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 . 
Trenbolone is often touted as an anabolic steroid that has ‘harsh’ side effects and tends to frighten many individuals who are considering the use of this compound. First and foremost, it should be established that because Tren does not aromatize into Estrogen at any dosage, there is no risk for encountering Estrogenic side effects . The Trenbolone side effects of particular concern are its androgenic side effects, and other side effects that are not usually seen with any other anabolic steroids (such as insomnia, excessive sweating, etc.).