Finasteride (Proscar) is used alone or in combination with another medication (doxazosin [Cardura]) to treat benign prostatic hypertrophy (BPH, enlargement of the prostate gland). Finasteride is used to treat symptoms of BPH such as frequent and difficult urination and may reduce the chance of acute urinary retention (sudden inability to urinate). It also may decrease the chance that prostate surgery will be needed. Finasteride (Propecia) is also used to treat male pattern hair loss (gradual thinning of the hair on the scalp, leading to a receding hairline or balding on the top of the head in men.) Finasteride (Propecia) has not been shown to treat thinning hair at the temples and is not used to treat hair loss in women or children. Finasteride is in a class of medications called 5-alpha reductase inhibitors. Finasteride treats BPH by blocking the body's production of a male hormone that causes the prostate to enlarge. Finasteride treats male pattern hair loss by blocking the body's production of a male hormone in the scalp that stops hair growth.