What is the cycle of hair growth?

Hair starts to grow early in life and, at first, each hair is quite thick, growing from a series of roots over the scalp. Each hair grows for between two and six years, producing about 1 inch every two months. It then rests for a short period and falls out. A new hair grows from the same root. Each new hair is slightly thinner than the last. Thus, everyone’s hair slowly thins and recedes as they age. This is an unstoppable process.

What is male pattern baldness?

This affects younger men and, if not treated, produces a clear M pattern on the head as the hair slowly recedes at the temples from the hairline. The crown also thins prematurely and can produce a bald spot. Over time, the areas of baldness can join up to form a U shape. Other hair loss has different causes and will not respond to treatment using propecia.

What causes male pattern baldness?

The precise cause is not understood. Researchers suspect a combination of factors. There is some evidence suggesting that there may be a genetic link. Baldness does run in some families. There is also emerging evidence that an excess of male hormone may be a contributing factor. This latter cause is addressed by propecia which slows the conversion of testosterone into dihydrotestosterone.

What does the evidence from clinical trials show?

There is clear evidence that the use of propecia is effective to slow hair loss and, in some cases, to encourage regrowth. The three major trials have involved almost four thousand men in the early stages of hair loss. Some of the participants have been monitored for up to five years. There is a slight racial element in that the drug appears to be more effective among the caucasian population than among other racial groups. Almost 90% of caucasian men see an improvement in their appearance, whereas other groups have slightly lower percentages. The evidence from the trials was collected in two forms: through physically counting hairs on designated parts of the head, and self-assessment by the participants who are given photographs taken from fixed camera positions. As against the placebo, significant areas of regrowth were demonstrated in the period from six to twelve months. Thereafter, the hair counts were stable. But, if propecia is discontinued, hair loss resumes. Resuming the use of propecia is then significantly less effective. The conclusion of the research is therefore that men benefit from propecia if they start using it early and, once they have started, they must continue its use to maintain their appearance.