As Testosterone Propionate is, of course, Testosterone, it suffers from moderate aromatization which results in the Estrogenic side effects of bloating, water retention, elevated blood pressure (as a result of the bloating), and risks of gynecomastia. This soft and puffy look that bloating brings to the physique is generally undesirable for most users that wish to engage in cutting cycles or lean mass cycles. Therefore, Testosterone Propionate must be utilized with an aromatase inhibitor in order to disable the aromatase enzyme and eliminate the water retention effect of the Estrogen conversion, which should result in a harder looking physique without the soft puffiness. In doing so, Testosterone can successfully be utilized as a ‘hardening’ and cutting compound, as well as for lean mass gains. Some individuals prefer the water retention, convinced that it aids in protecting tissues and connective tissue from the stressors of heavy strength gains and heavy lifting, and therefore Testosterone is preferred as a bulking and strength gaining compound in this case. In any case, Testosterone is also an excellent compound for all-out bulking and strength gaining cycles, which is what its main use seems to be among bodybuilders and athletes. It is a very versatile compound that can provide the anabolic strength necessary for bulking phases.
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. 
Fluid and electrolyte disturbances: Retention of sodium, chloride, water, potassium, calcium, and inorganic phosphates.
Gastrointestinal: Nausea, cholestatic jaundice, alterations in liver function tests, rarely hepatocellular neoplasms and peliosis hepatis (see WARNINGS ).
Hematologic: Suppression of clotting factors II, V, VII, and X, bleeding in patients on concomitant anticoagulant therapy, and polycythemia.
Nervous system: Increased or decreased libido, headache, anxiety, depression, and generalized paresthesia.
Allergic: Hypersensitivity, including skin manifestations and anaphylactoid reactions.
Vascular Disorders: venous thromboembolism
Miscellaneous: Inflammation and pain at the site of intramuscular injection.