Drug-Induced Melasma in Patients on 5-Alpha Reductase Inhibitors: A Case Report

Introduction: Melasma is a chronic hyperpigmentation disorder with pathogenesis linked to hormonal mediation, ultraviolet and heat exposure, and genetic predisposition. Five-alpha reductase inhibitors (5-ARIs), including finasteride and dutasteride, are widely prescribed for treatment of benign prostatic hyperplasia (BPH) and off-label for androgen-mediated dermatologic conditions, yet pigmentary adverse effects are rarely reported. To date, only one case documenting melasma following 5-ARI use has been published. We report two additional cases of finasteride-induced melasma. Case Summaries: A 53-year-old woman with Fitzpatrick Skin Type V developed progressive cheek hyperpigmentation approximately 1 year after initiating oral finasteride for frontal fibrosing alopecia. Clinical evaluation supported a diagnosis of melasma. Finasteride was discontinued, and treatment with cysteamine 5% cream led to partial improvement within 5 months. A 66-year-old man with FST VI presented with 1 year history of melasma on his forehead and temples, unresponsive to multiple topical therapies. It was revealed he had been taking oral finasteride for approximately 10 years for treatment of BPH. He was diagnosed with 5-ARI-induced melasma. Therapy was modified to include cysteamine cream, glutathione cream, azelaic acid, and a retinoid, and he was referred to his urologist for evaluation of finasteride discontinuation. Conclusion: These cases expand the limited literature on finasteride-associated melasma and highlight that improvement may require both discontinuation of the drug and targeted melasma therapy. Clinicians should consider 5-ARI exposure when evaluating new-onset or refractory facial hyperpigmentation, particularly in individuals with darker skin types, as early recognition and medication review may help mitigate persistent pigmentation.