How Finasteride Works
Finasteride's hair-raising success is due to its ability to specifically inhibit 5-alpha-reductase, the enzyme that converts testosterone into a more potent androgen dihydrotestosterone (DHT).
Propecia's 1 mg dose of finasteride can effectively lower DHT levels in the scalp by as much as 60% when taken daily. It is DHT that shrinks or miniaturizes the hair follicle, which eventually leads to baldness. This 60% reduction in DHT has proven to stop the progression of hair loss in 86% of men taking the drug during clinical trials. 65% of trial participants had what was considered a substantial increase of hair growth.
At this point, the only truly effective medically proven way to arrest the hair loss process is to lower DHT levels. The American Hair Loss Association recommends finasteride as the first line of attack for all men interested in treating their male pattern baldness.
Minoxidil was the first drug approved by the FDA for the treatment of male pattern baldness. For many years, minoxidil, in pill form (brand name Loniten), was widely used to treat high blood pressure. Just like finasteride, researchers discovered a very interesting side effect of the drug. People taking the medication were growing hair in unexpected places, such as on their cheeks and the back of their hands. Some people grew hair on their foreheads.
Some enterprising researchers had the notion that applying minoxidil topically, directly on the head, might grow hair on balding areas. It did, to varying degrees depending on the extent of the hair loss, but at the time it was revolutionary.
While minoxidil has been clinically proven to slow the progression of hair loss and regrow some hair, most experts see it as a relatively marginally effective drug in the fight against hair loss. Since minoxidil has no effect on the hormonal process of hair loss, its positive effects are at best temporary and usually yield somewhat disappointing results.
The American Hair Loss Association still recommends the drug for those who have not responded favorably to finasteride treatment or for those who would like to add another product to their regimen. The AHLA does not recommend minoxidil as the first line of attack for men suffering with male pattern baldness, but does recognize it as an effective treatment for a small percentage of its users.