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. 2025 Dec 10;16(1):617–627. doi: 10.1007/s13555-025-01613-w

Efficacy and Safety of 675-nm Laser Monotherapy for Melasma in Fitzpatrick Skin Types III–V: A Prospective Pre–Post Intervention Study

Panwadee Thongjaroensirikul 1, Ploypailin Tantrapornpong 1, Woramate Bhorntarakcharoen 1, Sariya Sittiwanaruk 1, Felix Paolo J Lizarondo 2, Woraphong Manuskiatti 1,✉
PMCID: PMC12872996  PMID: 41372602

Abstract

Introduction

Melasma is a chronic pigmentary disorder that often recurs after treatment, particularly in people with darker skin who are more prone to pigmentary side effects.

Methods

This prospective study evaluated the efficacy and safety of a 675-nm laser for melasma in individuals with darker skin types. Twenty-eight Thai women with Fitzpatrick skin types (FSTs) III–V underwent three monthly laser sessions using dual Moveo and Standard modes without anesthesia. Clinical severity, pigmentation, patient satisfaction, and safety were assessed up to 6 months after treatment.

Results

The modified Melasma Area and Severity Index (mMASI) showed a 41% improvement at 3 months and 34% at 6 months post-treatment. Antera 3D imaging confirmed progressive melanin reduction, and over 70% of participants reported at least 50% improvement. Adverse effects were mild and transient, including mild erythema or small scabs, with no postinflammatory hyperpigmentation (PIH) observed.

Conclusion

The 675-nm laser achieved sustained lightening of melasma and skin tone improvement with minimal discomfort and no downtime. These findings support the 675-nm laser as a safe and effective treatment for melasma in darker skin types, offering a potential new approach for managing this persistent condition.

Keywords: Melasma, 675-nm laser, Fitzpatrick skin types III–V, Photobiomodulation, Tyrosinase, Hyperpigmentation

Key Summary Points

Why carry out this study?
Melasma is a chronic, relapsing pigmentation disorder that commonly affects individuals with darker skin types, in whom postinflammatory hyperpigmentation remains a significant treatment challenge.
Conventional therapies often yield incomplete or temporary improvement, highlighting the need for safer and more durable treatment options.
What was learned from the study?
This study evaluated whether 675-nm laser monotherapy could effectively and safely improve melasma in patients with Fitzpatrick skin types III–V.
After three monthly treatment sessions, the 675-nm laser achieved a 41% reduction in the modified Melasma Area and Severity Index (mMASI) at 3 months and a 34% reduction at 6 months, with over 70% of patients reporting ≥ 50% improvement. Treatment was well tolerated and required no anesthesia.
These findings support the 675-nm laser as a promising, low-risk option for long-term melasma management in patients with Fitzpatrick skin types III–V.
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Introduction

Melasma is a chronic, relapsing pigmentary disorder presenting as irregularly shaped brown to grayish brown patches on sun-exposed areas of the face, particularly in individuals with Fitzpatrick skin types (FSTs) III–V [1]. While the etiology of melasma has not yet been fully elucidated, it is thought to involve various factors such as genetic susceptibility, hormonal changes, ultraviolet (UV) radiation, visible light (VL), and certain medications [2, 3]. Rather than just a primary disorder of melanocytes, melasma is now being thought of as a photoaging disorder wherein various cells such as fibroblasts, endothelial cells, mast cells, and sebocytes contribute to the solar elastosis, basement membrane alteration, and increased vascularization ultimately leading to increased melanin production [4–6]. The complex interplay of these factors underlies the challenge of treating melasma.

Consistent photoprotection against UVB, UVA1, and high energy VL (HEVL) is a cornerstone of melasma management [7]. Primarily targeting melanin production, the triple combination cream (TCC), which contains varying concentrations of hydroquinone (HQ), retinoids, and steroids, is still considered the gold standard of treatment although recurrence occurs upon discontinuation [3, 8, 9]. While alternative topical skin-lightening agents such as kojic acid, arbutin, and azelaic acid can be utilized, clinical responses are variable and recurrence is also an issue with cessation of therapy [3, 8].

Adjunctive therapies including intralesional or oral administration of tranexamic acid, which targets melanogenesis and angiogenesis, and chemical peels, which promote melanin exfoliation may be undertaken; however, responses are often partial and recurrence remains common [3]. Additionally, orally administered tranexamic acid carries potential risks, such as thromboembolic events, particularly in patients receiving hormonal therapy [8].

Lasers and energy-based devices (EBDs) have also been investigated since they can target key pathogenic components of melasma including pigmentary, vascular, and photoaging domains [8, 10]. However, treatment responses are variable, recurrence is common, and adverse effects including hyperpigmentation and hypopigmentation remain a concern [8].

The 675-nm laser is a novel treatment modality for melasma. Being well within the absorption spectrum of melanin, the 675-nm laser can be considered a pigment laser [11]. Since this laser operates within the red light spectrum of 620–700 nm, it can improve pigmentation by a process called photobiomodulation (PBM), wherein melanogenesis is reduced by inhibiting tyrosinase (TYR) activity [12, 13]. Moreover, the effects of the nonablative 675 nm laser on dermal remodeling can possibly address the photoaging aspects of melasma [14, 15]. Prior prospective studies done in Italy have shown that the 675-nm laser treatment improves melasma for up to 3 months in patients with FSTs II–V, with only minimal adverse effects such as transient erythema and occasional rebound hyperpigmentation [11, 16, 17]. Sustained clinical improvement for up to 1 year was also demonstrated in eight Italian patients with melasma who received three monthly 675-nm laser treatments [18].

The current study aimed to evaluate the long-term efficacy and safety of the 675-nm laser for melasma in Thai patients using both subjective and objective assessments.

Methods

Study Design

This prospective study was conducted at a tertiary academic skin laser center of a university hospital. The study protocol was approved by the Siriraj Hospital Institutional Review Board, Mahidol University, Bangkok, Thailand (Si 025/2024) and was registered at Thaiclinicaltrials.org online registry (TCTR20250317012). Written informed consent was obtained from all participants before entering the study. Written consent to publish participants’ photographs was obtained.

Participant Selection

Thai patients aged more than 18 years old with FSTs III–V, presenting with mixed-type melasma determined by Wood’s lamp examination were considered eligible for the study. Inclusion criteria were as follows: volunteers having bilateral lesions and a modified Melasma Area and Severity Index (mMASI) score with homogeneity, darkness, and area involvement scores at least 2. Patients who were using bleaching creams, had undergone chemical peels, intralesional tranexamic acid injection, and/or laser treatments within the past 6 months, who were pregnant or breastfeeding, and those on orally administered tranexamic acids and/or oral contraceptive pills were excluded from the study. The use of oral or topical treatments for melasma was not permitted during the study period.

On the basis of a prior study [17], we assumed a mean change from baseline to 3 months of 10 and an SDpooled of 15, yielding an effect size of 0.667. With 90% power, a two-sided significance level of 0.05, and a 5% anticipated dropout, the minimum sample size calculated was 28 patients.

Intervention

All participants received three monthly treatments of a 675-nm laser (RedTouch®, DEKA M.E.L.A., Calenzano, Italy). No topical anesthesia was applied prior to the treatment. A thin layer of aqueous, transparent, non-colored gel was applied to the treatment surface before starting the treatment to allow smooth gliding of the sapphire tip of the laser handpiece. The study device emitted a 675-nm wavelength and was equipped with a 15 × 15 mm scanning system with a contact sensor integrated into a water-cooled handpiece, capable of generating fractional micro-zones (DOTs) measuring 0.7 mm in width. Each session employed two laser delivery modes including Moveo and Standard. In Moveo mode, a power of 4 W, dwell time 50 ms, DOT energy of 0.2 mJ, DOT fluence of 52 J/cm2, and 8% density with epidermal cooling of 5 °C was used to treat the entire face by delivering 2000 DOTs per cheek and 500–1000 DOTs to the forehead, depending on forehead size. The handpiece was placed in contact with the skin surface, without excessive pressure, using consecutive, non-overlapping spots over affected areas. Subsequently one pass of a Standard mode was then applied to melasma lesions with a power of 5 W, dwell time of 75 ms, DOT energy of 0.4 mJ, DOT fluence of 97 J/cm2, and 1.7% density with epidermal cooling of 5 °C for all subjects. The therapeutic endpoints were mild to moderate erythema and a mild warm sensation, both lasting several minutes.

No special postoperative care was required. All participants were instructed to use a broad-spectrum sunscreen with SPF 50 and maintain their regular daily activities throughout the study period.

Outcome Measurements

Treatment outcomes were evaluated using both objective measurements and subjective patient-reported outcomes. Assessments were performed at six standardized time points: baseline (prior to treatment), 1 month after each of the three treatment sessions, and at 3 and 6 months after completion of all treatments.

The primary outcome was clinical improvement in melasma severity, measured using the mMASI [19]. This validated scoring system quantifies melasma on the basis of its distribution and intensity across facial regions, producing a composite score derived from the affected area, pigmentation darkness, and homogeneity.

Secondary outcomes included objective assessment of skin pigmentation, along with patient-reported improvement and treatment tolerability. Pigmentation was quantified using a skin imaging device (Antera® 3D CS, Miravex Limited). Measurements were obtained at standardized anatomical sites at each visit and averaged over three consecutive readings to ensure reliability.

Patient-perceived improvement was assessed using the Patient Improvement Scale, a 5-point categorical tool in which participants rated their improvement as 0% (none), 1–25%, 26–50%, 51–75%, or 76–100%. Pain was evaluated immediately after each session using a visual analog scale (VAS) from 0 (no pain) to 10 (worst imaginable pain), with scores recorded separately for the Moveo and Standard modes to compare tolerability. Adverse events and treatment-related side effects were actively monitored and documented throughout the study period.

Statistical Analysis

Changes in outcome measures over time were evaluated using mixed-effects repeated-measures models (REML) to account for within-subject correlations and missing data. Statistical significance was set at a two-sided p value < 0.05. Categorical variables, including patient-reported improvement, were summarized descriptively using frequency distributions.

Results

A total of 28 female Thai participants were enrolled, with a mean age of 49.00 ± 5.74 years. All had FSTs III–V, predominantly type IV (n = 24; 85.71%), followed by type V (n = 3; 10.72%) and type III (n = 1; 3.57%). Twelve participants (42.86%) were postmenopausal. All completed follow-up visits at 1 and 6 months post-treatment. Two participants (7.14%) were unable to follow-up at the 3-month visit, yielding 26 complete datasets for that time point.

The baseline mean mMASI score was 25.56 ± 7.63. Significant reductions were observed at all post-treatment time points: 20.56 ± 7.49 after the first treatment (− 19.57%, p < 0.0001), 16.28 ± 6.42 after the second (− 36.34%, p < 0.0001), 15.05 ± 7.12 after the third (− 41.11%, p < 0.0001), 15.09 ± 7.56 at 3 months post-treatment (− 40.96%, p < 0.0001), and 16.94 ± 8.76 at 6 months (− 33.74%, p < 0.0001) (Fig. 1). A mixed-effects repeated-measures model (REML) confirmed a significant time effect (p < 0.0001), indicating sustained improvement with only minor rebound at the final follow-up. Representative clinical outcomes are shown in Figs. 2 and 3.

Fig. 1.

Fig. 1

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Modified Melasma Area and Severity Index (mMASI) at baseline; 1 month after each treatment (Tx); and at 3 and 6 months following the final Tx. *Statistically significant difference compared with baseline

Fig. 2.

Fig. 2

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Thirty-six-year-old Thai woman (Fitzpatrick skin type III). Baseline (a) and 6 months after three sessions of 675-nm laser treatment (b)

Fig. 3.

Fig. 3

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Fifty-year-old Thai woman (Fitzpatrick skin type IV). Baseline (a) and 6 months after three sessions of 675-nm laser treatment (b)

Antera 3D imaging revealed a consistent reduction in melanin levels within the melasma-affected cheek area, decreasing from 0.81 ± 0.07 at baseline to 0.80 ± 0.06 after the first treatment (p = 0.2156) becoming statistically significant at 0.79 ± 0.06 after the second (p = 0.0296), 0.79 ± 0.07 after the third (p = 0.0013), 0.78 ± 0.07 at 3 months (p < 0.0001), and 0.76 ± 0.07 at 6 months (p < 0.0001), as shown in Fig. 4.

Fig. 4.

Fig. 4

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Melanin levels measured with the Antera® 3D CS imaging system at each visit. Tx, treatment. *Statistically significant difference compared with baseline

Subjective improvement was assessed using the Patient Improvement Scale. At 1 month after the third treatment, most participants (25%) reported a 26–50% improvement. By 3 and 6 months post-treatment, 58% and 43% of participants, respectively, rated their improvement at ≥ 51%, with approximately 30% reporting a 76–100% improvement at the 6-month follow-up.

Mean of pain scores were 0.63 ± 1.17 and 1.51 ± 1.45 in Moveo and Standard modes, respectively. No serious adverse events occurred during the study. Mild, transient side effects were observed in a few cases. After the first session, two participants developed mild erythema that resolved within 2 days, and one developed a small scab that healed within 3 days without sequelae. Following the second session, one participant also experienced erythema which lasted for 2 days.

Discussion

This study demonstrated that the 675-nm laser can provide sustained improvement of melasma without any major adverse events. Patients showed significant improvement in their mMASI scores after three monthly treatment sessions, decreasing by 41% and 34% at 3 and 6 months, respectively. This was also substantiated by the decreasing melanin level measurements using Antera 3D imaging system and 43% of patients reporting ≥ 51% improvement of their lesions at the 6-month follow-up period. These results align with prior studies done on the efficacy of 675-nm laser treatment for melasma [11, 16, 17, 20]. Nisticò et al. [17] reported a 34% reduction in the baseline MSI score, from 26.4 ± 19.2 to 17.3 ± 15.0, at 3 months after three monthly sessions of 675-nm laser treatment in 25 subjects with FSTs I–III. Another study involving 15 patients with FSTs IV–V, the mean improvement at 3 months following three 675-nm laser sessions was 3.1 ± 0.7 on a 5-point scale [11]. In a study on 18 patients with melasma and FSTs II–III, on a scale of Global Aesthetic Index of 0–4, improvement was rated as follows for photos taken with visible light, pigment, and vascular views: 1.89 (± 0.96), 2.28 (± 0.67), and 2.17 (± 0.79), respectively after 3 months [16]. A case series with three Indonesian patients with FSTs IV–V noted a 50% improvement mMASI at 3 months after three monthly sessions of 675-nm laser treatment [20].

Since the 675-nm laser operates well within the absorption spectrum of melanin, it can be classified as a pigment laser [11]. Of note, this shorter wavelength has a higher affinity for melanin, necessitating adjustments for use with darker skin types. A dual-mode protocol was used in this study wherein the Moveo mode provided fractionated low-fluence, large-area coverage of the entire face and the Standard mode delivered fractionated, higher-fluence to target focal pigmentation. This protocol was modified from the case series that reduced the fluence and dot density in Indonesian patients with darker skin types that mitigated treatment-related risks, consistent with established safety recommendations for skin of color [20].

Another possible mechanism by which the 675-nm laser improves melasma is via the process termed photobiomodulation (PBM). It has recently been coined to more accurately describe the technique involving low-intensity lasers or LEDs [21]. It is believed that the low‑level 675‑nm laser exerts its PBM action by inhibiting melanogenesis by interfering with TYR activity. The observed melanin reduction was associated with a reduction in TYR activity after PBM with 660 nm LED light (10 J/cm2), as well as after repeated irradiation at 830 nm (20 J/cm2) and 850 nm (1 J/cm2) [12, 13]. Interestingly, an in vivo evaluation identified that LED light at 660 nm (10 and 20 J/cm2) was also effective in reducing melanin synthesis in hyperpigmentation induced by UVB radiation [13]. With the 675-nm laser used in this current study, the PBM effect can be achieved with the low-fluence Moveo mode which works synergistically with the photothermal reaction elicited with the high-fluence Standard mode.

With melasma now being viewed as a photoaging disorder, the effect of 675-nm laser on dermal remodeling can also explain results seen in this study. Prior studies have shown that the 675-nm laser therapy can improve facial wrinkles and acne scars, demonstrating its efficacy in improving skin texture [22, 23]. Histologic studies have demonstrated that the 675-nm wavelength induces new collagen formation in treated skin compared to controls [14, 15]. While detailed assessment of textural and laxity outcomes was beyond the primary objectives of this study, approximately 50% of participants in our cohort exhibited gradual improvement of skin texture of the mid-face and lower-face contours at 3 and 6 months after the final treatment (Fig. 5).

Fig. 5.

Fig. 5

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Skin texture and tone maps for the patient in Fig. 3. Baseline (a) and 6 months after three sessions of 675-nm laser treatment (b)

The outcomes observed in this study on the 675-nm laser add to the growing body of evidence that lasers can improve melasma as monotherapy. A meta-analysis on laser treatments for melasma found that decreased Melasma Area and Severity Index (MASI) was seen in laser interventions such as low-fluence 1064-nm QSNY laser and fractional ablative lasers (AFL) such as CO2 and 2940-nm Er:YAG laser [10]. Another meta-analysis ranked the laser and light-based therapies in decreasing order of efficacy: 1064 QSNY laser, IPL and AFL more than TCC [8].

Additionally, the results of this current study done on the 675-nm laser are comparable with other studies that utilized a modified version of MASI in their scoring system. A retrospective series showed a 33% mMASI reduction (from 5.27 ± 2.47 to 3.54 ± 2.18) 2 weeks after nine sessions of low-fluence 1064-nm QSNY laser, with improvement maintained over 1 year [24]. A prospective split-face study in 30 women with melasma found significant hemi-MASI and dermoscopic improvements in both fractional non-ablative 675-nm diode laser and low-fluence 1064-nm QSNY without significant adverse events, with a trend to having more improvement in hemi-MASI and dermoscopic scores in the 675-nm laser [25]. In a prospective study of IPL, mean mMASI decreased by 45% (from 14.9 ± 3.6 to 8.2 ± 1.9) at 6 months following seven treatment sessions [26]. Similarly, a prospective trial of a 755-nm picosecond laser reported a 32% mMASI decrease (from 20.89 ± 8.62 to 14.26 ± 6.66) at 16 weeks after three sessions at 4-week intervals [27]. Of note, while these data are promising, combination treatments are still deemed more effective than any single treatment [8].

No serious adverse effects were observed with the 675-nm laser in this study. This is consistent with the favorable safety profile reported for IPL in melasma [8, 26]. In contrast, a serious adverse event that can be seen with low-fluence 1064-nm QSNY laser is mottled hypopigmentation, with reported rates of high as 14%, of which risk factors include short treatment intervals, higher fluence, and increased cumulative treatment sessions [28, 29]. In addition, postinflammatory hyperpigmentation (PIH) has also been reported with low-fluence QSNY as well as in picosecond lasers and AFL [8, 10].

This study has several limitations. First, because all participants received the same intervention without a comparator arm, the study functions as a single-arm before–after design, limiting causal inference. Second, the sample was small and homogeneous (28 female Thai participants, predominantly FST IV), limiting generalizability to other sexes, ethnicities, and skin types. Finally, efficacy was evaluated only up to 6 months, and a minor rebound was noted at the last visit, underscoring the need for longer-term follow-up to assess longevity of the results and relapse rates.

Conclusions

This study demonstrated that the 675-nm laser is effective in treating melasma in Thai patients without serious adverse events. Moreover, the treatment was well tolerated, required no anesthesia, and involved no downtime.

Author Contributions

Woraphong Manuskiatti and Panwadee Thongjaroensirikul had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Concept and design: Woraphong Manuskiatti and Panwadee Thongjaroensirikul. Acquisition, analysis, or interpretation of data: Ploypailin Tantrapornpong, Woramate Bhorntarakcharoen and Sariya Sittiwanaruk. Drafting of the manuscript: Panwadee Thongjaroensirikul. Critical review of the manuscript for important intellectual content: Woraphong Manuskiatti and Felix Paolo J. Lizarondo. Discussion: Woraphong Manuskiatti, Panwadee Thongjaroensirikul and Felix Paolo J. Lizarondo. Conclusion: Woraphong Manuskiatti and Panwadee Thongjaroensirikul. Supervision: Woraphong Manuskiatti.

Funding

No funding or sponsorship was received for this study or publication of this article. The Rapid Service Fee was funded by the authors.

Data Availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Conflict of interest

All authors (Panwadee Thongjaroensirikul, Ploypailin Tantrapornpong, Woramate Bhorntarakcharoen, Sariya Sittiwanaruk, Felix Paolo J. Lizarondo, and Woraphong Manuskiatti) declare no conflicts of interest.

Ethical Approval

The study protocol was approved by the Siriraj Hospital Institutional Review Board, Mahidol University, Bangkok, Thailand (Si 025/2024) and was registered at Thaiclinicaltrials.org online registry (TCTR20250317012). Written informed consent was obtained from all participants before entering the study. Written consent to publish participants’ photographs was obtained.

Footnotes

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

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