Anti-androgen drugs work by blocking the effect of testosterone. This
reduces “male” physical traits and has a mildly “feminizing” effect. For
example, they will help slow “male”-pattern baldness, reduce growth of
facial hair, and stop spontaneous/morning erections. There are different
types of anti-androgens. The ones most typically prescribed to MTFs are
spironolactone (Aldactone®) and finasteride (Proscar®). Cyproterone
(Androcur®) can be used, but risks include depression and liver enzyme
elevation so spironolactone is generally preferred.
Anti-androgen drugs are often prescribed in addition to estrogen, as the
two have effects that complement each other. Taking anti-androgens
reduces the amount of estrogen you need to get the same effects, which
minimizes the health risks associated with high doses of estrogen. Antiandrogen
drugs can be prescribed alone for MTFs who want to reduce
“masculine” characteristics for a more androgynous appearance, as it’s
less “feminizing” than estrogen.