Prebiotics, Probiotics, and Postbiotics for Acne Vulgaris: A Systematic Review

Abstract

Introduction

Microbiome-modulating therapies including prebiotics, probiotics, and postbiotics have been increasingly investigated as adjuncts or alternatives for managing acne vulgaris through effects on the gut–skin axis, inflammation, and barrier function. The objective of this systematic review is to characterize the safety and efficacy of oral and topical prebiotics, probiotics, and postbiotics in managing acne vulgaris.

Methods

We conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review of randomized controlled trials, cohort studies, and case–control studies evaluating oral and topical prebiotics, probiotics, and postbiotics for acne vulgaris from inception to August 2025 in PubMed, Embase, Web of Science, and Cochrane. Inclusion criteria comprised clinical studies reporting on safety and/or efficacy of topical and/or oral prebiotic, probiotic, and postbiotic therapy in patients with acne vulgaris.

Results

In total, 33 studies evaluating 2112 total patients were included, with treatment durations of 4–25 weeks; 5 prebiotic, 24 probiotic, and 7 postbiotic studies were included, with 2 studies comparing prebiotics and probiotics and 1 study comparing prebiotics and postbiotics against each other. Safety was favorable across all modalities with no serious adverse events reported. Pooled mean total lesion reductions were −37.2% for prebiotics, −45.2% for probiotics, and −49.5% for postbiotics, versus −37% for controls.

Conclusions

Prebiotic, probiotic, and postbiotic therapies appear to be safe and associated with clinically meaningful lesion reductions in acne. They may increase tolerability and add additional efficacy to standard acne treatments including topical and oral antibiotics and retinoids. Probiotics currently have the strongest evidence base, while prebiotics and postbiotics are promising adjuncts. Larger, standardized randomized trials are needed to clarify comparative efficacy, optimal formulations, and durability.

Key Summary Points

The gut–skin axis and human microbiome likely play a role in the pathogenesis of acne vulgaris.

Prebiotics are nondigestible food ingredients that selectively stimulate beneficial microorganisms in the gut. Probiotics are live microorganisms that, when administered in the appropriate amounts, have a positive effect on host health. Postbiotics are inactivated microbial elements that exert biological effects without requiring viability.

This systematic review aimed to characterize the safety and efficacy of oral and topical prebiotics, probiotics, and postbiotics in managing acne.

This review contained 33 studies that reported data on 2112 patients for whom oral or topical prebiotics, probiotics, and/or postbiotics were used for treatment of acne vulgaris.

Prebiotics, probiotics, and postbiotics modulate the gut–skin axis and microbiome, and therefore may be advantageous in managing acne vulgaris as a complementary approach to traditional therapies.

Introduction

Acne vulgaris is a common dermatologic disorder characterized by recurrent comedones, pustules, papules, or nodules on the face, neck, or trunk [1]. It is most common among adolescents and young adults, with prevalence estimated around 85% in this demographic [2], though it may persist into adulthood. More than 50 million Americans have acne [3]. Acne has a significant impact on quality of life [4], and the burden of acne is ranked second among all skin diseases, behind dermatitis [5].

The pathogenesis of acne is multifactorial, arising from the interplay of increased sebum production, abnormal follicular keratinization, colonization with Cutibacterium acnes (formerly Propionibacterium acnes), and inflammation with contributions from genetic, hormonal, and environmental factors [6]. Management of acne include topical agents, systemic antibiotics, hormonal therapies, oral isotretinoin, physical modalities, complementary and alternative approaches, and dietary or environmental modifications. [7]

The gut–skin axis and human microbiome have been increasingly investigated, generating interest in the potential of microbiome-modulatory agents as treatments for various diseases, including acne vulgaris. The microbiome comprises bacteria, fungi, viruses, and their metabolites, as well as their dynamic interactions with the surrounding environment [8]. The most dominant bacterial phyla on the skin are Actinobacteria, Proteobacteria, Bacteroidetes, and Firmicutes [9]. In areas of oily skin, such as the face, back, and scalp, the lipophilic species of Cutibacterium predominates [9]. Cutibacterium acnes (C. acnes) is the current name for the species previously known as Propionibacterium acnes; the name was changed following a taxonomic reclassification in 2016 [10]. In the pilosebaceous unit of oily areas, 90% of microbiota is represented by C. acnes [9]. Staphylococcus epidermidis and the Malassezia species have also been documented in acne [9]. Limited studies of gut microbiota in patients with acne have identified overall reduced diversity, a higher Bacteroidetes:Firmicutes ratio, enrichment of Proteobacteria, depletion of Actinobacteria, and loss of beneficial genera, including Lactobacillus and Bifidobacterium [11–13].

Given this relationship, prebiotics, probiotics, and postbiotics have been investigated as potential therapeutics for managing acne vulgaris. Prebiotics are nondigestible food ingredients that selectively stimulate beneficial microorganisms in the gut [14]. In contrast, probiotics are live microorganisms that, when administered in the appropriate amounts, have a positive effect on host health per the 2002 World Health Organization (WHO) definition [15]. Postbiotics are inactivated microbial cells, components, or metabolites that exert biological effects without requiring viability [15].

The objective of this systematic review is to characterize the safety and efficacy of oral and topical prebiotics, probiotics, and postbiotics in managing acne vulgaris to equip the dermatologist with ample knowledge about the potential role they may play in managing acne.

Methods

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.

Study Eligibility

Studies were included if they involved patients diagnosed with acne vulgaris and treated with topical and/or oral prebiotics, probiotics, or postbiotics. Eligible study designs comprised randomized controlled trials, cohort studies, and case–control studies published between inception and August 2025. Case reports, case series, reviews, editorials, and nonhuman studies were excluded. Patients using topical or oral prebiotics, probiotics, or postbiotics for reasons other than acne were also excluded.

Search Strategy and Study Selection

A comprehensive search was conducted across PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL). The search strategy incorporated keywords such as “acne vulgaris”, “prebiotic”, “probiotic”, and “postbiotic” among others, connected by Boolean operators (AND, OR). Searches were conducted through August 2025, with the initial database search yielding 2435 records (Fig. 1). After removal of duplicate records (n = 491) and title/abstract screening by three independent reviewers (P.V.W., S.M.B., L.M.F.), 65 studies were selected for full-text review. Following full-text assessment, 33 studies met the inclusion criteria and were included in the systematic review (Fig. 1). All screening stages were conducted independently by reviewers, with discrepancies resolved through discussion.

Fig. 1.

PRISMA flow chart for systematic review on prebiotics, probiotics, and postbiotics for acne vulgaris

Data Extraction

Three reviewers (P.V.W., S.M.B., L.M.F.) independently extracted data from the included studies using a standardized data collection form. Extracted information included study characteristics (author, year, country, design), participant demographics (sample size, sex distribution, mean age, acne severity), treatment modality, treatment safety, and treatment efficacy (change in number of inflammatory acne lesions, number of noninflammatory acne lesions, total number of acne lesions, investigator global scale (IGA), and global acne grading system (GAGS)).

Risk of Bias Assessment

Risk of bias was assessed using the Cochrane Risk of Bias tool (RoB 1.0). The following domains were evaluated: sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessors, incomplete outcome data, selective outcome reporting, and other sources of bias. Each domain was rated as low, high, or unclear risk of bias. Assessments were performed by a single reviewer.

Data Synthesis and Statistical Analysis

Data on percent reduction in total, inflammatory, and noninflammatory acne lesion counts were extracted from each study arm and classified by intervention type (prebiotic, probiotic, postbiotic, or control). Where multiple eligible intervention arms were reported within a trial, each trial was included if it met the predefined criteria; comparator arms were pooled as controls. All analyses were conducted in R version 2024.12.1 + 563 using RStudio integrated development environment. Independent one-sample t-tests were applied to determine whether the mean percent lesion reduction within each intervention category differed significantly from zero. To evaluate whether interventions conferred benefit beyond controls, two-sample t-tests compared each intervention type directly with pooled control arms. Between-group differences were examined using one-way analysis of variance (ANOVA), with Tukey’s honestly significant difference (HSD) post hoc test for multiple pairwise comparisons. To assess whether route of administration influenced outcomes, a two-way ANOVA including intervention type, route (oral versus topical), and their interaction was conducted, with Tukey post hoc testing for pairwise contrasts. All tests were two-sided with significance threshold of α = 0.05. Results are presented as mean reductions with corresponding 95% confidence intervals, t-values, F-values, and adjusted p-values.

Results

A total of 33 studies met inclusion criteria, with a total number of 2112 participants (Table 1). Mean participant age ranged from 18 to 33 years, with the weighted average being 25.1 years. Treatment durations ranged from 4 to 25 weeks. Study designs comprised of randomized controlled trials, cohort studies, and split-face designs conducted across 14 countries. Most participants were adolescents or adults with mild-to-moderate acne vulgaris. Oral interventions predominated in prebiotic and probiotic categories, while topical formulations were more frequent for postbiotics. Few studies tested between-group outcomes (n = 3).

Table 1.

Summary of studies on prebiotics, probiotics, and postbiotics in managing acne vulgaris

Author, year	Intervention category	Intervention	Percent reduction in total lesion count	Percent reduction in inflammatory lesions	Percent reduction in noninflammatory lesions	Reduction in GAGS score	Reduction in GEA score	Reduction in IGA score
Rybak 2023 [21]	Probiotic	Bacillus indicus HU36, Bacillus subtilis HU58, Bacillus coagulans, Bacillus licheniformis, Bacillus clausii	−37%	−30%	−45%	NR	NR	NR
Zakharov 2023 [43]	Postbiotic	Acnevac (inactivated Cutibacterium acnes and Staphylococcus aureus antigens)	−67%	NR	NR	NR	NR	NR
Manfredini 2023 [22]	Probiotic	Lactobacillus reuteri, Lactobacillus casei subsp. rhamnosus, Lactobacillus plantarum, 109 CFU plus topical azelaic acid and hydroxypinacolone retinoate	−37%	NR	−43%	NR	NR	−6%
Kwon 2014 [16]	Prebiotic	Lactobacillus-fermented Chamaecyparis obtusa	−53%	−71%	−56%	NR	NR	NR
Kim 2010 [23]	Probiotic	Lactoferrin mixed in fermented milk containing probiotics (Lactobacillus bulgaricus and Streptococcus thermophilus)	−37%	NR	−37%	NR	NR	NR
Kim 2010 [23]	Probiotic	Fermented milk (Lactobacillus and Streptococcus cultures)	−17%	NR	−17%	NR	NR	NR
Kazandjieva 2022 [17]	Prebiotic	Hydroxypinacolone/retinyl palmitate, Iris florentia root extract, and a complex of three oligopeptides (copper tripeptide, dipepetide diaminobutyroyl, and acetyl tetrapeptide)	−28%	29%	−28%	−0.011	NR	NR
Kazandjieva 2022 [17]	Prebiotic	Hydroxypinacolone retinyl palmitate, Iris florentina root extract, and a complex of three oligopeptides (copper tripeptide, dipeptide diaminobutyroyl, and acetyl tetrapeptide) plus oral fructooligosaccharides and galactooligosaccharides with zinc, lactoferrin, and niacinamide	−31%	−26%	−34%	−0.015	NR	NR
Karoglan 2019 [24]	Probiotic	Cutibacterium acnes single-locus sequence typing type C3 and K8 (50% each)	−35%	−20%	−40%	NR	NR	NR
Karoglan 2019 [24]	ProbioticPro	Cutibacterium acnes single-locus sequence typing type C3 (55%), K8 (5%), A5 (30%), and F4 (10%)	−28%	−6%	−35%	NR	NR	NR
Kang 2009 [25]	Probiotic	Enterococcus faecalis CBT SL-5 extract	−38%	−45%	−30%	NR	NR	NR
Jung 2013 [26]	ProbioticPro	Unspecified	−66%	−67%	−70%	NR	NR	NR
Jung 2013 [26]	Probiotic	Minocycline + unspecified probiotic	−73%	−58%	−70%	NR	NR	NR
Irshad 2023 [27]	Probiotic	Hi-Flora	−84%	NR	NR	NR	NR	NR
Irshad 2023 [27]	Probiotic	Hi-Flora + azithromycin	−90%	NR	NR	NR	NR	NR
Ho 2022 [28]	Probiotic	Triamcinolone acetonide and collagen	NR	−7%	−4%	NR	NR	NR
Cui 2022 [44]	Postbiotic	8% Lactiplantibacillus plantarum VHProbi R E15 fermented lysate	−59%	NR	NR	−1	NR	NR
Cui 2022 [44]	Postbiotic	Lactiplantibacillus plantarum	−40%	−40%	−32%	NR	NR	NR
Anwar 2025 [29]	Probiotic	5% Lactococcus ferment lysate	−47%	NR	NR	NR	NR	NR
Biazzo 2025 [42]	Postbiotic	Lactiplantibacillus plantarum	−70%	NR	NR	NR	NR	NR
Eguren 2024 [30]	Probiotic	Lactobacillus rhamnosus CECT 30031 and Arthrospira platensis BEA_IDA_0074B	−28%	−16%	−18%	p = 0.02	NR	p = 0.03
Bae 2023 [45]	Postbiotic	HT-LM1013 (Lactiplantibacillus plantarum HY7714 and Lactobacillus rhamnosus HN001)	−32%	NR	−27%	NR	NR	NR
Alqam 2025 [31]	Probiotic	XYCM42 regimen (oral synbiotic–antioxidant supplement containing probiotic strains, zinc, B-vitamins, and plant polyphenols)	NR	−70%	−100%	NR	NR	2
Atefi 2025 [32]	Probiotic	Doxycycline and probiotic	−95%	NR	NR	p = 0.01	NR	p = 0.001
Sathikulpakdee 2022 [33]	Probiotic	Lactobacillus paracasei MSMC 39–1	−35%	−6.6	0%	NR	NR	NR
Rinaldi 2022 [34]	Probiotic	B. breve BR03 DSM 16604, L. casei LC03 DSM 27537, L. salivarius LS03 DSM 22776	NR	NR	NR	−38.9	NR	NR
Alessandrini 2023 [35]	Probiotic	1% Bacillus subtilis bacteriocins	−58%	−59%	−58%	−56%	NR	NR
Min 2025 [18]	Prebiotic	Myoinositol-based herbal supplement	NR	−61%	−62%	NR	NR	NR
Min 2025 [18]	Probiotic	Bifidobacterium breve BR03 DSM 16604, Lactobacillus casei LC03 DSM 27537, and Lactobacillus salivarius LS03 DSM 22776	NR	−58%	−49%	NR	NR	NR
Han 2022 [36]	Probiotic	Enterococcus faecalis CBT SL-5 extract	NR	NR	NR	NR	NR	−20%
Rocha 2021 [37]	Probiotic	Phenylbutyric acid and ethyl pyruvate	NR	−84%	−94%	NR	NR	−77%
Marasca 2022 [39]	Probiotic	Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus	−37%	NR	NR	NR	NR	NR
Maloh 2025 [19]	Prebiotic	Herbal/myo-inositol based supplement	NR	−61%	−62%	NR	NR	NR
Majeed 2020 [46]	Postbiotic	LactoSporin® 2% cream	NR	−62%	−50%	NR	NR	NR
Lu 2016 [20]	Prebiotic	Oral green tea extract	−2.60%	NR	NR	NR	NR	NR
Liang 2023 [38]	Probiotic	Oral isotretinoin and oral Lactobacillus plantarum MH-301	NR	−72%	−71%	NR	NR	NR
Liang 2023 [38]	Probiotic	Oral Lactobacillus plantarum MH-301	NR	−51%	−52%	NR	NR	NR
Lebeer 2022 [40]	Probiotic	Lactobacilli cream	NR	−49%	−35%	NR	NR	NR
Kwon 2014 [16]	Postbiotic	Lactobacillus-fermented Chamaecyparis obtusa extract	NR	−65%	−53%	NR	NR	−1.8
Kim 2021 [41]	Probiotic	CJLP55 (Lactobacillus plantarum)	54%	−68%	NR	NR	NR	−44%

Safety profiles were favorable across all studies with no serious adverse events. Across all modalities, lesion reductions were consistent and clinically meaningful. Pooled mean total lesion reductions were −37.2% for prebiotics, −45.2% for probiotics, and −49.5% for postbiotics, compared with −37.0% for controls. Lesion reduction was seen in control groups because most studies assessed the additive benefit of biotic therapy in conjunction with standard treatments. Within-group improvements reached statistical significance for each biotic type (prebiotics p = 0.041; probiotics p < 0.0001; postbiotics p = 0.0089), whereas between-group comparisons and route-of-administration effects were nonsignificant.

Prebiotics

In total, five studies investigated prebiotic formulations, four oral and one topical [16–20]. Prebiotics included fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), inositol derivatives, and botanical extracts. Oral prebiotics achieved mean total lesions reductions of −31% (95% CI −0.705 to −0.039), inflammatory lesion reductions of −49.3%, and noninflammatory lesion reductions of −52.7%. Topical prebiotics yielded −40.3% reduction in total lesions, −21% in inflammatory lesions, and 42% in noninflammatory lesions.

Probiotics

A total of 24 studies examined probiotics, 13 oral and 11 topical [18, 21–42]. Probiotics primarily included Lactobacillus and Bifidobacterium species, with some multistrain formulations incorporating Bacillus coagulans or Bacillus clausii. The pooled mean total lesion reduction was −45.2% (95% CI −0.612 to −0.292), inflammatory lesion reduction averaged around −88.3%, and noninflammatory lesion reduction −47.9%.

Postbiotics

A total of seven studies examined postbiotics, one oral and six topical [16, 42–46]. Postbiotics included heat-treated or lysed bacterial preparations and bacterial metabolite creams. Oral postbiotics achieved mean total lesion reductions of −52% to −58% (mean −49.5%, 95% CI −0.754 to −0.236), while topical postbiotics demonstrated −46% to −55% improvement in inflammatory lesions and −40% in noninflammatory lesions.

Risk of Bias

Most studies demonstrated acceptable methodological rigor but exhibited variability across domains (Fig. 2). Randomization and data completeness were generally well maintained, while blinding and allocation concealment were less consistent, reflecting the practical and methodological challenges of nutraceutical trial designs. Several studies had unclear risk in selective reporting and performance bias, though outcome data were typically transparent and comprehensive. Overall, while methodological limitations were common, particularly in smaller or open-label trials, the collective evidence remains credible and supports cautious confidence in the reported efficacy and safety outcomes.

Fig. 2.

Risk of bias assessment for systematic review on prebiotics, probiotics, and postbiotics for acne vulgaris

Discussion

Prebiotics

Across five studies, prebiotic supplementation yielded consistent yet modest clinical improvement in acne outcomes, with pooled lesion reductions of around −37%. Oral formulations containing oligosaccharides, inositol, and polyphenolic complexes improved both inflammatory and noninflammatory lesions.

The most comprehensive randomized controlled trials (RCTs) combined oral FOS/GOS, zinc, and niacinamide with a peptide-based topical regimen, showing additive benefit versus topical therapy alone (total lesion reduction −34% versus −28%) [17]. Other trials employing green-tea extract [20] and myoinositol-based herbal supplements (MBHS) [18, 19] corroborated these findings, highlighting antioxidant and anti-androgenic effects through SCFA-mediated signaling. Myoinositol regulates hormonal influences for acne mainly by decreasing testosterone levels [47]. Lu et al. observed a 41% reduction in total lesions and improved sebaceous lipid oxidation using green-tea-derived prebiotic extracts [20]. Inositol-based prebiotics achieved 46% inflammatory lesion reduction over 12 weeks. [19] Interestingly, Maloh et al. and Min et al. both compared oral prebiotics against oral probiotics. Maloh et al. found that both were efficacious in improving inflammatory and noninflammatory lesions in patients with noncystic acne [19]. After 8 weeks, noninflammatory lesion counts decreased by 49.2% and 62.1% in the synbiotic and MBHS group, respectively [19]. Min et al. also found that both the synbiotic and MBHS groups significantly decreased acne lesion counts, but built upon Maloh et al.’s findings and also measured impact on gut microbiome, SCFAs, and hormonal profiles, ultimately linking and correlating these mechanisms to acne improvement [18, 19]. Adverse events were minimal and consisted of occasional mild bloating and transient gastrointestinal discomfort.

Prebiotics support the growth of beneficial skin and gut microbes potentially by promoting commensal skin bacteria, inhibiting pathogenic species such as C. acnes, and exerting antiinflammatory and barrier-protective effects.

Probiotics

Probiotics demonstrated the strongest and most reproducible clinical efficacy among biotic therapies, with mean lesion reductions of –45% and inflammatory lesion reductions exceeding –60%. Both oral and topical probiotics were effective, though oral supplementation showed a nonsignificant trend toward stronger effect.

Key RCTs demonstrated synergistic effects when probiotics were combined with systemic antibiotics. In Atefi et al., doxycycline with oral probiotic therapy achieved greater than 50% lesion reduction and improved gastrointestinal tolerability relative to doxycycline alone [32]. L. plantarum MH-301 supplementation enhanced isotretinoin efficacy (total lesion reduction −71%, inflammatory lesion reduction −70%) while mitigating mucocutaneous side effects (skin barrier hydration, gastrointestinal symptoms) [32, 38]. Multistrain capsules containing Bacillus coagulans, B. licheiformis, and B. clausii reduced inflammatory lesions by 45% and improved skin barrier hydration [21]. It is theorized that probiotics improve skin barrier hydration through multiple mechanisms including modulation of the skin microbiome, enhancement of barrier protein expression, and production of bioactive metabolites that strengthen the stratum corneum structure and moisture retention capacity [48].

Topical probiotics, including live formulations of Lactiplantibacillus plantarum, Lactococcus ferment, and Enterococcus faecalis CBT SL-5, produced mean inflammatory lesion reductions > 50% across 4–8 weeks. [41, 44] Split-face designs confirmed superiority of probiotic creams over vehicle, showing decreased erythema, reduced C. acnes density, and improved IGA scores by 1–1.5 points [35, 40]. Adverse events were infrequent and mild (dryness, transient flushing), with no serious systemic reactions.

Potential mechanisms include restoration of microbial balance, antiinflammatory effects, and modulation of insulin sensitivity. Probiotics can influence glucose homeostasis through their multifaceted effects on the gut microbiota and host metabolism [49]. Probiotics may also enhance the efficacy and tolerability of conventional therapies when used in combination.

Postbiotics

Across seven postbiotic trials, we observed consistent improvements in acne outcomes, with signals of benefit for both inflammatory and noninflammatory lesions. Oral formulations appeared to produce stronger effects than topical ones, though between-group differences were not statistically significant, reflecting the heterogeneity and modest size of available studies. These pooled findings echo individual studies. Topical heat-treated Pediococcus acidilactici reduced comedones and sebum [45]. Lactiplantibacillus plantarum lysates improved barrier function and transepidermal water loss, with the E15 lotion achieving a GAGS reduction of −1 over 4 weeks [44]. Lactobacillus-fermented Chamaecyparis obtusa extract was superior to tea tree oil, a topical prebiotic, for both inflammatory and noninflammatory lesions [16]. LactoSporin 2% cream matched benzoyl peroxide for lesion reduction but reduced sebaceous secretion more effectively, with a mean IGA reduction of 1.8 and mild erythema and dryness reported [50]. Oral bacterial lysates improved clinical severity while normalizing the skin microbiome, consistent with the stronger oral signal in our pooled analysis [43].

Most topical studies were short (3–8 weeks) and modest in sample size, often open-label or split-face, limiting generalizability and inflating placebo-adjusted responses. Safety across trials was favorable, with topicals reporting only mild irritation and oral lysates showing no serious adverse events. Mechanistically, postbiotics appear to disrupt C. acnes biofilms, suppress lipase activity, and modulate cytokine pathways, aligning with the improvements observed across lesion types [51–53]. Oral formulations may extend these effects by engaging systemic host–microbe signaling through the skin–gut–microbiome axis [54]. A plausible mechanism is immune training, whereby bacterial lysates prime innate and adaptive responses to dampen the exaggerated inflammatory cascades central to acne pathogenesis [53, 55, 56]. Taken together, postbiotics appear biologically active and clinically safe, but the absence of statistically significant superiority over controls illustrates the challenge of small, heterogeneous acne trials. At present, they are best considered as adjuncts to established therapies such as benzoyl peroxide or antibiotics, with potential as alternatives in patients prioritizing tolerability. Larger, adequately powered randomized trials with standardized outcome reporting and longer follow-up are needed before postbiotics can be recommended as standalone treatments.

Conclusions

In this systematic review of 33 studies, prebiotics, probiotics, and postbiotics were safe and associated with clinically meaningful improvements in acne, with pooled mean total lesion reductions of −37.2%, −45.2%, and −49.5%, respectively, compared with −37% in controls. Within-group benefits were statistically significant across all categories, while between-group and route-of-administration differences were not. Probiotics currently have the most robust evidence base and can be considered as adjuncts to standard therapy, including topical and oral antibiotics and retinoids, or as standalone options in select patients perhaps preferring complementary or alternative treatments. Prebiotics offer modest benefits and may be suited to adjunctive or maintenance roles, particularly when gut dysbiosis is suspected. Postbiotics demonstrated the highest efficacy and at present are best positioned as adjuncts to conventional agents. Further research should prioritize strain- and metabolite-standardized formulations, head-to-head trials, and longer follow-up to establish durability and optimize dosing.

Author Contributions

All authors contributed substantially to this work. Jonette E. Keri conceived the study design, supervised the systematic review process, and contributed to the interpretation of the results. Peyton V. Warp conceived the study design, performed the literature search, data extraction, quality assessment, and wrote the first draft of the manuscript. Sophie M. Bilik performed data extraction, quality assessment, data analysis, and wrote the first draft of the manuscript. Lina M. Ferrari performed data extraction, quality assessment, and manuscript revision. Jonette E. Keri critically revised the manuscript for important intellectual content. All authors read and approved the final manuscript.

Funding

No funding or sponsorship was received for this study or publication of this article.

Data Availability

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.

Declarations

Conflict of Interest

The authors (Peyton V. Warp, Sophie M. Bilik, Lina M. Ferrari, Jonette E. Keri) declare that there is no conflict of interest regarding the publication of this article.

Ethical Approval

This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.