Finasteride belongs to a group of medicines called Type II ‘5-alpha reductase inhibitors’. Finasteride is used for the treatment of male pattern hair loss (also known as androgenetic alopecia). Finasteride increases hair growth on the scalp and prevents further hair loss in men. Men with mild to moderate, but not complete hair loss, can benefit from using Finasteride. How does the hair on your head grow? On average your hair grows about 1 centimetre (half an inch) each month. Hair grows from hair follicles, which are located under your skin. A single scalp hair grows continuously for 2-4 years (growth phase) and then stops growing for 2-4 months (rest phase). After this the hair falls out. In its place a new healthy hair begins to grow, and the cycle is repeated. The hairs on your scalp are always in different stages of this cycle so it is normal to lose scalp hair every day. What is male pattern hair loss? Male pattern hair loss is a common condition in which men experience thinning of the hair on the scalp, often resulting in a receding hairline and/or balding on the top of the head. This condition is thought to be caused by a combination of genetic factors and a particular hormone, DHT (dihydrotestosterone). DHT causes a decrease in the growth phase and thinning of the hair (see picture). This leads to male pattern hair loss. These changes can start to occur in some men in their 20s and become more common with age. Once hair loss has occurred over a long period of time, the hair may be permanently lost. How does Finasteride work? Hair grows in follicles that have a life span of around 3 years after which the hair falls out and new hair then grows in that follicle. The hair follicles of men affected by male pattern hair loss gradually become smaller. As a result the the new hair that grows in these follicles becomes thinner and sheds quicker eventually leading to balding. Male hormones cause these changes. Hair follicles convert the male hormone testosterone into another hormone called dihydrotestosterone (DHT). Hair follicles become more sensitive to dihydrotestosterone and this causes the hair follicles to shrink. Finasteride lowers the levels of DHT in the scalp. This helps to reverse the balding process, leading to an increased hair growth and prevention of further hair loss. Finasteride 1mg reduces the amount of testosterone converted to DHT which results in hair regrowth and hair thickness in most men. A recent 5 year clinical study showed that 90% of balding men either regrew hair or had no further hair loss whilst taking Finasteride (Propecia).