THE CURE INDEX
Helio Cure's evidence score based on human clinical trials for red light therapy.
Melasma is a common skin condition that causes brown or grey patches to form on the face.
A review of 5 human studies covering 140 participants found red light therapy to be effective for melasma. The CURE Index scored this condition 74 out of 100, indicating strong confidence.
Red light therapy was associated with lighter patches and a more even skin tone.
The 5 studies included 4 clinical trials and 1 observational study. All 5 reported effective outcomes.
The most cited wavelength was 675 nm, within a range of 628 nm to 950 nm. Sessions lasted up to 20 minutes, were given 3 to 36 times per week, and ran for 56 to 270 days.
EVIDENCE AT A GLANCE
The numbers behind the verdict.
MOST CITED WAVELENGTH
The wavelength appearing most often in studies that showed benefit for melasma.
675 nmTREATMENT PROTOCOL RANGES
The lowest and highest values used across melasma studies.
| PARAMETER | RANGE |
|---|---|
| Wavelength | 628-950 nm |
| Distance | Contact-0.98 inches |
| Session Frequency | 3-36 per week |
| Therapy Duration | 56-270 days |
Note: We have excluded meta-analyses and reviews from scoring, but the list of human studies below contains them for your reference.
6 Human Studies on Red Light Therapy for Melasma
Review Reported Laser Beneficial for Melasma and Acne
Across 4 skin conditions treated with the same wavelength, a 2025 review examined low-level laser therapy (LLLT) at 675 nm for signs of skin aging, melasma, acne and stretch marks. The review team searched PubMed for trials and reviews written in English, checked the reference lists of the studies they kept, and compared treatment plans, patient details and outcome measures across them. According to the review, light at this wavelength was linked to better skin texture and more collagen, and it appeared to help with melasma, acne and stretch marks. Side effects were described as minimal, and the authors called for more trials to pin down how the laser is best used.
- Study Type
- Review
- Treated Area
- Skin
- Wavelength(s)
- 675 nm
Study Title: Exploring the potential of the emerging 675 nm laser across diverse skin pathologies: a comprehensive review.
Significant Improvement Reported in Melasma and Wrinkles With LLLT
Among 30 Syrian women aged 25 to 50 with moderate to severe melasma and wrinkles, a 2024 clinical trial tested low-level laser therapy (LLLT) for skin rejuvenation. Participants were divided into 2 groups and treated with continuous-wave 660 nm light at 15.6 mW/cm². The researchers reported that skin showed a statistically significant improvement after treatment in both groups. No adverse effects were found, and the discoloration did not return during the study.
- Study Type
- Clinical Trial
- Participants
- 30
- Treated Area
- Skin
- Wavelength(s)
- 660 nm
Study Title: Low-level laser therapy for skin rejuvenation: A safe and effective solution baked by data and visual evidence.
3 Sessions of 675 nm Light Eased Facial Melasma
Delivering 3 sessions at 30-day intervals, a 2023 clinical trial tested a 675 nm laser device on facial melasma in women and men. 18 patients with lighter skin tones were treated over 60 days at 10 W using a scanning head measuring 13 by 13 mm, and improvement in appearance was rated on a standard 5-point scale 3 months after the final session. Appearance ratings appeared to improve, and the device seemed to help with both the discoloration and the visible blood vessels. The researchers described the approach as carrying no risk for these skin tones and pointed to the low energy used and the reduced inflammation seen afterward.
- Study Type
- Clinical Trial
- Participants
- 18
- Treated Area
- Face
- Wavelength(s)
- 675 nm
- Session Duration
- 0.15 seconds
- Session Frequency
- 3 per week
- Therapy Duration
- 60 days
Study Title: The 675-nm wavelength for treating facial melasma.
Observational Study Found 675 nm Laser Improved Melasma in Women
Scores measuring how severe the melasma was fell from 26.4 before treatment to 17.3 at 3 months after the final session, in a 2020 observational study of a new 675 nm laser system. 25 women aged 21 to 50 with facial melasma and lighter skin tones were treated by researchers in Italy in 3 sessions delivered in contact with the skin at 10 W. All 25 improved on that score, and the improvement was statistically significant. The authors concluded that the laser may be promising for harmless darkened patches of skin, with a low risk of side effects and simple aftercare. Side effects were limited to minor redness in 2 patients.
- Study Type
- Observational Study
- Participants
- 25
- Treated Area
- Face
- Wavelength(s)
- 675 nm
- Distance
- Contact
- Session Duration
- 0.1 seconds
- Session Frequency
- 3 per week
Study Title: A New 675 nm Laser Device in the Treatment of Melasma: Results of a Prospective Observational Study.
Women With Darker Skin Tones Showed Improvement in Melasma After LED Treatment
60 women aged 25 to 60 took part in a 2018 clinical trial of LED treatment for melasma on darker skin tones. Participants were placed into 2 groups according to their skin tone, and each group received 36 LED sessions over 270 days using 628 to 638 nm and 820 to 840 nm light, at 5 and 105 mW/cm² and 66 and 126 J/cm², in sessions lasting 20 minutes. Both groups improved on the subjective and objective measures used, and the trial found those improvements to be statistically significant.
- Study Type
- Clinical Trial
- Participants
- 60
- Treated Area
- Face
- Wavelength(s)
- 628-638, 820-840 nm
- Session Duration
- 20 minutes
- Session Frequency
- 36 per week
- Therapy Duration
- 270 days
Study Title: The Management of Melasma on Skin Types V and VI Using Light Emitting Diode Treatment.
Photobiomodulation Reduced Pigment on the Treated Side in Melasma
A split-face design treated 1 side of the face and left the other side untreated as a control, in a 2018 clinical trial of photobiomodulation (PBM) for melasma. 7 women with a mean age of 38 years took part, all with melasma on both sides of the face and all of whom had already tried skin creams and peels without success. They were given microdermabrasion followed by 930 to 950 nm light at 90 mW/cm² and 13.5 J/cm², in 5-minute sessions from a distance of 0.98 inches over 56 days. The treated side appeared to show a greater reduction in pigment than the untreated side, judged by a panel of 3 physicians who compared before and after photographs on a standard 4-point rating scale.
- Study Type
- Clinical Trial
- Participants
- 7
- Treated Area
- Face
- Wavelength(s)
- 930-950 nm
- Distance
- 0.98 inches
- Session Duration
- 5 minutes
- Session Frequency
- 8 per week
- Therapy Duration
- 56 days
Study Title: Dual Effect of Photobiomodulation on Melasma: Downregulation of Hyperpigmentation and Enhanced Solar Resistance-A Pilot Study.
The CURE Index (Clinical Understanding of Red-light Evidence) by Helio Cure is a 0-100 evidence score based on published human clinical trials. Higher scores mean stronger evidence. Read full methodology →
Data is powered by AI and reviewed by the Helio Cure team.
This page is for educational purposes only. Not medical advice. Consult a healthcare provider before starting red light therapy. Helio Cure does not diagnose, treat, or cure any medical condition.
Last updated: Oct 23, 2026