The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine . 
WARNING: This medicine can have very serious side effects and has been misused and abused. Do not use with other medicines that slow your breathing or mental activity, or cause sleepiness. XYREM has caused changes in alertness (or consciousness) and trouble breathing (respiratory depression). Call your doctor right away if you have any of these serious side effects. These effects happened even when XYREM was given in recommended doses. In studies, almost all of the patients with narcolepsy who were given XYREM were also taking medicines to help them stay awake during the day. XYREM is a form of gamma hydroxybutyrate (GHB). Abuse of GHB alone or with other drugs that cause changes in alertness (or consciousness) has caused serious side effects. These effects include seizures, trouble breathing (respiratory depression), very low levels of alertness (or consciousness), coma, and death.