Propecia contains a medicine called finasteride. This belongs to a group of medicines called Type II 5 alpha reductase inhibitors. Your doctor has prescribed Propecia because you have male pattern hair loss (also known s androgenetic alopecia). Propecia increases hair growth on the scalp & prevents further hair loss in men. Men with mild to moderate, but not complete hair loss, can benefit from using Propecia. Propecia lowers the levels of DHT (dihydrotestosterone) in the scalp. This helps to reverse the balding process, leading to an increased hair growth & prevention of further hair loss.