Testosterone is a naturally occurring sex hormone produced in a man's testicles. Small amounts of testosterone are also produced in a woman's ovaries and adrenal system.

Testosterone injection is used in men and boys to treat conditions caused by a lack of this hormone, such as delayed puberty, impotence, or other hormonal imbalances. Testosterone injection is not for use in treating low testosterone without certain medical conditions or due to getting older.

Testosterone enanthate is used in women to treat breast cancer that has spread to other parts of the body (metastatic) and cannot be treated with surgery.

Testosterone will not enhance athletic performance and should not be used for that purpose.

Testosterone injection may also be used for purposes not listed in this medication guide.

You should not be treated with this medicine if you are allergic to testosterone, or if you have:

• male breast cancer;
• prostate cancer;
• serious heart problems;
• severe liver disease;
• severe kidney disease; or
• an allergy to castor oil or sesame oil.

Testosterone injection is not for use in women who are pregnant. This medicine can harm an unborn baby.

Tell your doctor if you have ever had:

• high blood pressure;
• heart problems, coronary artery disease (clogged arteries);
• a heart attack or stroke;
• sleep apnea;
• an enlarged prostate and urination problems;
• high cholesterol or triglycerides;
• cancer;
• depression, anxiety, a mood disorder, suicidal thoughts or actions;
• diabetes;
• high red blood cell (RBC) counts; or
• liver or kidney disease.

Using testosterone may increase your risk of developing prostate cancer, liver problems, or heart problems (including heart attack, stroke, or death). Ask your doctor about these risks.

Women using testosterone should not breastfeed.

Testosterone should not be given to a child younger than 12 years old. Some types of this medicine are not approved for use by anyone younger than 18 years old.

Use Virilon IM (Intramuscular) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Tell your caregivers right away if you have a tight feeling in your throat, a sudden urge to cough, or if you feel light-headed or short of breath during or shortly after receiving the injection.

You will be watched closely for at least 30 minutes to make sure you do not have a reaction to the injection.

Call your doctor at once if you have:

• chest pain or pressure, pain spreading to your jaw or shoulder;
• shortness of breath, breathing problems at night (sleep apnea);
• swelling in your ankles or feet, rapid weight gain;
• a seizure;
• unusual changes in mood or behavior;
• increased or ongoing erection of the penis, ejaculation problems, decreased amounts of semen, decrease in testicle size;
• painful or difficult urination, increased urination at night, loss of bladder control;
• high levels of calcium in the blood--stomach pain, constipation, increased thirst or urination, muscle pain or weakness, joint pain, confusion, and feeling tired or restless; or
• high potassium level--nausea, weakness, tingly feeling, chest pain, irregular heartbeats, loss of movement;
• liver problems--right-sided upper stomach pain, vomiting, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes).
• signs of a blood clot deep in the body--swelling, warmth, or redness in an arm or leg;
• signs of a blood clot in the lung--chest pain, sudden cough, wheezing, rapid breathing, coughing up blood; or
• signs of a stroke--sudden numbness or weakness (especially on one side of the body), severe headache, slurred speech, balance problems.

Women receiving testosterone may develop male characteristics, which could be irreversible if treatment is continued. Call your doctor at once if you notice any of these signs of excess testosterone:

• acne;
• changes in your menstrual periods (including missed periods);
• male-pattern hair growth (such as on the chin or chest);
• hoarse or deepened voice; or
• enlarged clitoris.

Your testosterone injections may be delayed or permanently discontinued if you have certain side effects.

Common side effects (in men or women) may include:

• breast swelling;
• acne, increased facial or body hair growth, male-pattern baldness;
• increased or decreased interest in sex;
• headache, anxiety, depressed mood;
• increased blood pressure;
• numbness or tingly feeling;
• abnormal liver function tests;
• high red blood cell counts (hematocrit or hemoglobin);
• increased PSA (prostate-specific antigen); or
• pain, bruising, bleeding, redness, or a hard lump where the medicine was injected.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.