Dutasteride is a 5-Alpha Reductase Inhibitor medication that is being used off-label for male pattern hair loss. Dutasteride works on the scalp by blocking the enzyme which converts Testosterone to Dihydrotestosterone (DHT). It has been discovered that DHT can play a role in male pattern hair loss. Once DHT is indirectly blocked by Dutasteride, you may experience a reduction in hair loss and a general maintenance of the hair you currently have. Sometimes, Dutasteride will even regrow some of the lost hair, but the main goal is reducing additional hair loss.