Aveed (testosterone undecanoate) is an injectable form of testosterone used in men for testosterone replacement therapy. This medication is injected into a muscle every 10 to 14 weeks. Each 10 mL vial of Aveed contains 250 mg/mL of testosterone undecanoate, a long-acting form of testosterone. The testosterone undecanoate in Aveed is produced in a castor-oil-based solvent, which is slowly absorbed in the body after injection. Aveed is used to treat hypogonadism in men and gender dysphoria in transgender men. This medication may also be used off-label to increase muscle mass and strength in athletes and bodybuilders.