Finasteride is an oral (and increasingly topical) drug that blocks 5-alpha-reductase, cutting DHT and thereby slowing follicle miniaturization and partially regrowing hair. It is FDA-approved for male androgenetic alopecia at 1 mg/day and requires continued use to maintain results. A minority of men report sexual side effects; it is not used in women who may become pregnant.
Related terms
- DHT
- A potent androgen made from testosterone that miniaturizes scalp follicles in pattern hair loss.
- Minoxidil
- A topical (or off-label oral) treatment that prolongs the hair growth phase; OTC for pattern hair loss.
- Androgenetic alopecia
- The most common cause of hair thinning, driven by genetics and DHT sensitivity.