As alluded to above, one very important thing to acknowledge when using AAS (whether taking one hormone, stacking or cycling) is the risk of harmful side effects. Within a steroid cycle, the users will often stack other non-anabolic hormones into their program to maximize specific cycle objectives for example: the addition of drugs like Clenbuterol and/or Cytomel /T3 augment cutting/definition cycles; others called aromatase inhibitors (estrogen reducing drugs) like Letrozole . Letro and Anastrozole Arimidex are often included to inhibit the conversion of excess testosterone to negatively cycle impacting estrogen and; incorporating post-cycle therapy (PCT) drugs such as the synthetic estrogens Tamoxifen . Nolvadex , or Clomiphene Citrate . Clomid (which act as anti-estrogens in the male body), can be used alone, together, or in conjunction with those like Mesterolone . Proviron and Human Chorionic Gonadotropin ( HCG ) during PCT to bridge the gap between the end of a steroid cycle (synthetic testosterone usage) and the restoration of the bodys natural testosterone production. These drugs too must be researched, and controlled in similar fashion to AAS. Thus, steroid cycles can be as simple or complex as the users individualized goals, cycle histories and levels of understanding. Below are three samples of AAS stacked cycles of varying complexity along with a beginning PCT sample, and an explanation of goal intention & rationale for the selected compounds, dosages & durations. These illustrations and commentaries will provide a better understanding of what stacking and cycling are along with the many nuances they require.
Some bodybuilders and athletes use trenbolone esters for their muscle-building and otherwise performance-enhancing effects.  Such use is illegal in the United States and many other countries. The DEA classifies trenbolone and its esters as Schedule III controlled substances under the Controlled Substances Act .  Trenbolone is classified as a Schedule 4 drug in Canada  and a class C drug with no penalty for personal use or possession in the United Kingdom .  Use or possession of steroids without a prescription is a crime in Australia .