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.
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 . 
Testosterone is considered an essential absolute base to any cycle due to the fact that Testosterone is the body’s natural anabolic androgen. It also serves as an all-round excellent mass building compound that is suitable for bulking and strength gaining, and can also be utilized for the purpose of cutting and fat loss as well. In order to carry results further, other bodybuilding steroids are combined with (or “stacked” with) Testosterone. Some of the most popular anabolic steroids in this regard are compounds such as Dianabol (Methandrostenolone) , Winstrol (Stanozolol) , Nandrolone (Deca-Durabolin), and Trenbolone , among a few others. These Dianabol and Winstrol are two examples of oral bodybuilding steroids, though Winstrol does also come in an injectable format that is chemically identical to the oral, and thus even the injectable Winstrol can be ingested orally in order to garner the same effects as the tablet format. Oral anabolic steroids are generally regarded as bodybuilding steroids that are supplementary adjuncts to a solid base anabolic steroid cycle involving injectable bodybuilding steroids (namely, Testosterone).