Efficacy and safety of topical 3% minoxidil for facial hair enhancement in transmen: a randomized, double-blind, placebo-controlled trial

Objectives Facial hair development is a crucial aspect of gender affirmation for transgender men. Despite testosterone therapy, incomplete facial hair growth remains a common concern. This randomized, double-blind, placebo-controlled trial evaluated topical 3% minoxidil for facial hair enhancement in 69 transgender men on stable gender-affirming hormone therapy (GAHT).Methods This randomized, double-blind, placebo-controlled trial enrolled 69 transgender men on stable GAHT, registered on the Thai Clinical Trials Registry (TCTR20220205004). Participants were randomized 1:1 to receive topical 3% minoxidil or vehicle placebo twice daily for 12 weeks. Primary outcomes were changes in hair density and diameter assessed via videodermoscopy. Secondary outcomes included modified Ferriman-Gallwey Score (mFGS), Dermatology Life Quality Index (DLQI), and patient satisfaction.Results The minoxidil group (n = 34) demonstrated significant improvements versus placebo (n = 35) in beard density (11.16 vs. 0.08 hairs/cm2, p = 0.01), beard diameter (5.37 vs. −0.33 μm, p = 0.01), mustache density (18.45 vs. 1.74 hairs/cm2, p = 0.003), and mustache diameter (4.83 vs. 1.31 μm, p = 0.008). Physician and patient-assessed mFGS showed significant improvements with minoxidil (p < 0.05). Quality of life improved markedly (median DLQI: 5 to 1.5 vs. 4 to 3, p < 0.05), with higher patient satisfaction scores (8.16 vs. 5.36, p < 0.001). Adverse events were minimal and comparable between groups.Conclusions Topical 3% minoxidil represents an effective, safe, and well-tolerated adjunctive treatment for facial hair enhancement in transgender men receiving GAHT.