The FDA approved finasteride to treat hair loss in male pattern baldness, and is registered in many countries under the trade name Propecia. Finasteride is an antiandrogen which acts by inhibiting 5-alpha reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT). It works by blocking the body's production of the male hormone.
Finasteride blocks an enzyme called 5-alpha-reductase, which is necessary to change testosterone to another hormone that causes the prostate to grow. As a result, the size of the prostate is decreased. The effect of finasteride on the prostate lasts only as long as the medicine is taken. If it is stopped, the prostate begins to grow again.
Finasteride tablets may be crushed to make them easier to swallow. You may have to take this medicine for at least 6 months to see the full effect. Do not stop taking this medicine without first discussing it with your doctor. A decrease in the amount of semen during ejaculation should not affect your sexual performance and is not a sign of any change in fertility.
Along with its needed effects, a medicine may cause some unwanted effects. Check with your doctor as soon as possible if any of the following side effects occur Breast enlargement and tenderness; skin rash; swelling of lips, Testicular pain.