These side effects went away in all men who discontinued therapy because of them and also disappeared in 58 percent of men who chose to continue taking Propecia. The BBC reported in January that Propecia works by blocking the way the body gets rid of the sex hormone, testosterone. By making the hormone stay in the body longer, Propecia prevented further hair loss, and the possibility of the growth of new hair. The New Zealand Propecia Website explains that male pattern baldness is actually caused by changes in the way that your hairs grow. The hairs become smaller, finer and light in color, so much so that they eventually can't be seen.
Hair roots receive nutrients from blood vessels, which contain testosterone.
It is the DHT hormone that causes the damage to the hair. Propecia works by reducing DHT, in the scalp thereby allowing hairs to revert to a normal growth cycle. Propecia works only on male pattern baldness and does not work on women who are losing their hair. Women must not use Propecia when they are or may potentially be pregnant because it may cause abnormalities of the male baby's sex organs, a condition known as hypospadias. In addition, women should not handle crushed or broken tablets when they are pregnant or may potentially be pregnant.