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 effects of taking Trenbolone Enanthate may continue once the user has stopped taking the steroid. The drug suppresses the natural production of testosterone by the user as it alters the Hypothalamus-Pituitary-Testes-Axis (HPTA). This is the area which is responsible for production of the two gonadal hormones that trigger the production of testosterone in the testicles. The effect of Trenbolone Enanthate on the HPTA can be very severe. It may take some time for the Axis to recover and it could require medical advice and hormone treatment before the normal production of testosterone can begin again.
Side effects of testosterone enanthate include symptoms of masculinization like acne , increased hair growth , voice changes , and increased sexual desire .  The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT).   It has strong androgenic effects and moderate anabolic effects, which make it useful for producing masculinization and suitable for androgen replacement therapy .  Testosterone enanthate is a testosterone ester and a long-lasting prodrug of testosterone in the body.    Because of this, it is considered to be a natural and bioidentical form of testosterone.