized controlled trial	Diabetic ulcers	0.1%	Patients with diabetic foot ulcers received antibiotic therapy, surgical debridement, and irrigation with either NS or 0.1% NaOCl Upon discharge, patients in the NaOCl group were also given commercial Clorox® and instructed to soak their ulcers in a diluted 0.08% Clorox® bath every other day. Patients in the intervention group had significantly fewer amputations and hospitalizations along with significantly faster rate of total ulcer closure compared with the control
Konschake et al., 2022 [126]	Randomized controlled trial (abstract)	Skin grafts	Not specified	Evaluated NaOCl containing wound gel to treat split thickness graft survival (STGS) Treatment group had less pain and quicker epithelization
Liao et al., 2022 [127]	Retrospective case-series	Skin grafts	0.025%	59 patient cases with mainly lower extremity wounds were reviewed Compared STGS in three groups: Bolster dressings Continuous negative-pressure wound therapy (NPWT) only Continuous NPWT interrupted at 48–72 h for Dakin’s solution and reapplied Greatest STGS survival with Dakin’s solution
Quiñones Vico et al., 2023 [128]	In vitro (abstract)	Fibroblast and keratinocyte viability	Not specified	NaOCl was least detrimental to fibroblasts and keratinocytes compared with other antiseptics
Maniscalco et al., 2023 [129]	In vitro	Neutrophil activity	0.05%	Human macrophages were treated with an antiseptic solution containing 0.05% NaOCl Observed a reduction in matrix metalloproteinase (MMP) release with treatment MMPs can cause proteolysis and slow wound healing; NaOCl may help wound healing
Alihosseini et al., 2023 [130]	Review	Necrotic tissue debridement Ulcers	0.5%	Dakin’s solution is used to treat venous leg ulcers; it contains chlorine, which reacts with water to form HOCl—a germicidal, bacteriostatic agent that dissolves necrotic tissue Dakin’s solution can be cytotoxic at concentrations > 0.025%
Champagne et al., 2023 [131]	Case report (abstract)	Adverse effects	0.25%	A 20-year-old patient treated with 0.25% NaOCl solution after being struck by a motor vehicle Phosphate levels began to rise 1 month after admission; authors suggest the increased risk of hyperphosphatemia when used in an immobilized patient with multiple bone fractures, blood transfusions, vitamin D deficiency, hypoparathyroidism, and wound debridement
Buta and Donelan, 2024 [132]	Review	Historical use Skin irritation and hypersensitivity reactions Inactivation	Not specified	Prior to the 20th century, NaOCl was used as a disinfectant but contained free alkali or chlorine, causing skin irritation Henry D. Dakin and Alexis Carrel refined NaOCl and developed a protocol for its use in the treatment of wounds and burns. This protocol became very commonly used and successful in military hospitals during WWI Dakin’s solution is still limited by its rapid inactivation, low wound penetration, and local toxicity
Mayer et al., 2024 [133]	Review	Necrotic tissue debridement Antimicrobial	Not specified	NaOCl can react with fatty acids and proteins to soften necrotic tissue, aiding in wound debridement It can also kill bacteria, viruses, fungi and spores by creating an alkaline and oxidative environment that destroys pathogens and biofilms
Ringblom et al., 2024 [134]	Systematic review	Ulcers	0.08%, 0.1%, 0.7%	Several studies discuss various wound cleansing methods in the treatment of diabetic foot ulcers 0.7% chloramine solution (NaOCl + amino acids) decreased time to healing and reduced ulcer surface area. NaOCl treatment resulted in greater wound closure
Guest and Apelqvist, 2024 [135]	Retrospective cohort analysis	Venous leg ulcers	0.45% (gel)	ChloraSolv® gel delivers NaOCl to wounds and has been effective in the treatment of venous leg ulcers, increasing the probability of healing in venous ulcers after 24 weeks

NaOCl sodium hypochlorite, HOCl hypochlorous acid, WWI World War I, TEWL transepidermal water loss, SQMI squamometry index, NS normal saline, STGS split thickness graft survival, MMP matrix metalloproteinase, NPWT negative-pressure wound therapy

^aConcentration units and preparation instructions are presented as reported in the original studies. This approach was intentionally maintained to reflect inconsistencies in the literature

^bDilutions were performed with water

Historical Use and Preparation

During WWI, septic complications were the leading cause of mortality among wounded soldiers [1, 2]. Developed by Henry Dakin and Alexis Carrel [111], the Carrel–Dakin technique involved a method of wound debridement followed by continuous irrigation with dilute NaOCl—one of the most commonly used antiseptics during the war [1–4, 132]. It was particularly effective in treating gas gangrene wounds and preventing amputations [3]. Even with the expansion of antibiotic therapies, the use of Dakin’s solution remained prominent owing to its penetrative abilities and broad-spectrum antimicrobial properties [4]. However, Dakin’s solution was not without its detractors, given its association with cellular toxicity and risk of impaired wound healing [4]. In addition, its success depends on aseptic technique, and reduced efficacy has been observed in low-resource conditions [2]. In general, over time, optimized formulations and concentrations have led to fairly widespread adoption of NaOCl for wound debridement and healing in routine clinical practice.

Wound-Healing Processes

Full-thickness wound healing generally progresses through four stages [89, 107]. The first stage of healing is hemostasis, followed by the inflammatory phase (i.e., second stage), which promotes phagocytosis of bacteria, breakdown of necrotic material, and the release of growth factors [93, 111]. Polymorphonuclear leukocytes and macrophages are essential cell types in the inflammatory phase [93, 111]. The third stage of full-thickness wound repair is the proliferative phase [93, 111], including granulation tissue formation, wound contraction, and epithelialization [89, 107]. Fibroblasts, endothelial cells, and keratinocytes play essential roles in the proliferative phase; they are critical to the formation of connective tissue, angiogenesis, and epithelialization, respectively [93, 111]. Lastly, the maturation phase consists of scar-tissue remodeling with collagen deposition and breakdown [93, 111]. Three of the four stages—inflammatory, proliferative, and maturation—can be modulated by NaOCl in several ways [93, 111].

Optimal wound healing requires adequate preparation of the wound bed. The presence of necrotic tissue and other materials in wounds creates barriers to healing and reduces the efficacy of wound-healing treatments [101, 102, 120, 133]. They can prevent the healthy migration of cells, tissue formation, and neovascularization. Thus, debridement is necessary for wounds to heal and close [101, 102, 120, 133].

Six studies have explored the role of NaOCl in the debridement of necrotic tissue [101, 102, 119, 120, 130, 133]. They found that NaOCl not only exhibits antimicrobial properties but also reacts with fatty acids and proteins to soften and dissolve necrotic tissue [101, 102, 130, 133]. It also promotes necrotic tissue lysis [102, 120]. However, these therapeutic benefits must be balanced with NaOCl’s cytotoxic potential, as tissue necrosis has occurred after exposure to high concentrations of NaOCl [79].

Neutrophils are a key cell type involved in the first stage of wound healing, the inflammatory phase. In response to NaOCl treatment, neutrophil activity exhibits a concentration-dependent response. Across three clinical studies, NaOCl concentrations tested ranged from 0.00025% to 4% [85, 117, 129]. In an in vitro wound model, low concentrations (0.025–0.00025%) of Dakin’s solution inhibited neutrophil migration and deactivated chemotactic factors necessary for neutrophil recruitment [85]. In contrast, an in vivo study demonstrated that wound treatment with a chlorinated solution derived from 4% NaOCl showed increased neutrophil activity on day 3 and decreased it on day 7 [117]. This modulation supports early wound healing while preventing prolonged inflammation during later stages.

Another in vitro study further investigated the effects of a 0.05% NaOCl solution on the release of matrix metalloproteinases (MMPs) [129]. The authors found that NaOCl reduced the extracellular release of MMPs from monocyte-derived macrophages. Given that MMPs exhibit proteolytic properties and impair wound healing, these findings suggest that NaOCl may promote an environment favorable for wound healing [129].

Macrophages also play critical roles in the inflammatory phase of wound healing [111]. One in vitro study found that concentrations of Dakin’s solution between 0.025% and 0.25% negatively impacted macrophage function and survival [110]. However, lower concentrations were found to be less cytotoxic and potentially safe for wound treatment; macrophages also respond to NaOCl in a concentration-dependent manner.

Fibroblasts produce connective tissue, a key element of the proliferative phase [93]. However, researchers remain concerned about the detrimental effects of NaOCl on fibroblast viability and activity, which often occur in a concentration-dependent manner [93, 103]. In six in vitro studies [83, 85, 88, 89, 106, 109], the tested concentrations of NaOCl ranged from 0.0025% to 0.5%. At higher concentrations, NaOCl treatment generally led to a decrease in fibroblast viability and migration [83, 85, 88, 89, 106, 109], and higher concentrations of NaOCl also led to a reduction in keratinocyte viability [89].

In contrast, five studies demonstrated that NaOCl either maintained or increased fibroblast viability in a concentration-dependent manner [89, 89, 90, 98, 123]. Tested concentrations ranged from 0.000025% to 0.25%. At lower concentrations, NaOCl treatment generally led to an increase in fibroblast viability [89, 97]. Additional studies have also shown that NaOCl is the least detrimental to fibroblasts and keratinocytes compared with other widely used antiseptic treatments, such as povidone-iodine [122, 128].

In two separate case reports, Dakin’s solution also appeared to stimulate granulation tissue in wounds [107, 116]. Angiogenesis and neovascularization, additional key processes of the proliferative phase, can be modulated by NaOCl [111]. One in vivo study found that NaOCl exhibits proangiogenic properties at high concentrations (4%) [117]. However, other clinical studies reported that NaOCl yielded no significant changes in angiogenesis or neovascularization after treatment with 0.25% NaOCl [92, 98].

The impact of NaOCl on extracellular matrix remodeling has also been investigated. Four studies examined collagen deposition in response to NaOCl treatment, with mixed findings [91, 98, 106, 117]. In one in vivo murine study, treatment with 4% NaOCl promoted an increase in type I and type III collagen deposition in wounds after 14 and 7 days, respectively [117]. Conversely, high concentrations of NaOCl led to increased collagen degradation in vitro [106]. Other studies have found no significant change or even inhibition of collagen production in wounds, interfering with and delaying healing [91, 98].

Clinical Applications

Topical NaOCl has shown promise in skin healing for various types of wounds. NaOCl-soaked gauze dressings have successfully been utilized in the treatment of Fournier’s gangrene. One randomized clinical trial found that NaOCl dressings significantly reduced hospitalization time in patients with Fournier’s gangrene [108]. The antimicrobial and wound-debridement properties of NaOCl have also led to its frequent use in the treatment of ulcers, where it contributes to infection control, necrotic tissue removal, circulation optimization, and granulation tissue formation [82, 107, 124, 130, 135]. NaOCl has also shown clinical benefits in ulcer healing rates, surface area reduction, and closure [82, 107]. Serena et al. found that a 0.057% modified NaOCl solution yielded a significantly greater percentage area reduction in patients’ ulcers and wounds compared with standard saline solution [124]. Moreover, a randomized controlled trial found that using 0.1% Dakin’s solution significantly improved ulcer closure, reduced hospitalizations, and decreased amputations [125]. However, NaOCl appears to be inferior to hydrocolloid dressings in treating pressure ulcers [99].

In burn treatments, NaOCl has been successful owing to its antimicrobial properties [79]. NaOCl solutions react with wound proteins to form chloramines, which exhibit bactericidal and bacteriostatic properties [81]. This mechanism is emphasized in clinical studies that show a reduction in microbial loads, specifically in burn wounds [84], with similar antiseptic effects to other compounds such as silver sulfadiazine and mafenide acetate [100].

NaOCl may also alleviate pain and inflammation associated with burns [81]. One study reported a reduction in burn wound healing time compared with silver sulfadiazine, though this study was downgraded to low-certainty evidence owing to imprecise results [112]. Others have reported that NaOCl induces patient discomfort [84] or causes skin grafts to slough off if used on areas with low integrity [80].

Beyond burns and ulcers, NaOCl has also shown promise in treating excisional wounds and skin grafts. In acute excisional wound animal models, NaOCl intervention resulted in significantly faster healing rate and break strength when compared with an untreated control group [95]. Georgiadis et al. showed that irrigation of surgical sites with 0.0125% Dakin’s solution reduced the rate of surgical site infection by half in post-mastectomy patients with surgical drains [115]. NaOCl solutions have outperformed other antiseptics in the treatment of contaminated acute and chronic wounds [113] and may also be highly effective for skin graft management, improving both skin graft survival and tolerability [122, 126, 127].

Clinical Considerations and Adverse Effects

NaOCl antimicrobial activity in wounds may lose potency rapidly, potentially within 1 h of treatment [118]. Therefore, it is recommended that Dakin’s solution be frequently replaced for optimal treatment [118]. However, stronger concentrations of NaOCl are associated with cytotoxicity, patient discomfort, wound severity, and damage to wound-healing cells [86, 87, 94]. Skin irritation, contact dermatitis, and necrosis have been reported, particularly at higher concentrations and longer exposure times [77, 101, 104, 114, 119, 121]. When first introduced as a disinfectant in the 19th century, bleach solutions were found to cause skin irritation owing to the presence of free alkali or chlorine [132]. Subsequent refinements were made to create Dakin’s solution, which reduced irritants; however, cutaneous side effects have remained a concern [132]. Interestingly, one clinical trial found that diapers treated with NaOCl (using 5.25% Clorox^® solution) caused fewer cases of severe skin irritation in babies than non-bleach diapers [74]; the concentration and formulation of NaOCl may thus be a determinant of its safety profile.

NaOCl has also been associated with modifications to the skin barrier. One study found that NaOCl increased protein carbonylation and water content of stratum corneum (SC), indicators of skin barrier disruption [105]. Another study revealed that while the 24-h squamometry index (SQMI) of skin increased upon application of NaOCl, SQMI returned to baseline after several days, and there were no significant changes to transepidermal water loss (TEWL) or clinical signs of skin irritation [96]. A single case report showed an increased risk of hyperphosphatemia with NaOCl use for wound treatment, though this occurred in a complex clinical scenario with other associated factors [131].

Clinical utility of standard formulations of NaOCl may be limited by rapid inactivation, given susceptibility to degradation by organic matter, changes in pH, and heat and light exposure [9, 86, 102, 132]. Therefore, NaOCl should be stored and handled carefully to preserve its therapeutic benefits.

Atopic Dermatitis

In total, 78 publications discussed the use of dilute NaOCl in the context of AD (Table 3) [5, 8, 18, 19, 136–180, 180–208]. Publication years spanned from 2008 to 2024, a period marked by growing interest and expanding use of DBBs for AD.

Table 3.

Summary of studies investigating sodium hypochlorite (NaOCl) and atopic dermatitis (AD)^a

Study, year	Study type	Concentration(s)	Exposure time, frequency	Key points
Krakowski et al., 2008 [136]	Systematic review	1/4–1/2 cup per 40-gallon bathtub (using “common bleach solution”)	5–10 min, 2–3 times a week	NaOCl may reduce the amount of skin infections and bacterial colonization in AD; however, it can cause skin irritation; avoid NaOCl in those who have contact allergy
Krakowski and Dohil, 2008 [137]	Review	1/4 cup in bathtub	5–10 min, 2–3 times weekly or as specified by physician	Patients with AD predisposed to bacterial colonization and skin infections Exacerbations may be linked with Staphylococcal aureus (S. aureus) proliferation—supported by clinical response to antistaphylococcal antibiotics Dilute bleach baths (DBBs) could potentially play an adjunctive role in reducing bacterial burden and preventing infections
Wollenberg and Schnopp, 2010 [138]	Case series	Not specified	Twice weekly	Exact mechanistic role of bleach remains unclear Routine antimicrobial treatments not recommended; they do not offer long-term effectiveness
Paller, 2012 [139]	Review	0.005%	Not specified	Studies that used mupirocin and bleach together still demonstrate the therapeutic effect of bleach, as only the areas exposed to bleach showed clinical AD improvement DBB are generally safe and should be used as maintenance treatments
Paller et al., 2012 [140]	Review	0.005% ≈ 1/4 cup per half-filled 40-gallon bathtub ≈ 1/2 cup per full bathtub ≈ 3 cc per gallon (using 6% bleach)	Not specified	DBB should be used for maintenance for S. aureus suppression
Tan and Gonzalez, 2012 [141]	Review	1/4 cup per half-filled bathtub ≈ 1/2 cup per full bathtub	Twice weekly	DBB may be helpful for kids with frequent flares as well as history of staphylococcal infection and/or colonization
Barnes and Greive, 2013 [142]	Review	One “capful” per full bathtub up to 1 cup per quarter-filled bathtub	Refers to instructions by Krakowski et al. Up to 20–30 min	Bleach favored for its accessibility, low cost, and tolerability Bleach decomposes readily; concentration of bleach varies even with the same commercial bottle depending on its manufacture date and environment Bleach can cause irritant dermatitis or worsen asthma Commercial bleach may have additional irritants and additives; Milton’s sterilizing fluid 2% is an NaOCl solution without any additives No standardized or ideal DBB regimen
Gotsiridze and Siegfried, 2013 [143]	Retrospective, observational cohort study (abstract)	Not specified	Not specified	S. aureus colonization associated with AD severity and more DBB usage Prior mupirocin usage associated with mupirocin-resistant strains No association between streptococcal colonization and DBB use
Leins and Scullin, 2013 [144]	Randomized controlled trial (abstract)	Not specified	3-month duration	3 months of DBB reduced severity of AD when compared with emollient baths
Mackenzie and Schofield, 2013 [145]	Review	0.005% ≈ 1/2 cup (120 mL) per full bathtub (150 L) (using 5–6% bleach)	Not specified	Despite lack of evidence, many clinicians still recommend DBB, especially in patients with secondary infections
Nguyen and Zuniga, 2013 [146]	Review	1/4–1/2 cup in water (not specified)	10 min, twice weekly	DBB may prevent secondary skin infections and postpone more aggressive treatments
Ryan et al., 2013 [147]	Open-label, nonrandomized trial	(wash)	1–2 min application of wash, 3 times a week for 12 weeks	18 children with moderate-to-severe AD older than 6 months with lesional cultures positive for S. aureus were treated with NaOCl body wash for 12 weeks After treatment, AD severity measured by Investigator Global Assessment (IGA), and affected body surface area (BSA) decreased significantly Parents rated body wash easier to use than DBB 3 children reported irritation, with 1 dropping out of the trial before completion; rest improved
Swanson and Canty, 2013 [148]	Review	0.005% ≈ 1/4 cup per bathtub (using 6% bleach)	Daily DBB for 5 days or 5–10 min, twice weekly for 3 monthsc	Reviewed published studies supporting the bleach treatment for SSTIs and AD
Wong et al., 2013 [149]	Randomized controlled trial	100 mL in 100 L of water ≈ 50 mL in 50 L of water (using 6% bleach)	10 min, twice weekly for 2 months	DBB clinically improved AD within 1 month compared with water bath (placebo) Significant reduction in Eczema Area and Severity Index (EASI), itch scores, and affected BSA compared with placebo There was reduction in S. aureus colonization at 1 and 2 months but did not eliminate colonization entirely Mild drying, stinging, and burning with NaOCl This study was not controlled under supervision; people were directed to make their own DBB at home
Aslam et al., 2014 [150]	Review	0.005%	Not specified	Evidence for DBBs is limited
Bohaty et al., 2014 [151]	Open-label trial, pilot study (abstract)	0.0061% (gel)	Not specified	24 participants with moderate-to-severe AD and confirmed S. aureus colonization Daily cleansing with a NaOCl wash for 6 weeks reduced itch and EASI scores
Lee and Van Bever, 2014 [152]	Review	0.005–0.009%	Refers to instructions from Ryan et al. and Wong et al.	Published research investigating DBBs are of lower quality, and blinding is difficult given strong bleach smell Antiseptics can be a good adjunct to AD therapy, but unlikely to replace them completely Bleach efficacy could arise from altered skin microflora, rather than just reduction of S. aureus
Paller, 2014 [153]	Review (abstract)	Not specified	Not specified	DBBs reduce AD severity and risk of infection
Gupta, 2015 [154]	Review	0.005% ≈ 1/4–1/2 cup per 40-gallon bathtub (using 6% bleach)	1–3 times a week	DBBs reduce S. aureus colonization and have anti-inflammatory properties by inhibiting the nuclear factor κB (NF-κB) pathway Start DBBs few weeks after acute flare as eroded areas may sting; spray bottle may be used
McGowan and Jacob, 2015 [155]	Nurse education sheet	1/4–1/2 cup per bathtub (using 6% bleach)	10 min, 2–3 times a week or as recommended by provider	Bleach decreases bacteria on skin and reduces inflammation
Mohan and Lio, 2015 [156]	Review	Not specified	Not specified	Expert guidelines for DBBs are not consistent between US and other parts of the world 2014 guidelines from American Academy of Dermatology recommend bleach for decolonization of S. Aureus 2013 Joint Task Force on Allergy–Immunology views bleach use as promising but emphasizes more research 2012 European Guidelines state that bleach is useful for reducing AD severity 2012 Asia–Pacific Guidelines recommend DBB only for patients with AD with secondary skin infection
Shi et al., 2015 [157]	Randomized controlled study (abstract)	0.005%	10 min	6 mild-to-moderate participants with AD randomized to receive DBBs or water baths DBBs increased stratum corneum pH in patients with AD, but there was no change in corneometry or transepidermal water loss (TEWL)
Chong and Fonacier, 2016 [158]	Review	1/4 cup of bleach in full bathtub	Daily for 5 days followed by twice-weekly baths	DBBs should be considered as adjunctive therapy for patients with high bacterial colonization
Galli et al., 2016 [159]	Italian Consensus Statement article	(bath or wash)	Not specified	Recommends adjunctive DBBs; may be helpful for secondary bacterial infections
Gonzalez et al., 2016 [160]	Randomized controlled trial	0.005% bath ≈ 1/4 cup per half-filled bathtub ≈ 1/2 cup per full 40-gallon bathtub ≈ 1/2 tsp per gallon of water if using a baby bathtub (using 6.15% bleach)	Twice weekly for 4 weeks	Low microbial diversity and high relative S. aureus density was associated with higher AD severity Lesional AD skin had higher total bacterial load and greater S. aureus density compared with nonlesional and healthy skin Treatment with corticosteroids (TCS) alone was compared with treatment with TCS and DBBs. Skin microbiome of lesional skin resembled nonlesional skin in both groups. No significant differences in EASI scores between groups Suggests no additional clinical benefit or microbiome changes from adding DBBs to TCS regimen
Grey and Maguiness, 2016 [161]	Review	1/2 cup of 6% per full bathtub or 1/4 cup of 8% per full bathtub or 1–2 tablespoons per infant bathtub	Daily DBBs for 2 weeks	Consider DBBs for S. aureus colonization and infection, since it has no known antibacterial resistance Effects from DBBs are both antimicrobial and anti-inflammatory
Hon et al., 2016 [162]	Randomized, cross-over trial	0.005% ≈ 83 mL per 100 L of water (using 6% bleach)	10 min, 2–3 times weekly, 4 weeks	Cross-over trial comparing twice-weekly DBBs for 4 weeks and water baths for 4 weeks; included a 4-week washout period No significant difference in reducing S. aureus between groups or improving Children Dermatology Life Quality Index (CDLQI), skin hydration, TEWL, blood eosinophil count, total IgE Water baths significantly improved SCORAD when compared with bleach Water baths may be equally—or possibly more—effective than DBBs for treating AD
Shi et al., 2016 [163]	Randomized controlled trial	0.005%	10-min soak	10 patients with mild-to-severe AD compared with 10 healthy controls Both groups had similar increase in skin pH, stratum corneum hydration, or TEWL when forearms were submerged in bleach and water baths; this lasted for 15 min before returning to baseline There was no statistical difference in mean hydration, TEWL, and pH between groups
Chopra et al., 2017 [164]	Systematic review and meta-analysis	0.005% DBB 0.0061% cleanser	5–10-min, 2–3 times weekly for 1–2 months	Systematic review of 5 studies investigating efficacy of bleach; included Ryan et al., Wong et al., Gonzalez et al., and Hon et al. Concluded that bleach is associated with improvement in AD severity but may not be advantageous over water baths
Gittler et al., 2017 [165]	Review	0.005%	5–10 min, 2–3 times per week	Mixed evidence and recommendations regarding efficacy and clinical relevance of bleach While DBBs may be recommended in settings of recurrent infections in AD, they may not be more effective than topical steroids or simple water baths
Prezzano and Beck, 2017 [166]	Review	Not specified	Twice weekly	Current literature lacks long-term, randomized controlled trials on DBBs as monotherapy, bleach efficacy comparison between patients with AD with and without colonization, when to prescribe antimicrobials in AD, and antibacterial clothing
Stein Gold and Eichenfield, 2017 [166]	Review	1/2 cup per full bathtub or 1 teaspoon per half gallon in a water spray bottle	≥ 3 times a week for severe AD or recurrent infections	DBBs can be effective for both inflammation and infections Severe AD or those with recurrent infections should use DBBs or spray
Sim et al., 2017 [167]	Case series (abstract)	Not specified	Depending on AD severity: daily for 1 week, followed by 2–3 times a week or twice weekly from the beginning	For 12 weeks, 15 out of 21 patients with mild-to-severe AD received DBBs After intervention, there were statistically significant reductions in Dermatology Life Quality Index (DLQI), EASI, itch, and bacterial swab growth density
Thomas and Fernández-Peñas, 2017 [168]	Review	Not specified	Twice weekly for 3 monthsc	S. aureus density greater in lesional AD skin; higher densities associated with higher AD severity
Eberting and Rundle, 2018 [169]	Case study (abstract)	Not specified	Not specified	While DBBs reduce S. aureus colonization, they also increase skin pH, which can hinder lipid production, activate inflammatory pathways, trigger contact dermatitis, and interfere with epidermal cell turnover
Kusari et al., 2018 [170]	Review	1/2 cup per full 40-gallon bathtub (using 6% bleach)	5–10 min, twice weekly for 3 monthsc	Reviews up-to-date literature on DBBs Despite mixed evidence, DBBs are still recommended given their accessibility and patient preference
Luzzi et al., 2018 [171]	Review (abstract)	Not specified	2–3 times weekly	Reviewed 6 prospective studies DBBs may decrease EASI scores and BSA in moderate-to-severe AD
Lee and Detzel, 2018 [172]	Review	0.005%	5–10 min, twice weeklyc	DBBs may be recommended for skin infections and reduction of S. aureus colonization
Maarouf and Shi, 2018 [5]	Review	0.005% (bath), 0.006% (wash)	5–10 min, twice weekly for 3 monthsc And refers to instructions from Wong et al., Hon et al., and Ryan et al.,	Discusses mixed literature findings on antimicrobial effects of NaOCl and its role as an adjunct NaOCl does not appear to affect skin hydration and TEWL any more than tap water but does reduce itch scores and has anti-inflammatory and antipruritic effects based on mice models NaOCl may have applications in radiation dermatitis given its modulation on NF-κB
Pavlis and Yosipovitch, 2018 [173]	Review	1/2 cup per full bathtub or over-the-counter wash and topical solution	5–10 min, twice weekly	NaOCl is a good adjunct when patients with AD are colonized with S. aureus DBBs also reduce itch scores and are safe when used as instructed
Rangel and Paller, 2018 [174]	Review	0.005% ≈ 1/2 cup per full bathtub ≈ 3.8 cc per gallon ≈ 1 cc per liter (using 5–6% bleach)	Refers to instructions from Wong et al. and Barnes et al.	AD exacerbation is related to skin dysbiosis and S. aureus overgrowth S. aureus releases toxins and superantigens, inducing inflammation, skin barrier disruption, and increased allergen sensitization DBBs are effective for AD control and can be used daily for more recalcitrant areas May need to consider decolonization of the entire household and pets
Vakharia and Silverberg, 2018 [175]	Review	Not specified	Not specified	DBB benefits mainly come from the water—not NaOCl Hypochlorous acid (HOCl) is also more reactive than NaOCl with promising studies in AD
Asch et al., 2019 [176]	Retrospective cohort study	Not specified	Not specified	Studied whether bathing additives such as bleach or acetic acid could reduce 1-year systemic antibiotic use in children with AD superinfection There was an overall increase in bath additives between 2000–2005 and 2009–2014 cohorts, but no attributable reduction in systemic oral antibiotic usage with introduction of DBBs or any other additives
Brar et al., 2019 [177]	Review	Not specified	Twice weekly for 12 weeksc	Mechanistic role of bleach is uncertain given mixed evidence in literature Common side effects of DBBs are xerosis and irritation
Briscoe et al., 2019 [178]	Retrospective cohort study	Not specified	Not specified	Out of 118 pediatric patients with AD with positive aerobic bacterial cultures, DBB usage did not significantly affect MRSA prevalence, and 60% of patients did not have information on DBBs
Chan and Ong, 2019 [179]	Review	Not specified	Not specified	Discusses growing debate and reconsideration regarding the role and efficacy of DBBs DBBs may still be helpful for certain groups of patients with AD with recurrent infections
George et al., 2019 [180]	Systematic review with meta-analysis	0.005%	Not specified	Little to no short-term benefit of DBBs in symptom improvement or quality of life when compared with placebo (water or bath emollients) especially in uninfected patients with AD Minor side effects reported, including burning, stinging, and dry skin There is inadequate evidence to support anti-staphylococcal interventions for both infected and uninfected patients with AD
Kim et al., 2019 [181]	Review	Not specified	Not specified	Abnormal skin barrier function in patients with AD predisposes them to S. aureus colonization and related infections S. aureus colonization is associated with greater TH2-driven inflammation, increased disease severity, as well as superficial and soft-tissue infections DBBs may be effective in AD management
Majewski et al., 2019 [182]	Prospective, open-label trial	(wash)	Daily wash for 6 weeks	50 pediatric participants with moderate‐to‐severe AD used 0.006% CLn body wash daily After 12 weeks, there was significant improvement in primary and secondary clinical outcomes, including severity, itch, and quality of life Significant reduction in TSC use by week 6 61% with prior DBB usage preferred wash formulation Mild side effects such as transient burning and warmth Of note, participants remained colonized with MSSA or MRSA after intervention
Sawada et al., 2019 [183]	In vitro	0.005%	Not applicable	0.005% NaOCl concentration did not kill or inhibit S. aureus on agar, broth cultures, or pig skin Typical DBB concentrations are not antimicrobial; other properties of bleach, such as anti-inflammation, may be more significant in therapy
Thompson, 2019 [184]	Case reports (abstract)	1.2 mL per 1 L of water in a spray bottle or soaked facial cloth	Spray wiped off after 5 min	If bathtubs are not available, spray bottles and soaked facial cloths were effective for two pediatric cases
Vestergaard et al., 2019 [185]	European guidelines	Not specified	Not specified	DBBs are safe in pregnancy
Wernham et al., 2019 [186]	Review	Not specified	Not specified	DBBs provides no additional benefit for reducing AD severity and S. aureus colonization
Chng and Yew, 2020 [187]	Systematic review	Not specified	Not specified	Nail changes in AD can be exacerbated by NaOCl
de la O-Escamilla and Sidbury, 2020 [188]	Review	1 tsp per gallon of water up to 1/4 cup per full bathtub	5–15 min, twice weekly	DBBs used to decrease skin infections and improve AD severity Use DBBs for maintenance rather than acute flares
Tasker et al., 2020 [189]	Review	Not specified	Not specified	Combination treatment studies make it difficult to isolate bleach effects Bleach use is controversial
Khadka et al., 2021 [190]	Randomized, prospective, nonblinded trial	0.006% ≈ 1 mL per L (using 6% bleach)	10–15 min, twice weekly for 3 months	28 children with moderate-to-severe AD and 14 healthy controls followed for 3 months Randomized to receive emollients and TCS treatment with and without DBBs Relative abundance of S. aureus correlated positively with AD severity When AD severity improved with treatment, S. aureus abundance also decreased, resulting in levels similar to those in healthy controls DBBs significantly reduced S. aureus compared with treatment group with emollients and TCS alone Supports differences in microbiome and severity in patients with AD treated with DBBs
Narla and Silverberg, 2021 [191]	Review	1/2 cup per full bathtub or 1/4 cup per half-filled bathtub	10 min	DBBs may not be more effective than water baths Current evidence supporting DBB as an adjunctive is weak
Takieddin, 2021 [192]	Review	1/2 cup per full bathtub	10 min, no more than twice weekly	Recommends DBBs for AD maintenance and decrease in bacteria colonization
Bakaa et al., 2022 [193]	Systematic review with meta-analysis	0.005% ≈ 1/4–1/2 cup per full bathtub (using 5–6% bleach)	10 min, 2–3 times per week	In patients with moderate-to-severe AD, there is moderate-certainty evidence that DBBs reduce AD severity Low-certainty evidence indicating that DBBs may minimally reduce AD colonization with S. aureus No significant changes in patient-reported outcomes, including itch, sleep quality and quality of life, in very-low- to low-certainty evidence reports
Krynicka and Trzeciak, 2022 [8]	Review	0.005–0.006% solution ≈ 100 mL per 100 L of water (using 5–6% bleach)	5–10 min, 2–3 times per week	The mechanism and antimicrobial effects of NaOCl in setting of AD is disputed; complete eradication of S. aureus may not be necessary Dilute NaOCl may confer anti-inflammatory properties, while being affordable and well-tolerated
Paller and Beck, 2022 [194]	Editorial	0.005–0.006%	Twice weekly	More recent evidence demonstrates NaOCl’s anti-inflammatory properties on skin, leading to indirect microbial changes
Sharma et al., 2022 [195]	Review	0.005%	15 min, twice weekly for 3 months	Dilute NaOCl may be an affordable, effective adjunct for patients with AD without evidence of antimicrobial resistance In the context of India, DBBs are not widely accepted owing to high humidity year-round
Wollenberg et al., 2022 [196]	European guidelines	0.005%	Not specified	24/24 experts agreed on recommending antiseptic drugs, such as 0.005% NaOCl, for patients with AD with recurrent skin infection
Huang et al., 2023 [197]	In vitro	0.005%	Not applicable	NaOCl pretreatment of keratinocytes inhibited NF-kB and reduced serine protease expression, which are associated with skin barrier function and itch Therapeutic mechanism of NaOCl more likely related to its effect on inflammation and skin barrier integrity
De Benedetto et al., 2023 [19]	Canadian guidelines	1/2 cup per full bathtub, 1/2 cup per half-tub or 1 tablespoon per 4 gallons of water for infant bathtubs	10 min, 2–3 times a week	DBBs recommended for patients with moderate-to-severe AD; not recommended for patients with mild AD Limited data available to make DBB recommendations and provide mechanistic understanding
Mohta, 2023 [198]	Case–control (abstract)	Not specified	3 months	48 participants with AD compared with 16 healthy controls Compared standard treatment with and without DBB Lower abundance of S. aureus in DBB group Relative abundance of S. aureus correlated with AD severity
Ong et al., 2023 [199]	Commentary	0.007–0.009%	15 min, twice weekly for 3 months	0.005% concentration of NaOCl not effective for S. aureus eradication Infectious Disease Society of America (IDSA) uses a slightly higher bleach bath concentration for recurrent SSTIs: 1/4 cup 6% bleach per 13 gallons of water, roughly around 0.007% NaOCl Slightly higher concentrations could provide antimicrobial properties, though at risk of skin irritation
Ross, 2023 [200]	Review	1/4 cup per half-tub of water (children) or 1/2 cup per full bathtub of water (adults)	2–5 min	DBBs may be helpful in preventing AD flares Patients with “broken skin, weeping, crusting or sores” recommended to have DBBs Soak for 2–5 min and pat dry
Stolarczyk et al., 2023 [201]	Nonrandomized controlled trial	0.005%	5–10 min, twice weekly for 12 weeks	15 participants with AD compared with 5 participants without AD Baseline TEWL initially elevated in patients with AD compared with non-AD; there was also a strong correlation between baseline TEWL and EASI After 12 weeks of DBBs, 53.3% of patients with AD demonstrated significant reduction in AD severity; 87% reported better quality of sleep TEWL was significantly decreased in individuals with AD at both 6 weeks and 12 weeks; SC integrity improved as early as 6 weeks Microbial diversity and S. aureus abundance not significantly affected by DBBs
Amgarth-Duff et al., 2024 [202]	Systematic review	Refers to Wong et al.	Refers to Wong et al.	Reviewed the evidence of treatments for skin diseases in limited-resource environment
Brooks and Yosipovitch, 2024 [203]	Review	0.005%	Refers to Stolarczyk et al.	Guidelines recommend DBBs only for patients with moderate-to-severe AD; improvement may only be seen in 20% of patients NaOCl does not appear to affect skin barrier or contribute to antimicrobial resistance
Chu et al., 2024 [18]	American guidelines	Not specified	Not specified	Evidence-based guidelines for management of AD by American Academy of Allergy, Asthma and Immunology/American College of Allergy, Asthma and Immunology Joint Task Force DBBs are not recommended in mild AD based on minimal benefits for this subgroup
Deva et al., 2024 [204]	Systematic review	Not specified	Generally recommended 5–10 min, 2–3 times weekly (some guidelines specified, others omitted or did not recommend)	Systematic review of world guidelines for management of AD between 2005 and 2021 DBBs recommended by 50% of the guidelines; others did not recommend or did not mention them Low-certainty evidence that DBBs reduce S. aureus colonization or patient-reported improvement Frequency of DBBs variable or not specified
Kawasaki et al., 2024 [205]	Prospective, observational cohort study (abstract)	Not specified	Not specified	Skin microbiome and S. aureus genes may be able to predict responsiveness to DBB therapy in a patient with AD More unstable clinical disease could be less responsive to bleach
Pagliaro et al., 2024 [206]	Review	0.005%	Not specified	DBBs currently recommended by guidelines for moderate-to-severe AD only Antimicrobial effects of bleach are demonstrated at higher concentrations than currently recommended in AD; DBBs likely modulate inflammation and the skin barrier Potential adverse effects include asthma exacerbation, skin irritation, and skin dryness; most of these effects are transient
Shah et al., 2024 [207]	Case series	1 tsp per 15 L (using 5% bleach)	Wear pajamas for 10 min, twice weekly	Explored a new alternative to DBBs for patients with AD without access to bathtub: cotton long-sleeve pajama or Indian kurta-pajama soaked in bleach solution for 5 min 11 patients who tried this intervention reported satisfaction and no adverse effects
Zha and Usatine, 2024 [208]	Review	0.005% ≈ 1/2 cup per full bathtub (using 5% bleach)	5–10 min, twice weeklyc	DBBs may reduce inflammation and decrease S. aureus colonization and may be used for those who develop frequent infection

NaOCl sodium hypochlorite, AD atopic dermatitis, S. aureus Staphylococcus aureus, DBB dilute bleach bath, IGA Investigator Global Assessment, BSA body surface area, EASI Eczema Area and Severity Index, NF-κB nuclear factor-κB, TEWL transepidermal water loss, TCS topical corticosteroid, CDLQI Children Dermatology Life Quality ^aConcentration units and preparation instructions are presented as reported in the original studies. This approach was intentionally maintained to reflect inconsistencies in the literature

^bDilutions were performed with water

^cSpecifiers were included if it was mentioned in the cited text (e.g., “full” or “half-filled”)

^dPresented bleach instructions that came from a study not included in this review

Index, DLQI Dermatology Life Quality Index

S. aureus in AD Pathogenesis

DBBs emerged as a potential intervention to reduce S. aureus colonization, AD severity, and secondary SSTIs [136, 137, 140]. Eczematous skin is characterized by skin barrier disruption and alterations in the skin microbiome, contributing to increased susceptibility to S. aureus colonization and subsequent secondary skin infections [140–142, 148, 149, 155, 159, 161, 172, 174, 181]. S. aureus colonization can occur both on lesional and nonlesional AD skin and, less commonly, on the skin of individuals without AD [141, 160]. Several well-designed studies have demonstrated an association between colonization status and AD severity [143], as well as a positive correlation between relative S. aureus abundance and clinical disease severity [149, 160, 190]. S. aureus can also produce superantigens that induce the release of toxins, exacerbating inflammatory pathways and further compromising the skin barrier [137, 142, 161, 177, 181].

Bleach Bath Efficacy in AD

DBBs were initially met with a high degree of promise and optimism for their potential to improve AD outcomes. Although the first randomized controlled trial evaluating the efficacy of DBBs was carried out in combination with intranasal mupirocin spray (excluded in the current screening) and had a positive outcome, many argued that the bleach component was the primary driver of AD improvement [139, 148, 168]. Notably, clinical improvement was only observed in bleach-submerged body areas, while head and neck areas showed no significant difference [139, 148, 168]. Furthermore, in two open-label prospective studies and one randomized controlled trial, DBBs reduced AD severity and improved several measures, including Eczema Area and Severity Index (EASI), Investigator Global Assessment (IGA), body surface area (BSA), and itch evaluations [147, 149, 183].

However, increasing skepticism emerged in response to conflicting evidence. In a 2017 systematic review and meta-analysis of five studies, Chopra and colleagues evaluated the efficacy of bleach baths [164]. Four of these studies compared DBBs with controls, but two sets of three studies were pooled for each analysis: one comparing EASI and another comparing BSA. Remarkably, there was no significant clinical difference in AD severity in the pooled analysis, suggesting that water baths alone may be sufficient to improve AD severity.

This current scoping review includes four of the five studies addressed by Chopra et al. [147, 149, 160, 162]. Ryan et al. were not included in the pooled analysis as they used a wash formulation and lacked a water bath control group for comparison. Hon et al. concluded that water baths are equally or possibly even more effective than bleach baths for AD [162]. In contrast, Wong et al. reported a significant improvement in EASI, BSA, and itch scores with DBBs [149], and Gonzalez et al. observed no significant differences in both AD severity and total bacterial density (including S. aureus) between the two groups when allowing for background use of topical corticosteroids (TCS), suggesting that there was no additional clinical benefit of DBBs on top of topical therapy [160]. However, Majewski et al. revealed that bleach baths may reduce the frequency of TCS usage as early as 6 weeks [183], which can be a favorable outcome given the cutaneous and systemic risks associated with chronic TCS use [154, 189]. Moreover, based on limited evidence, there was no attributable risk reduction in systemic antibiotic use after employing DBB [176].

Although DBBs are generally well-tolerated, side effects of skin irritation, burning, stinging, and worsening of asthma may occur, especially at higher concentrations [137, 147, 149, 163, 177, 181, 182, 199, 206]. DBBs may increase skin pH, as shown in at least one study, which could theoretically worsen skin inflammation [157, 163], though in a small randomized controlled trial, Shi and colleagues showed that this change, along with changes in SC hydration and TEWL, were transient [163].

Shifting Understanding of Bleach’s Mechanistic Role in AD

The debate surrounding adjunctive bleach baths has unfolded alongside evolving insights into the mechanistic actions of bleach. In an in vitro study, Sawada et al. demonstrated that typical DBB concentrations were insufficient to exhibit antimicrobial properties [184], and other studies have also consistently demonstrated persistent colonization of S. aureus [149, 160, 178, 182].

In the mid-2010s, there was a notable shift in the content of the published literature, with more favorable recognition of the anti-inflammatory and antipruritic properties of DBBs for AD management [5, 8, 154, 155, 161, 166, 184, 194, 206, 208]. Mechanistic studies suggest that NaOCl in bleach baths suppresses key genes involved in the NF-κB pathway, a major driver of cutaneous inflammation [5, 8]. It also appears to impact inflammation and itch in AD through modulation of proinflammatory cytokines and pruritogens (e.g., IL-1, IL-6, TNF, IL-4, IL-13, thymic stromal lymphopoietin [TSLP], and IL-31), T cell activation, histamine release, and IgE production [5, 8]. Further supporting this purported mechanism, a recent in vitro study by Huang et al. showed that NaOCl pretreatment of keratinocytes reduced serine protease expression, which is associated with skin barrier function and itch [197]. However, strong evidence for NaOCl modulation of inflammation remains limited, and additional randomized controlled trials, particularly at higher concentrations, are needed [199].

Guidance and Formulations

Current US, Canadian, European, and Asian guidelines recommend 0.005% NaOCl maintenance baths for moderate-to-severe AD [18, 19, 196, 204, 206]. European guidelines also specifically comment on safety and tolerability in pregnancy [186]. Furthermore, the Italian Consensus Conference in 2015 noted the benefits of a 0.005% bath or wash for management of comorbid cutaneous bacterial infections [159]. However, adjunctive bleach baths are generally not recommended in mild AD, considering the minimal benefits in this subgroup and the small risk of adverse effects [18, 19]. A systematic review of world guidelines for AD management between 2005 and 2021 demonstrated an overall lack of consensus for DBBs worldwide [204]; only 50% of the guidelines recommended bleach baths, while others did not recommend or mention it for management.

An important limitation in consistent NaOCl recommendations is the lack of standardized methods to report recommended concentrations. Any reported concentrations, vehicles, exposure length, frequency, and duration in the literature are summarized in Table 3; this includes the reported recommendations or any study designs mentioned. While most clinical studies and guidelines have reported a goal concentration of 0.005% NaOCl, instructions do not employ a standardized protocol (Table 3). Multiple studies have suggested that 0.005% NaOCl can be equivalent to either 1/2 cup of household 6% bleach in a full standard tub (40 gallons) of water or 1/4 cup in a half-filled bathtub [139, 145, 154, 155, 160, 164, 208]. In addition, 23 publications did not specify a concentration [18, 143, 144, 153, 156, 165, 167–169, 175–179, 181, 186–189, 196, 198, 204, 205]. Many authors also did not specify any preparation methods, stock concentrations, bathtub size, or volume of the solution. Realizing the variability of household bathtubs, Collier et al. analyzed common bathtub models and developed a conversion chart to calculate bleach bath concentrations on the basis of a fixed distance from the tub base to the overflow valve [63].

The most commonly reported bath duration and frequency was 5- to 10-min soaks, two to three times weekly, for maintenance (Table 3). The reported duration of bathtub submersion ranged from as little as 2 min [200] to as long as 30 min [142]. Some studies also reported an initial intensive 5-day to 2-week course of daily bleach baths, followed by maintenance frequencies [158, 161, 167]. However, similar to the concentration recommendations, treatment exposure times, frequencies, and durations were often omitted and varied significantly. Starting in 2013, new delivery methods for bleach therapy were presented, including washes, sprays, topical solutions, and soaked clothing. Washes formulated with 0.006% NaOCl have offered a convenient alternative for individuals who did not have access to a bathtub or found the bathing process too cumbersome [147, 151, 182]. Majewski et al. noted that 61% of patients preferred the wash over the bath [182]. Additional at-home methods included soaking pajamas in traditional bleach bath solutions or pouring a prepared solution into a spray bottle [154, 166, 185, 207].

Noneczematous Skin Conditions

Recently, there has been growing interest in the use of NaOCl in noneczematous skin conditions, as supported by both anecdotal and emerging clinical evidence. Between 2004 and 2022, 23 studies demonstrated NaOCl’s efficacy in various dermatoses (Table 4) [15, 209–230].

Table 4.

Summary of studies investigating sodium hypochlorite (NaOCl) and noneczematous skin conditions^a

Study, year	Study type	Disease target	Concentration of NaOCl	Key points
Piraccini et al., 2004 [209]	Review	Onycholysis	Not specified	Onycholysis caused by Pseudomonas can be treated with NaOCl solution
Ashine et al., 2009 [210]	Case series (abstract)	Podoconiosis	Not specified	Followed 30 patients with podoconiosis in Ethiopia Treatment regimen with soap, water, dilute bleach, emollient, and bandages increased all patient’s mean Dermatology Life Quality Index Score (DLQI) NaOCl treatment is only USD $4 per patient per month
Leung et al., 2013 [15]	Original research	Radiation dermatitis	0.005%	NaOCl improves acute radiation dermatitis in mice by inhibiting nuclear factor κB (NF-κB)-dependent genes and preventing skin ulceration NaOCl reversed features of skin aging in mice, enhancing epidermal thickness and proliferation
Stanford University, 2015 [211]	Randomized controlled trial, phase III	Radiation dermatitis	0.005–0.010%	In patients with head and neck cancer, Dakin’s solution was applied topically to the arm up to 3 h in advance of each radiation treatment No significant difference when compared with saline control
Patel et al., 2015 [212]	Case report (abstract)	Harlequin ichthyosis	Not specified	A 35-week-old female patient in the neonatal intensive care unit was treated supportively with frequent dilute bleach baths, intravenous (IV) fluids, and emollient use, resulting in spontaneous shedding of keratotic crusting on skin within 1 month She eventually progressed to a phenotype resembling congenital ichthyosiform erythroderma
Brooks et al., 2016 [213]	Randomized controlled trial	Podoconiosis	0.0125%	Current treatment regimen involves a 30-min soak of feet and legs in a bleach bath, followed by air-drying and petroleum jelly as treatment for podoconiosis
Michaud et al., 2016 [214]	In vivo	Ulcerative dermatitis	0.005%	Compared 3 topical agents (triple antibiotic, 10% povidone-iodine + 1% silver sulfadiazine, and 0.005% NaOCl) for treatment of ulcerative dermatitis in mice models Healing demonstrated in 71% treated with 0.005% NaOCl compared with 34% treated with triple antibiotic, and 34% treated with 10% povidone-iodine ointment + 1% silver sulfadiazine cream NaOCl was significantly associated with successful skin healing
Oreta et al., 2016 [215]	Case report (abstract)	Epidermolytic hyperkeratosis	Not specified	Patient with epidermolytic hyperkeratosis and secondary scabies infestation was treated with bleach baths, keratolytics (tazarotene, urea, emollients), and permethrin with great success
Singer et al., 2016 [216]	Observational study (abstract)	Epidermolysis bullosa	Not specified	9/14 patients reported using bleach in their baths
Horst, 2017 [217]	Uncontrolled trial	Radiation dermatitis	Not specified	For 6 weeks, participants with breast cancer topically applied Dakin’s solution daily for 10 min within 60 min of radiation therapy Of the 14 women with data available, 6 developed grade 3 or 4 radiation dermatitis (as defined by the Stanford Radiation Dermatitis Scoring System)
Levin et al., 2017 [218]	Observational study (abstract)	Epidermolysis bullosa (EB)	Not specified	Of 73 patients with EB, bathing was the most frequently reported type of cleansing method, with some patients indicating addition of dilute bleach
Levin et al., 2018 [219]	Observational study (abstract)	EB	Not specified	Analysis of 255 surveys of patients with EB indicated that 57% of patients who used an additive while bathing used bleach
Singer et al., 2018 [220]	Observational study	EB	1/4 cup per 20-gallon bathtub	Determined that Staphylococcus aureus and Pseudomonas aeruginosa were common colonizers of patients with EB Less than half of patients used bleach in their bathing routine with varied reports in bleach concentration and usage
Wat et al., 2018 [221]	Case report	Omenn syndrome	0.005%	A female infant with Omenn syndrome treated 3 times weekly with 0.005% NaOCl full-body compresses, rinsing with sterile water and emollient Improvement of thick, yellow scales noted within 5 days
Richburg and Blachshear, 2019 [222]	In vivo (abstract)	Ulcerative dermatitis	0.005% (spray)	8 mice with ulcerative dermatitis were treated 4 times a week over 2 weeks with various topical agents 10% chlorhexidine solution demonstrated greater reduction in erythema compared with NaOCl; however, NaOCl was more effective compared with standard triple antibiotic ointment and ophthalmic triple antibiotic ointment
Kumari, 2020 [223]	Review (abstract)	EB	Not specified	DBBs were used in the treatment regimen of EB
Shayegan et al., 2020 [224]	Observational study	Epidermolysis bullosa	0.002–0.09%	Results from a survey with 203 patients with EB from 13 centers Out of the 131 patients who used a bath additive, 71 used DBBs; 19 patients used bleach only
Butala et al., 2021 [225]	Case report	Ichthyosis prematurity syndrome (IPS)	Not specified	A patient diagnosed with IPS was treated with bleach compresses 3 times weekly, resulting in significant cutaneous improvement
Dorostkar et al., 2021 [226]	Randomized controlled trial	Acne	0.005%	Within 1 month, the total number of papules and pustules decreased from 759 to 476 (p < 0.0001) The number of papules decreased after 1 month (p < 0.0001), while the number of pustules did not change significantly (p = 0.692)
Fernandez et al., 2022 [227]	Survey	Hidradenitis suppurativa (HS)	Not specified	A Facebook survey was completed by 438 patients with HS; 93.8% were female participants Reported treatment effectiveness rating for bleach baths was only 1.52 ± 0.80 on a scale of 1–5
Ajayi and Sokumbi, 2022 [228]	Review	HS	Not specified	Reported NaOCl as an effective adjunct treatment for HS
Alheggi et al., 2022 [229]	Observational study	Epidermolysis bullosa	0.005%	Survey collected from 37 patients with EB 22 participants used a bath additive; 9 individuals used bleach, and of them, exclusively used bleach
Poondru et al., 2023 [230]	Observational study	HS	Not specified	Results from questionnaire regarding HS wound management and patient perspectives 75/302 individuals used bleach; slightly less than 50 participants rated poor or average perceived treatment efficacy

NaOCI sodium hypochlorite, DLQI Dermatology Life Quality Index Score, NF-κB nuclear factor κB, EB epidermolysis bullosa, IPS ichthyosis prematurity syndrome, HS hidradenitis suppurativa

^aConcentration units and preparation instructions are presented as reported in the original studies. This approach was intentionally maintained to reflect inconsistencies in the literature

The earliest reports were limited to specific-use scenarios without sufficient efficacy data. For example, in 2004, a review paper briefly noted using NaOCl to treat onycholysis caused by Pseudomonas [209]. A pivotal 2013 study examined potential mechanisms and clinical applications of bleach treatments for radiation-induced dermatitis in murine and human models [15]. Leung and colleagues (2013) demonstrated that topical NaOCl inhibits NF-κB signaling, offering insight into potential therapies for inflammation and aging [15]. Mechanistically, they found that in keratinocytes, NaOCl reversibly suppressed NF-κB-dependent gene expression by oxidizing critical cysteine residues on IKK (inhibitor of NF-κB kinase), thereby blocking NF-κB activation [15]. In mouse models, topical NaOCl reduced skin inflammation and mitigated NF-κB-mediated epidermal pathology [15]. Furthermore, in models of radiation dermatitis and age-related skin changes, treatment with NaOCl decreased disease severity, downregulated proinflammatory gene expression, and enhanced epidermal thickness and cellular proliferation [15].

Following these novel insights, additional in vivo murine studies highlighted significant skin improvements using a low-concentration 0.005% NaOCl topical agent for ulcerative dermatitis [214, 222]. The dilute NaOCl agent was associated with superior skin healing [214] and reduced erythema [222] when compared with other topical agents, including triple antibiotic, 10% chlorhexidine, or 10% povidone-iodine mix with 1% silver sulfadiazine.

Two randomized controlled trials have also evaluated the clinical efficacy of NaOCl in radiation dermatitis, though results were mixed [211, 217]. A 2015 study found no significant difference in radiation dermatitis severity with patients treated with topical NaOCl (0.005–0.010%) versus controls [211], though a later 2017 single-arm study reported more favorable outcomes: Only 6 out of 14 patients with breast cancer developed grade 3 or 4 radiation dermatitis after receiving daily topical Dakin’s solution (0.0125% NaOCl) for 10 min within 60 min of radiation therapy [217].

Seven studies examined a role for NaOCl in the treatment of epidermolysis bullosa (EB), a condition characterized by extreme skin fragility and frequent secondary infections [216, 218–220, 223–225]. Most of these reports were based on observational surveys that revealed DBB as a commonly adopted adjunctive cleansing practice. Though concentrations and frequency varied, the rationale to reduce S. aureus and P. aeruginosa colonization was consistent [220]. These bacterial strains are often implicated in delayed wound healing and increased morbidity among patients with EB. However, NaOCl utilization remains inconsistent across cohorts, and standardized protocols are lacking.

Rare and severe congenital disorders, including harlequin ichthyosis, ichthyosis prematurity syndrome (IPS), and epidermolytic hyperkeratosis, have shown anecdotal responses to NaOCl as a part of the treatment regimen. Case reports have described improvements in desquamation, bacterial burden, and skin barrier function following bleach baths or compresses [212, 215, 225]. Bleach-based treatments have been explored in other inflammatory conditions. In a randomized controlled trial in patients with acne vulgaris, a significant reduction in papule count following use of 0.005% NaOCl was observed [226]. Similarly, in hidradenitis suppurativa, a review [228] and patient survey data [227] suggest a potential role for NaOCl as an adjunctive anti-inflammatory and antimicrobial agent, though patient-reported efficacy data remain in early stages [230].

Discussion

This scoping review provides a comprehensive overview of the past, present, and emerging applications of dilute NaOCl in clinical dermatology (Fig. 4). Over the past century, our understanding of the mechanism of and potential cutaneous uses for NaOCl has grown multifold (Fig. 3). Since its earliest uses as an antiseptic agent, multiple studies have sought to find an optimal concentration and formulation—one that harnesses its antimicrobial, anti-inflammatory, and wound-healing properties, while also minimizing potential consequences of cytotoxicity and skin irritation [7, 9, 15, 22, 28–30, 33, 34, 37, 55, 83, 85, 89, 90, 98, 110, 123].

Fig. 4.

Summary of past, present, and future of sodium hypochlorite in dermatology

Many studies have highlighted the dose-dependent and exposure-time-dependent nature of these solutions [6, 7, 22, 44, 49, 53–55, 61, 71, 77, 101, 104, 114, 119, 121]. However, the relative NaOCl concentration in bleach—and thus efficacy—is also influenced by the preparation methods, storage methods, and the freshness of the solution [5, 6, 8, 10, 24, 39, 48, 49, 54, 55]. These studies should provide a guide for further exploration into optimal formulation.

In addition, the properties of NaOCl are further altered in the setting of natural animal tissue, necrotic material, and other organic matter [23, 39, 48, 49, 54, 81, 86]. This is important when comparing in vitro, in vivo, and human clinical study analyses. These variables may also explain some of the discrepancies in literature regarding the minimum effective concentrations and toxicity thresholds. Precise, standardized protocols are needed to better inform therapeutic effectiveness and safety.

More recently, the broad antimicrobial and antibiofilm effects of NaOCl have been explored as treatment for the bacterial burden of chronic wounds, especially amid the challenge of rising MDROs. Multiple clinical reports have suggested an adjunctive NaOCl solution to improve recalcitrant wounds not responding to antibiotics [107, 108, 124]. Moreover, NaOCl may serve a broader function in supporting the major phases of wound healing after hemostasis: inflammation, proliferation, and maturation [89, 107]. Clinical reports have highlighted NaOCl’s supportive role in granulation tissue formation [107, 116], and there are also additional model systems that show a role in modulating angiogenesis, MMPs, and collagen deposition [91, 93, 98, 106, 111, 117, 130]. These observations underscore a need for large-scale, randomized controlled studies to assess wound healing.

In the 21st century, the well-established antimicrobial effects of NaOCl inspired investigations specifically aimed at S. aureus colonization, a key factor important in AD pathogenesis and severity, as well as SSTIs. This was evident in the apparent spike in publications in the 2010–2019 decade (Fig. 3). Studies have evolved in parallel to support mechanistic insights into both AD pathogenesis and the biologic properties of NaOCl. For AD studies, researchers most commonly used a more dilute concentration of bleach, 0.005% NaOCl, which interestingly failed to consistently demonstrate significant antimicrobial effects, but was also associated with notable improvement in clinical disease [138, 149, 154, 184, 204]. On the basis of these findings, there has been a noteworthy shift in publications focusing on the anti-inflammatory and skin-barrier-modulating properties of NaOCl [15, 96, 105, 122, 157, 163, 197, 201, 203]. NaOCl may have applications in common dermatoses far beyond AD; laboratory, observational, and clinical studies have shown efficacy in acne vulgaris, hidradenitis suppurativa (HS), radiation dermatitis, ulcerative dermatoses, multiple genodermatoses, and even skin aging [225–228, 230].

Strengths of this scoping review and synthesis include its broad temporal scope, encompassing literature from the early 1900s to the present, and its inclusion of a wide variety of study designs. To date, no prior review has offered a comprehensive overview of historical trends in the context of dermatological care, particularly concerning evolving clinical attitudes, dosage recommendations, and application protocols. Careful curation of this content provides valuable insights for current and future directions in therapeutic formulation and clinical practice.

Limitations of this review include using a rigorous search strategy, which eliminated several studies that used NaOCl in combination with other ingredients and without an appropriate comparator group. This limits generalizability to broader clinical scenarios where adjunctive use of multiple agents is common and synergistic roles may exist. The decision to focus on bleach and its active ingredient of NaOCl, rather than HOCl, was guided by the large body of literature, historical significance and use, and typical recommendation in routine clinical practice. Future studies focused on HOCl may offer complementary insights into the mechanistic and clinical applications of bleach baths.

To our knowledge, only a limited number of clinical trials are currently exploring dermatological uses of dilute NaOCl [231, 232]. Notably, one of the trials used a patented 0.006% NaOCl wash, CLn (TopMD Skin Care; Dallas, Texas, USA), that has been marketed since 2014 [231, 233]. This same wash was used in two studies included in this review [147, 182]. During our screening process, we also noted at least eight trials that were either withdrawn or terminated owing to inadequate enrollment. In addition, several completed trials had not posted results. These challenges, combined with the potentially limited commercial value of using an inexpensive, widely accessible compound such as NaOCl, may explain the relatively modest investment in clinical trials. In the age of targeted advanced therapies, it is also reasonable to infer that both investigators and patients may underestimate or overlook the utility of basic interventions with NaOCl. Substantial heterogeneity in bleach preparation, concentration, formulation, and instructions also makes direct comparison among studies challenging. Standardized guidelines and large-scale randomized and controlled clinical trials are warranted to fully elucidate and optimize NaOCl’s promising role in dermatology.

Conclusions

Sodium hypochlorite has evolved from an antiseptic chemical used solely in wound care to a primary and adjunctive treatment modality that has promise for the treatment of a diversity of infectious and noninfectious inflammatory dermatological conditions. Therapeutic efficacy depends on multiple parameters, including dose, exposure, pH, and intended application site. Randomized controlled clinical trials and standardized preparation and formulation are imperative in future research to explore the full potential of NaOCl in modern dermatology.

Supplementary Information

Below is the link to the electronic supplementary material.

Funding

No funding was received for this study.

Declarations

Conflicts of interest

Raj Chovatiya is an editorial board member of American Journal of Clinical Dermatology. Raj Chovatiya was not involved in the selection of peer reviewers for the manuscript nor any of the subsequent editorial decisions. Raj Chovatiya has served as an advisor, consultant, speaker, and/or investigator for AbbVie, Acelyrin, Alumis, Amgen, AnaptysBio, Apogee Therapeutics, Arcutis Biotherapeutics Inc., Argenx, Astria Therapeutics Inc., Avalere Health, Beiersdorf, Boehringer Ingelheim, Bristol Myers Squibb, Cara Therapeutics, Castle Biosciences, Celldex CLn Skin Care, Dermavant, Eli Lilly and Company, EMD Serono, Formation Bio, Galderma, Genentech, GSK, Incyte, Johnson & Johnson, Kenvue, LEO Pharma, L’Oréal, Nektar Therapeutics, Novartis, Opsidio, Pfizer Inc., RAPT, Regeneron, Sanofi, Sitryx, Takeda, TRex Bio, UCB, and Zai Lab. Tiago Torres is an editorial board member of American Journal of Clinical Dermatology. Tiago Torres was not involved in the selection of peer reviewers for the manuscript nor any of the subsequent editorial decisions. Tiago Torres has received consultancy and/or speaker’s honoraria from and/or participated in clinical trials sponsored by AbbVie, Almirall, Amgen, Arena Pharmaceuticals, Biocad, Biogen, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Fresenius Kabi, Janssen, LEO Pharma, Eli Lilly, MSD, Mylan, Novartis, Pfizer, Samsung-Bioepis, Sanofi-Genzyme, Sandoz, and UCB. Christy H. Chang, Maura Devine, Deborah Woo, and Theresa Hopkins have no conflicts of interest to declare.

Ethics approval

This study did not require ethics approval as it did not involve human participants, animal subjects, or identifiable personal data.

Consent to participate

Not applicable.

Consent for publication

Not applicable.

Availability of data and material

The data supporting the findings of this study are available within the published literature cited in the manuscript.

Code availability

Not applicable.

Authors’ contributions

CHC—concept and design; data curation; data interpretation and analysis; drafting of manuscript. MD—data curation; data interpretation and analysis; drafting of manuscript. DW—data curation; data interpretation and analysis; drafting of manuscript. TH—data curation; data interpretation and analysis. TT—critical revision for important intellectual content. RC—concept and design; data interpretation and analysis; drafting of manuscript; supervision