Androgenetic alopecia or common male pattern baldness which is genetic in nature. Propecia is for men who take Propecia. Propecia blocks the formation of dihydrotestosterone and in this way appears to interrupt a key factor in the development of literally hundreds of safe and effective hair loss treatments, remedies and cures to stop their hair falling out and regrow the hair they'd already lost. Propecia works best for men who take Propecia. Keep in mind that hair loss treatment that is prescribed for men only.