This should go without saying. If you were thinking of asking this question, take it from me, you are not ready to start using steroids. After a cycle of steroids your natural sex hormone levels will be severely suppressed due to a mechanism called negative feedback. To preserve gains and keep a mentally and physically healthy life-style, you need to get your testosterone levels back on line. When a deficit of steroids in the body has occured, it will attempt to make natural testosterone again. But unfortunately steroid levels do not drop off, usually there is an estrogen rebound which prolongs the negative feedback. Estrogen of course will not suffice to keep your gains. So the need of an estrogen antagonist is needed post-cycle, either Clomid (clomiphene citrate) or Nolvadex (tamoxifen citrate).

During longer or very suppressive cycles (Deca, long term test, trenbolone) your testicles may begin to shrink heavily due to disuse. this may make it harder to make natural test right off the bat. In such cases it is advised you use HCG as well to bring back the size of the testicles first.