Taking HGH without a prescription is considered criminal by those unhealthy folks who do legislation in The United States.
HGH, like AAS (Anabolic Androgrenic Steroids) can cause a large number of positive effects on the body and promote wellness. That's why GH, and AAS, have long been used for the treatment of chronic disease, burns, and in particular any disease with folks that have compromised immune systems. I.e., these things are given to folks who are the sickest of the sick. As well, there is a reasonably strong movement for more use of these compounds in anti-aging, obesity control, depression control, and general wellness promotion. That's also why no federal agency, and nearly no trade agencies, have EVER recommended their control, and, in fact, have recommended against it.
I'd encourage you to visit any of the good bodybuilding boards where you'll find a long list of items to read and research, and I'd encourage you to google on anti-aging. Anti-aging is quickly becoming a therapy that folks are demanding because these compounds work, and work well, to promote a sense of well being, keep the sick from getting sicker (HIV, cancer and so on), and help athletes to attain a higher level of training.
As well, view HBO Real Sports Episode #99, and the movie "Bigger Stronger Faster"