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.
The manufacturers of certain testosterone products (., AndroGel and Striant) state that their products are contraindicated in patients with soybean, soy, or soya lecithin hypersensitivity because they are derived partially from soy plants. There is a risk of serious hypersensitivity reactions or anaphylaxis with the use of testosterone undecanoate (Aveed) oil for injection. These allergic reactions can occur after any injection of testosterone undecanoate during the course of therapy, including after the first dose. Observe patients in the healthcare setting for 30 minutes after an Aveed injection in order to provide appropriate medical treatment in the event of serious hypersensitivity reactions or anaphylaxis. The Aveed injection contains benzyl benzoate, the ester of benzyl alcohol and benzoic acid, and refined castor oil. Therefore, testosterone undecanoate use is contraindicated in patients with polyoxyethylated castor oil hypersensitivity, benzoic acid hypersensitivity, or benzyl alcohol hypersensitivity. Patients with suspected hypersensitivity reactions should not be re-treated with testosterone undecanoate injection.