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 .  The infamous "duchess" cocktail administered to Russian athletes at the Sochi Winter Olympics consisted of oxandrolone , a metenolone ester, and a trenbolone ester. 
Normally taken orally but some non-EU or US countries produce injectable versions. Its ability to increase muscle mass, harden the body and increase stamina has made it one of the go-to steroid choices for many a user – and it’s the one they use on racehorses to make them go faster. But many users report acne flare-ups and dry joints, and while it’s easy on the hairline, it’s hard on the liver. Warning signs of liver problems include abdominal pain, light-coloured stools, dark-coloured urine, unusual fatigue, nausea and yellowing of the skin or eyes. Brand names include Winstrol.