Learn about the side effects of finasteride, from common to rare, for consumers and healthcare professionals. 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. View finasteride information, including dose, uses, side-effects, monitoring requirements, important safety information and drug action. Finasteride (brand name Propecia) is a prescription medication used to treat male pattern baldness in adult men. It works by lowering levels of a hormone in your body that's linked to hair loss. You take it by mouth once a day, with or without food. Finasteride is used to treat an enlarged prostate. It's also used to treat hair loss in men, but this is not available on the NHS. Finasteride for hair loss is only available with a private prescription, so you'll need to pay for the full cost of the medicine. Finasteride works by reducing the amount of DHT available by blocking an enzyme called 5α-reductase, which converts testosterone into DHT. Lower levels of DHT help improve hair growth in male pattern hair loss and reduce symptoms of BPH. 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. 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. 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. What Is Finasteride and How Does It Work? 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.