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. 
Testosterone, like many anabolic steroids, was classified as a controlled substance in 1991. Testosterone is administered parenterally in normal and delayed-release (depot) forms. In September 1995, the FDA approved testosterone transdermal patches (Androderm), and many transdermal forms and brands are now available including implants, gels, and topical solutions. A testosterone buccal system, Striant, was FDA-approved in July 2003; Striant is a mucoadhesive product that adheres to the buccal mucosa and provides a controlled and sustained release of testosterone. In May 2014, the FDA approved an intranasal gel formulation of testosterone (Natesto). A transdermal patch (Intrinsa) for hormone replacement in women is under investigation; the daily dosages used in women are much lower than for products used in males. The FDA refused approval for Intrinsa in 2004 stating that more data regarding safety, especially in relation to cardiovascular and breast health, were required.
After the 1 st intramuscular injection of 1000 mg testosterone undecanoate to hypogonadal men, mean Cmax values of 38 nmol/L (11 ng/mL) were obtained after 7 days. The second dose was administered 6 weeks after the 1 st injection and maximum testosterone concentrations of about 50 nmol/L (15 ng/mL) were reached. A constant dosing interval of 10 weeks was maintained during the following 3 administrations and steady-state conditions were achieved between the 3 rd and the 5 th administration. Mean Cmax and Cmin values of testosterone at steady-state were about 37 (11 ng/mL) and 16 nmol/L (5 ng/mL), respectively. The median intra- and inter-individual variability (coefficient of variation, %) of Cmin values was 22 % (range: 9-28%) and 34% (range: 25-48%), respectively.