Common (1% to 10%): Sinusitis, nasopharyngitis, upper respiratory tract infection , bronchitis
Uncommon (% to 1%): Cough, dyspnea, snoring, dysphonia
Rare (less than %): Pulmonary microembolism (POME) (cough, dyspnea, malaise, hyperhidrosis, chest pain, dizziness, paresthesia, or syncope) caused by oily solutions
Frequency not reported: Sleep apnea
Postmarketing reports: Chest pain, asthma , chronic obstructive pulmonary disease , hyperventilation, obstructive airway disorder, pharyngeal edema, pharyngolaryngeal pain, pulmonary embolism , respiratory distress, rhinitis , sleep apnea syndrome [ Ref ]
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.