Finasteride  is a medication  use for to cure prostate  enlargement  and male pattern baldness.  It is a type of drug  known  as  5-alpha-reductase  inhibitor  which means that it work by blocking  the enzyme  that convert testosterone  to dihydrotestosterone (GHT) .  Dihydrotestosterone  is a hormone which is formed from testosterone . GHT is primarily  produce in prostate,  Hair follicles and testes. In prostate  it  stimulates  the growth  of  prostate  cell which can lead to   BPH in men. DHT bind to androgen receptor  of hair  follicles   which cause the follicles  to shrink , thinner and shorter which is the major cause of  Male  pattern baldness also known as  androgenic  alopecia. 

Finasteride is FDA approved  medication  for Male  pattern baldness  . It works  by  inhibiting  the enzyme  which convert testosterone  to dihydrotestosterone   which is a hormone that  mainly  responsible  for hair loss  in men.  By reducing  the DHT  level   in scalp  finasteride  can slow or  reverse  the hair loss  process. 

Finasteride  is not effective for  all  kind of hair loss and also not recommended  for women .

Finasteride  is available  in two  different  doses one is 1g and another one is 5g. The 5g finasteride dose is use for  the treatment of prostate  gland .( benign  prostatic  hyperplasia) while 1g dose is mainly  use for hair loss treatment ( male pattern baldness) . Generally  5g doses not recommended  for hair loss treatment  because of its higher   side effects.