Currently, two medications are approved by the FDA for the treatment of hair loss: finasteride (Propecia®) and minoxidil (Rogaine®). Finasteride is an oral medication that is successful in retarding hair loss in men. In some patients, it will actually thicken existing hair and regrow hair that appears to have been lost. The drug works by reducing the levels of DHT in your body, a hormone that causes hair loss. Dutasteride is another effective DHT blocker that is also used (off-label).
Minoxidil is available as a topical solution for use by both men and women, and can also be taken orally (off-label). Minoxidil works by directly stimulating hair growth.
These drugs are most effective in patients who are thinning and not already bald. If successful, they need to be continued indefinitely. Most hair regrowth occurs on the back of the head (crown), but improvement can also be seen in the front (hairline) and mid-scalp.
There is also some evidence to suggest that shampoos containing either zinc pyrithione or ketoconazole may be effective in retarding hair loss by reducing inflammation in the scalp.