Effects of Finasteride
Finasteride blocks the action of an enzyme called 5-alpha-reductase. This enzyme changes testosterone to another hormone that causes the prostate to grow or hair loss in males. It will increase testosterone levels in the body, which decreases prostate size and increases hair growth on the scalp.
the synthesis of estrogenic steroids was blocked by inhibition of testosterone conversion into dihydrotestosterone using a 5 alpha-reductase inhibitor finasteride, suggesting that they are generated downstream of dihydrotestosterone
This in thoery must masculinize people who take it, but it instead femnizes them. Source.
Finasteride causes certain male individuals to show symptoms of demasculinization and feminization after exposure