Efficacy of topical minoxidil in enhancing beard growth in a group of transgender assigned female at birth individuals on gender affirming hormone therapy

Purpose Testosterone therapy represents the cornerstone of gender affirming hormone therapy (GAHT) among t-AFAB (transgender Assigned Female At Birth) people. Minoxidil is a vasodilator drug approved for topical use for the treatment of androgenetic alopecia. The aim of the present study was to evaluate the efficacy of topical minoxidil in enhancing beard growth in a group of t-AFAB people on GAHT.Methods Sixteen t-AFAB individuals with an incomplete beard development, on GAHT for at least 6 months, were enrolled. Topical minoxidil was applied to the interested facial areas. Before starting (T0), after 3 (T3) and 6 (T6) months, we evaluated facial hair growth using the Ferriman-Gallwey modified score (FGm).Results Subjects were 26 (2.7) years old and on GAHT for 18.5 [15-54] months; using a paired match evaluation, a statistically significant facial hair growth was observed over time, in particular at T6 (median upper lip FGm 3.5 [3-4] vs 2 [1-2] at T0 and chin FGm 4 [3.25-4] vs 1 [1-2] at T0; p <= 0.002). Comparing the minoxidil group with a control group (n = 16) matched for age and BMI who developed a full-grown beard only with GAHT, a logistic multivariable analysis identified hirsutism before GAHT was independently positively associated with the development of a full beard [OR 15.22 (95% CI 1.46-158.82); p = 0.023].Conclusions This is the first study demonstrating the efficacy of topical minoxidil in enhancing facial hair growth among t-AFAB people on GAHT. Further studies will be necessary to assess whether the obtained improvements will persist after discontinuing the medication.