Finasteride is a medication that treats the symptoms of an enlarged prostate and a condition called benign prostatic hyperplasia. It works by decreasing the size of your prostate. Finasteride is commonly used to treat BPH, which is non-cancerous enlargement of the prostate. In some people, BPH can occur at the same time as prostate cancer. Finasteride (Proscar, Propecia) is used to treat male pattern hair loss or benign prostatic hyperplasia. Learn about side effects, warnings, dosage, and more. Learn about the side effects of finasteride, from common to rare, for consumers and healthcare professionals. Finasteride is a 5-alpha reductase inhibitor. It blocks the body's production of a male hormone in the scalp that stops hair growth, thereby reversing the balding process and preventing further hair loss. Finasteride is a prescription medication used to treat Benign Prostatic Hyperplasia and Androgenic Alopecia in males. Finasteride is available under the following different brand names: Propecia, Proscar. Finasteride is from a class of medicines called 5α-reductase inhibitors. Finasteride 5mg tablets are used to treat symptomatic benign prostatic hyperplasia (BPH) in men, and finasteride 1mg tablets are used to treat male pattern hair loss in men. Finasteride is used to treat men who have symptoms of benign prostatic hyperplasia (BPH) and male pattern hair loss, also called androgenetic alopecia. BPH is caused by an enlarged prostate. I've been on Finasteride for 7 years, and I'm 29, no side effects I've noticed. My hair looks better today than when I started. I used to take 1.25mg a day, but now I only take 1.25mg 4 times a week. Taking finasteride leads to a reduction in scalp and serum DHT levels; by lowering scalp levels of DHT, finasteride can maintain or increase the amount of terminal hairs in the anagen phase by inhibiting and sometimes reversing miniaturization of the hair follicle.