You should be aware that Proviron is also an estrogen antagonist which prevents the aromatization of steroids. Unlike the antiestrogen Nolvadex which only blocks the estrogen receptors (see Nolvadex) Proviron already prevents the aromatizing of steroids. Therefore gynecomastia and increased water retention are successfully blocked. Since Proviron strongly suppresses the forming of estrogens no rebound effect occurs after discontinuation of use of the compound as is the case with, for example, Nolvadex where an aromatization of the steroids is not prevented.
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 .