Q: I am a 21 yrs old male having serious hair loss over the last few years. I also have very little facial hair. Since Propecia is a DHT blocker can it inhibit beard growth? — E.M., Astoria, N.Y.

A: As you suggest, it would be reasonable to assume that since DHT stimulates beard growth, blocking DHT (with finasteride) would tend to inhibit its growth. In practice, this does not seem to be the case, i.e. we don’t find that Propecia has any effect on facial hair. The reason is not clear.

It is interesting to note that testosterone stimulates growth of axillary and pubic hair, but not scalp hair. Scalp hair growth is not androgen dependent, only scalp hair loss is.

DHT stimulates terminal hair growth of the beard, trunk and limbs, external ears and nostrils. Of course, it also is responsible for the bitemporal reshaping of hairline as one passes into adulthood and causes male patterned baldness (androgenetic alopecia).