Finasteride was approved by the FDA and is indicated for the treatment of male pattern hair loss (MPB). Since 5 mg Finasteride is frequently used in the treatment of prostate diseases as well, extensive clinical studies were performed in order to address the efficiency and the side effects of the drug. Sometimes, Side effects for Finasteride include a higher chance of aggressive prostate cancer, erectile dysfunction, and loss of libido. It is not necessary after a hair transplant, but it is a good idea to ask your doctor why he prescribed it.