Photothermal-Activated Platelet-Rich Plasma Versus Conventional Platelet-Rich Plasma for Melasma: A Split-Face, Double-Blind Randomized Controlled Trial.
BACKGROUND: Melasma is a common acquired pigmentary disorder that predominantly affects women with darker skin types and substantially impairs quality of life. Current treatments are limited by variable efficacy, adverse effects, and frequent recurrence. Platelet-rich plasma (PRP) has emerged as a potential regenerative treatment through growth-factor-mediated modulation of melanogenesis. Photothermal activation, which combines photobiomodulation with controlled hypothermic conditioning, has been hypothesized to promote a more sustained growth-factor release than conventional PRP. This study compared the efficacy and safety of photothermal-activated PRP (PT-PRP) and conventional PRP (C-PRP) for melasma treatment. METHODS: This split-face, double-blind, randomized controlled trial included 26 women with epidermal or mixed-type melasma. Each participant received three monthly sessions of intradermal PRP, with PT-PRP and C-PRP injected into opposite facial sides. Outcomes were assessed at weeks 0, 4, 8, and 12 using the modified Melasma Area and Severity Index (mMASI), Mexameter melanin and erythema indices, patient satisfaction, overall improvement, and adverse events. RESULTS: Both treatments significantly reduced mMASI by week 12, with no significant between-group differences at any time point. C-PRP showed significant mMASI improvement from week 4, whereas PT-PRP reached significance from week 8. For the melanin index, PT-PRP produced a significant within-group reduction at week 12, while C-PRP did not. At week 12, PT-PRP showed a significantly lower melanin index than C-PRP. Mild injection-site bruising was the only adverse event. CONCLUSION: PT-PRP and C-PRP produced comparable clinical improvement, but PT-PRP achieved greater objective melanin reduction at week 12. PT-PRP may represent a safe alternative treatment for melasma. TRIAL REGISTRATION: Thai Clinical Trials Registry: TCTR20260318004.