5α-Reductase Inhibitors: Finasteride and Dutasteride in Feminizing Therapy

The review evaluates the use of 5α-reductase inhibitors, finasteride and dutasteride, in feminizing hormone therapy, noting their limited effectiveness due to partial inhibition of testosterone conversion to DHT and lack of significant feminizing benefits. These inhibitors do not reduce testosterone production or block androgen receptors, and there is no controlled trial support for their use in transfeminine individuals. Their primary application is for treating scalp androgenetic alopecia, while other uses are speculative. Safety concerns include psychiatric and sexual side effects, teratogenicity, and PSA suppression, prompting regulatory warnings. The WPATH SOC8 advises against their routine use in feminizing therapy due to insufficient data and potential risks.