Testosterone has been subject to abuse, typically at doses higher than recommended for approved indication and in combination with other anabolic androgenic steroids; anabolic androgenic steroid abuse can lead to serious cardiovascular and psychiatric adverse reactions; if testosterone abuse suspected, check serum testosterone concentrations to ensure they are within therapeutic range; consider possibility of testosterone and anabolic androgenic steroid abuse in suspected patients who present with serious cardiovascular or psychiatric adverse events
Injectable steroids are injected into muscle tissue, not into the veins. They are slowly released from the muscles into the rest of the body, and may be detectable for months after last use. Injectable steroids can be oil-based or water-based. Injectable anabolic steroids which are oil-based have longer half-life than water-based steroids. Both steroid types have much longer half-lives than oral anabolic steroids. And this is proving to be a drawback for injectables as they have high probability of being detected in drug screening since their clearance times tend to be longer than orals. Athletes resolve this problem by using injectable testosterone early in the cycle then switch to orals when approaching the end of the cycle and drug testing is imminent.
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.