Bioidentical hormones have the same chemical structure as hormones produced in the human body. There have been many studies demonstrating their safety. At this time, with the ready availability of bioidentical hormones, there is no reason to use non-human formulations. There is a track record of benefit and safety for women taking controlled doses of these hormones, in carefully selected formulations, under medical supervision. Horse hormones and progestins for hormone replacement should become obsolete. Patient demand will make this happen.
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).