Objective: To assess the efficacy and safety of topical 5% cysteamine versus 4% hydroquinone in the treatment of facial melasma in women. Topical 5% cysteamine is an antioxidant and tyrosinase inhibitor that has been shown to be effective in the treatment of melasma. However, to date, no study has compared the performance of topical cysteamine to hydroquinone for facial melasma.

Methods: A quasi-randomized, multicenter, evaluator-blinded clinical trial was conducted on 40 women with facial melasma who were submitted to the nightly application of 5% cysteamine (CYS) or 4% hydroquinone (HQ) on hyperpigmented areas for 120 days. Both groups were required to use tinted sunscreen (SPF 50; PPD 19). Subjects were assessed at the inclusion and after 60 and 120 days of treatment for mMASI, MELASQoL, and the difference in colorimetric luminosity between melasma and the adjacent unaffected skin. The Global Aesthetic Improvement Scale was used to assess the difference in the appearance of the skin through standardized photographs.

Results: The mean reduction of the mMASI scores was 24% for CYS and 41% for HQ (P = 0.015) at 60 days, and 38% for CYS and 53% for HQ (P = 0.017) at 120 days. The photographic evaluation revealed up to 74% improvement for both groups, without statistically significant difference between them (P = 0.087). The MELASQoL score showed a progressive decrease for both groups over time, despite the greater reduction for HQ after 120 days (P = 0.018). Colorimetric assessment disclosed progressive depigmenting in both groups, without statistically significant difference between them (P > 0.160). No severe adverse effects were identified in either group. Erythema and burning were the most important local adverse effects with cysteamine, although their frequency did not differ between groups (P > 0.170).

Conclusion: Cysteamine proved to be safe, well-tolerated, and effective, despite its inferior performance to hydroquinone in decreasing mMASI and MELASQoL in the treatment of melasma.