But not every side effect is a bad one. Some are downright welcome. Take finasteride . Introduced in 1992 to treat noncancerous enlargement of the prostate gland , it was found to regrow hair (and is marketed for that purpose under the name Propecia). Today, millions of men use a low dose of finasteride to treat male pattern baldness . Similarly, minoxidil , originally marketed as an oral tablet for high blood pressure , was found to grow hair in those using it. Today, as a topical lotion or foam, it is a popular over-the-counter remedy for baldness.