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 . 
Athletes, like all others, may have illnesses or conditions that require them to take particular medications. If the medication an athlete is required to take to treat an illness or condition happens to fall under the prohibited list, a therapeutic use exemption may give that athlete the authorization to take the needed medicine. Criteria for granting a therapeutic use exemption are 1.) The athlete would experience significant health problems without taking the prohibited substance or method, 2.) The therapeutic use of the substance would not produce significant enhancement of performance, and 3.) There is no reasonable therapeutic alternative to the use of the otherwise prohibited substance or method. Note hormone replacement therapy (HRT), . supplementing with prescribed testosterone in any form to raise testosterone levels due to natural decreases that occur with aging (even if to just elevate levels to within ‘normal’ ranges), is NOT considered a medicinal exception. Persons using HRT would not be eligible for WPA/NANBF/IPE competition.