Medicine should be used at the beginning of hair loss.teatment. FDA(food and drug administration)see http://www.fda.gov has approved the use of finasteride (propecia, proscar) and minoxidil (rogaine)for hair loss treatment.For the approvals http://www.fda.gov/cder/foi/anda/2001/75-839_Minoxidil.pdf
http://www.fda.gov/cder/foi/nda/97/20180-S017_PROSCAR.PDF
you may visit the web sites above
In fact, medication is used for saving existing hair instead of gaining new ones..It is important to begin the medication as soon as possible.
In some cases medication bcan be combined with hair transplant.Physcian should decide.With hair transplant both  hair loss and having new hair is possible.
This part will be about hair loss, exact mechanism, benefits and medication. Also, recent days, hair treatment with laser and hair mesotherapy will take part .
Before buying medicine for yourself getting help from a dermatologist will save you from needless expenses money and time.
This part contains the information about hair loss treatment with medicine rogaine, propecia, laser, cloning and hair mesotherapy