Testosterone is a naturally occurring sex hormone that is 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 or growth. It is only recommended for males with a known medical condition, such as a genetic disorder, problem with certain brain structures (called the hypothalamus and pituitary) or previous chemotherapy.

Testosterone injection is also used in women to treat certain types of breast cancer that have spread to other parts of the body.

Testosterone should not be used to enhance athletic performance or to treat normal male aging.

Testosterone injection is also used "off-label" for the treatment of gender dysphoria. Injections are typically administered weekly by the user in a home setting.

Do not use this medicine if you are pregnant or may become pregnant.

You should not receive testosterone if you have prostate cancer, male breast cancer, a serious heart condition, or severe liver or kidney disease.

Misuse of testosterone can cause dangerous or irreversible effects. Testosterone injections should be given only by a healthcare professional. Testosterone can lead to serious problems with the heart, brain, liver, endocrine, and mental health systems. Stopping testosterone may also lead to unpleasant withdrawal symptoms.

Testosterone injections have also been linked to a condition called pulmonary oil microembolism (POME), or a blood clot in the lung that can be fatal. Seek medical help immediately for symptoms including chest pain, dizziness, trouble breathing, urge to cough, throat tightening and fainting.

Testosterone is injected into a muscle. The injection is usually given every 2 to 4 weeks.

Testosterone injections should be given only by a healthcare professional. Misuse can lead to serious side effects or death.

The length of treatment will depend on the condition being treated.

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

While receiving this medicine, you will need frequent blood tests.

Testosterone can affect bone growth in boys who are treated for delayed puberty. Bone development may need to be checked with x-rays every 6 months during treatment.

You should not receive testosterone if you are allergic to it, or if you have:

• prostate cancer;

• male breast cancer;

• a serious heart condition;

• severe liver disease;

• severe kidney disease; or

• if you are pregnant or may become pregnant.

To make sure testosterone is safe for you, tell your doctor if you have:

• heart disease or coronary artery disease;

• a history of heart attack, stroke, or blood clot;

• diabetes;

• enlarged prostate;

• high cholesterol or triglycerides (a type of fat in the blood);

• breast cancer (in men, or in women who have hypercalcemia);

• liver or kidney disease;

• high calcium levels;

• if you are bedridden or otherwise debilitated; or

• if you take a blood thinner (warfarin, Coumadin, Jantoven).

This medicine can harm an unborn baby. Do not use testosterone if you are pregnant or may become pregnant. Tell your doctor right away if you become pregnant during treatment. Use effective birth control while you are receiving this medicine.

It is not known whether testosterone passes into breast milk or if it could harm a nursing baby. You should not breastfeed while using this medicine.

Call your doctor for instructions if you miss an appointment for your testosterone injection.

Since this medication is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

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

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

Get emergency medical help if you have any signs of a blood clot in the lung after using testosterone. These symptoms include chest pain, dizziness, trouble breathing, urge to cough, throat tightening and fainting.

Misuse of testosterone can cause dangerous or irreversible effects, such as enlarged breasts, small testicles, infertility, high blood pressure, heart attack, stroke, liver disease, bone growth problems, addiction, and mental effects such as aggression and violence.

Call your doctor at once if you have:

• chest pain or pressure, pain spreading to your jaw or shoulder;
• swelling in your ankles or feet, rapid weight gain;
• chest pain, sudden cough, wheezing, rapid breathing, coughing up blood;
• pain, swelling, warmth, or redness in one or both legs;
• nausea or vomiting;
• changes in skin color;
• increased or ongoing erection of the penis;
• impotence, ejaculation problems, decreased amounts of semen, decrease in testicle size;
• painful or difficult urination;
• shortness of breath (even with mild exertion);
• stomach pain, constipation, increased thirst or urination, muscle pain or weakness, joint pain, confusion, and feeling tired or restless; or
• upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

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 menstrual periods;

• male-pattern hair growth (such as on the chin or chest);

• hoarse or deepened voice; or

• enlarged clitoris.

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

• breast swelling;

• headache, anxiety;

• increased facial or body hair growth, male-pattern baldness;

• increased or decreased interest in sex;

• numbness or tingly feeling; or

• pain or swelling 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.

Certain drugs may interact with testosterone, including;

• Blood thinners (including warfarin, Coumadin, Jantoven)
• Anti-inflammatory drugs, such as oxyphenbutazone

Other prescription and over-the-counter medicines, vitamins, and herbal products may also react with testosterone. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.