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 risk of hepatotoxicity and death associated with CPA treatment is reportedly the reason that CPA has not been approved by the FDA for use in the United States.  Patients being treated with high-dose CPA should be closely monitored with liver function tests .  The risk is dose-dependent, and the low doses of CPA used in birth control pills (2 mg) have been said to represent a non-significant risk.  However, a German woman who had been taking Diane-35 (containing 2 mg/day CPA) for contraception for 14 years died of liver cancer, and this led to a safety review by drug regulators and the eventual restriction of CPA throughout Europe for the indication of acne treatment in women. 
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