Steroids will can only increase your muscle mass by making your current muscle cells bigger. AGrowth hormone (GH) is the only way you can actually get new cells, and that cannot be reversed: steroid gains are easily lost. Combining the two is fantastic. I went from 175 to 215 in 45 days... Your penis will never get smaller. You might having problems getting erections, but only if you intake the steroids in the wrong way. Every drug has a side effect, and luckily there's a drug to counter every of those side-effects, and so on and so on. (minimizing the side-effects along the way.) If you add testosterone (for example) to your system, your testes will stop naturally producing testosterone because of the normal levels in the system. There won't be any serious problems until you stop suplementing your hormones with testosterone. You testicules won't get a signal/trigger to start producing testosterone again. You have to start taking a drug called clomid (synthesized for prostate cancer patients) a week before getting off the "juice" in order for your natural levels to normalize before removing the outside source. Another reason you might lose your manhood is cause by your oestrogen levels approaching those of a woman. If you have too much testosterone in your system, your body will convert it to oestrogen ( not knowing what to do with the surplus, and both being so similar). OEstrogen makes you store fat and water around the hips and nipple line, makes you emotional (juice monkeys are known to break down and cry), and might actually give you enlarged mamaries (bitch-tits, or "gynecomastia", $6K surgery). Might also lower your sperm count in the process. You have to take a drug called Nolvadex to counter those effects ( oestrogen receptor blocker developed for women with breast cancer) The only way to take steroids safely is to embrace polypharmacy. You can't just take one drug. You have to sequentially layer them in both time and strength. sorry if I went off topic.