A 2006 study determined that 1-testosterone has a high androgenic and anabolic potency even without being metabolized, so it can be characterized as a typical anabolic steroid. 1-Testosterone binds in a manner that is highly selective to the androgen receptor (AR) and has a high potency to stimulate AR-dependent transactivation . In vivo , an equimolar dose of 1-testosterone has the same potency to stimulate the growth of the prostate , the seminal vesicles and the androgen-sensitive levator ani muscle as the reference anabolic steroid testosterone propionate , but, unlike testosterone propionate, 1-testosterone also increases liver weight. 
The preservative benzyl alcohol has been associated with serious adverse events, including the "gasping syndrome", and death in pediatric patients. Although normal therapeutic doses of this product ordinarily deliver amounts of benzyl alcohol that are substantially lower than those reported in association with the "gasping syndrome", the minimum amount of benzyl alcohol at which toxicity may occur is not known. The risk of benzyl alcohol toxicity depends on the quantity administered and the liver and kidneys' capacity to detoxify the chemical. Premature and low-birth weight infants may be more likely to develop toxicity.
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.