General Information

Propecia (finasteride) is a 5α-reductase inhibitor.

Propecia is specifically indicated for the treatment of male pattern hair loss (androgenetic alopecia).

Propecia is supplied as tablets. Propecia may be administered with or without meals. One tablet (1 mg) taken once daily. In general, daily use for three months or more is necessary before benefit is observed.

Mechanism of Action

Finasteride works by blocking an enzyme called 5-alpha reductase, which is responsible for the formation of dihydro-testosterone in a man's body. The enzyme converts testosterone to DHT, and it is believed that DHT is a key factor in male pattern hair loss. Finasteride decreases the concentration of DHT in a man's scalp by about two-thirds.

Side Effects

Adverse effects associated with the use of Propecia may include, but are not limited to, the following:

• diminished desire for sex
• difficulty achieving an erection and/or a decreased amount of semen 

Clinical Trial Results

In men with mild to moderate hair loss, clinical trials showed that 83% of the male patients had kept their hair or grown more after one year of treatment.