Avodart is Dutasteride, a 5 alpha reductase inhibitor used in the treatment of benign hypertrophy of prostate (enlargement of prostate). It is also used (off label) for male pattern baldness (alopecia) . It decreases prostate size & improves the urine flow by reducing testosterone levels. Decreased libido is a routine side effect as it reduces testosterone levels. Dutasteride stays in the body for a long time. It increases hair growth in scalp (head) but not in other body areas. the reason is, the level of testosterone in hair follicle in scalp is more than that found in body hair follicle. By blocking the synthesis (production) of testosterone, Dutasteride decreases the level of androgens, preventing the age related baldness. That is why there is no thinning of your scalp hair. But in some persons Dutasteride has been reported to reduce hair growth, primarily body hair. The amount of body hair reduces as age advances probably due to reduced blood circulation and Dutasteride does not increase the longevity of body hair. So, the reason for the thinning of body hair could be due to 1. Dutasteride resulting in more scalp hair, but no effect in body hair. 2. Dutasteride causing reduction of body hair, an uncommon side effect seen in very few individuals.