This medication is used in men who do not make enough of a natural substance called testosterone. In males, testosterone is responsible for many normal functions, including growth and development of the genitals, muscles, and bones. It also helps cause normal sexual development (puberty) in boys. Testosterone belongs to a class of drugs known as androgens. It works by affecting many body systems so that the body can develop and function normally.

The most common side effects of androgen therapy are:

* Skin and Appendages - Hirsutism, male pattern baldness, and acne.
* Fluid and Electrolyte Disturbances - Retention of sodium, chloride, water, potassium, calcium (see WARNINGS), and inorganic phosphates.
* Gastrointestinal- Nausea, cholestatic jaundice, alterations in liver function tests; rarely, hepatocellular neoplasms, peliosis hepatis.
* Hematologic - Suppression of clotting factors II, V, VII, and X; bleeding in patients on concomitant anticoagulant therapy; polycythemia.
* Nervous System - Increased or decreased libido, headache, anxiety, depression, and generalized paresthesia.
* Metabolic - Increased serum cholesterol.
* Miscellaneous - Rarely, anaphylactoid reactions; inflammation and pain at injection site.