Efficacy of topical cysteamine hydrochloride in treating melasma: a systematic review

Introduction Melasma remains a recurrent, chronic, therapeutically challenging, and psychologically burdening condition. Several different modalities and approaches have been utilized, and some with notable success to experimentally manage the condition. Cysteamines, with their depigmentation properties, have only recently been intensely studied. One such formulation is the topical 5% cysteamine hydrochloride, the structure of which is notably more stable and with a less foul odor than its prior counterparts. We, therefore, aimed to assess the efficacy of the mentioned formulation in the treatment of melasma. Methods The PubMed, SCOPUS, ISI Web of Science, and Embase, Cochrane, and Proquest databases were thoroughly searched for English studies evaluating the effects of the topical agent mentioned. Results Eight studies (five RCTs, two case reports, and one case series) were included after three rounds of screening, most of which were carried out in Iran. Statistical significance was noted when assessing decreased melanin content and satisfaction rates. Conclusions It appears that the cysteamine cream could be comparably efficient in treating melasma while accompanied only by minor and transient adverse events. However, current evidence is limited by insufficient sample size, long-term follow-up, and only to epidermal melasma, highlighting the need for appropriately designed randomized controlled clinical trials to draw a conclusive image of the cysteamine's role in treating this recalcitrant condition.