Finasteride is an antiandrogen which acts by inhibiting type II 5-alpha reductase.It is used as a treatment in
benign prostatic hyperplasia (BPH) in low doses, and prostate cancer in higher doses. It is also indicated for use in combination with doxazosin therapy to reduce the risk for symptomatic progression of BPH. Additionally, it is registered in many countries for androgenetic alopecia (male-pattern baldness).raw Finasteride powder

Finasteride was approved initially in 1992, a treatment for prostate enlargement, but the sponsor had studied 1 mg of finasteride and demonstrated hair growth in male pattern hair loss. On December 22, 1997, the FDA approved finasteride to treat male pattern hair loss.
Benign prostatic hyperplasia
Physicians use finasteride for the treatment of BPH, informally known as an enlarged prostate. The FDA-approved dose is 5 mg once a day. Six months or more of treatment with finasteride may be required to determine the therapeutic results of treatment. If the drug is discontinued, any therapeutic benefits reverse within about –8 months. Finasteride may improve the symptoms associated with BPH such as difficulty urinating, getting up during the night to urinate, hesitation at the start of urination, and decreased urinary flow.

Male pattern baldness
Finasteride is used to treat male pattern hair loss (androgenetic alopecia) in men only. Treatment provides about 30% improvement in hair loss after six months of treatment, and effectiveness only persists as long as the drug is taken.

Off-label uses
Finasteride is sometimes used in hormone replacement therapy for male-to-female transsexuals in combination with a form of estrogen due to its antiandrogen properties. However, little clinical research of finasteride use for this purpose has been conducted and evidence of efficacy is limited.