This drug prevents the conversion of the hormone DHT from testosterone. DHT causes susceptible hair follicles to slowly become dormant by shortening the growth phase, decreasing follicle size, and miniaturization of hair shafts. After 5 years of treatment, 90% of men halted their hair loss and 48% grew new hair. Patients must take this medication for at least a year to see its effectiveness. As with Minoxidil, cessation of this medication will cause the hair loss to return to pre-treatment stages and usually more pronounced seeing as hair loss would have progressed during the treatment period. This drug, unlike Rogaine does not stimulate hair growth, it prevents hair loss, therefore it can be used with Rogaine to have a two-pronged treatment of hair loss.
Propecia is a pill, and therefore can have side effects throughout the body. Sexual dysfunction that is reversible can occur when the medication is stopped. Breast enlargement has been reported as well as breast tenderness. PSA levels can be reduced in 50% of men which is important when screening for prostate cancer. Your physician should be made aware if you are taking this medication. Propecia has been shown to decrease the likelihood of prostate cancer, but the tumor grade may increase.
Propecia has not been FDA approved for women and has shown no effect on post menopausal women. Finasteride is a great adjuvant treatment in conjunction with hair replacement.