Dihydrotestosterone (DHT) (referred to as androstanolone or stanolone when used medically) can also be used in place of testosterone as an androgen. The availability of DHT is limited; it is not available in the United States or Canada, for instance, but it is available in certain European countries, including the United Kingdom , France , Spain , Belgium , Italy , and Luxembourg .  DHT is available in formulations including topical gel, buccal or sublingual tablets, and as esters in oil for intramuscular injection.  Relative to testosterone, and similarly to many synthetic AAS, DHT has the potential advantages of not being locally potentiated in so-called androgenic tissues that express 5α-reductase (as DHT is already 5α-reduced) and of not being aromatized into an estrogen (it is not a substrate for aromatase).
Male hormones decrease in production during the aging process in an event sometimes called male menopause , but there isn't clear evidence as to why this is. Some guess that it has to do with an increase in body fat which contains the enzyme aromatase . This enzyme has been indirectly linked with a decrease in male hormones in the body. Too little testosterone may cause a decrease in sexual interest as well as erectile dysfunction. Hormone levels can be tested to find out if they have decreased in effectiveness and hormone replacement therapy is possible for those who are effected by the problem.
Risks associated with HT include the following: