Testosterone Undecanoate


TESTOSTERONE is the main male hormone. It supports normal male development such as muscle growth, facial hair, and deep voice. It is used in males to treat low testosterone levels. Compare androgens.

Testosterone Undecanoate Side Effects

What should I watch for?

Visit your doctor or health care professional for regular checks on your progress. They will need to check the level of testosterone in your blood.

This medicine is only approved for use in men who have low levels of testosterone related to certain medical conditions. Heart attacks and strokes have been reported with the use of this medicine. Notify your doctor or health care professional and seek emergency treatment if you develop breathing problems; changes in vision; confusion; chest pain or chest tightness; sudden arm pain; severe, sudden headache; trouble speaking or understanding; sudden numbness or weakness of the face, arm or leg; loss of balance or coordination. Talk to your doctor about the risks and benefits of this medicine.

This medicine may affect blood sugar levels. If you have diabetes, check with your doctor or health care professional before you change your diet or the dose of your diabetic medicine.

Testosterone injections are not commonly used in women. Women should inform their doctor if they wish to become pregnant or think they might be pregnant. There is a potential for serious side effects to an unborn child. Talk to your health care professional or pharmacist for more information. Talk with your doctor or health care professional about your birth control options while taking this medicine.

This drug is banned from use in athletes by most athletic organizations.


Common and Rare Side Effects

Discuss these possible effects with your doctor:

Tumors of the liver, liver cancer, or peliosis hepatis (a form of liver disease) have occurred during long-term, high-dose therapy with androgens. Although these effects are rare, they can be very serious and may cause death.

Androgens can stimulate existing prostate cancer in men who already have it but have not yet been diagnosed. Also, the prostate (a male gland) may become enlarged. Enlargement of the prostate does not mean that cancer will develop. If enlargement occurs and you have difficulty in urinating, it is a good idea to be checked by your doctor.

When androgens are used in women, especially in high doses, male-like changes may occur, such as hoarseness or deepening of the voice, unnatural hair growth, or unusual hair loss. Most of these changes will go away if the medicine is stopped as soon as the changes are noticed. However, some changes, such as voice changes or enlarged clitoris, may not go away.

When androgens are used in high doses in males, they interfere with the production of sperm. This effect is usually temporary and only happens during the time you are taking the medicine. However, discuss this possible effect with your doctor if you are planning on having children.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

For females only

Acne or oily skin

decreased breast size

irregular menstrual cycles

hoarseness or deepening of voice

increase in size of female genitals

increase in unnatural hair growth or male pattern baldness

These symptoms may occur in females whose male sexual partner uses a scrotal patch.

For males only

Blistering of skin under patch (especially when the nonscrotal patch is applied to bony areas of the skin)

breast soreness or enlargement

frequent or continuing erection of penis lasting up to 4 hours or painful penile erections lasting longer than 4 hours

frequent urge to urinate

itching or redness of skin under patch (less likely with nonscrotal patch) or at site of implants, mild to severe

For prepubertal boys only


early growth of pubic hair

enlargement of penis

frequent or continuing erections

Less common

For males or females


frequent or continuing headache

lack or loss of strength


overall body flushing, redness, or itching of skin

rapidly changing moods, such as depersonalization, dysphoria, euphoria, depression, paranoia, and quick to react or overreact emotionally

swelling of feet or lower legs

unusual bleeding

unusual tiredness

yellow skin or eyes (occurring with fluoxymesterone or methyltestosterone more often than with testosterone)

For females with breast cancer or bedridden males or females—in addition to the side effects listed above

Confusion or mental depression


increased thirst

increased urge to urinate or increased amount of urine

For males only

Black, tarry stools

burning sensation or hardening or thickening of skin under patch


continuing pain at site of implants

difficulty in urinating

itching, skin redness, or rash under patch, severe (less likely with nonscrotal patch)

pain in scrotum or groin

vomiting of blood or material that looks like coffee grounds


For males or females—more likely with oral androgens or long-term or high doses of androgens

Abdominal or stomach pain, continuing

bad breath odor, continuing

black, tarry or light-colored stools or dark urine



loss of appetite, continuing

mood or mental changes

purple or red spots on body or inside the mouth or nose

sore throat

swelling, pain, or tenderness of abdomen

vomiting of blood

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

For males and females

Acne, mild

decrease or increase in sexual desire or drive


hair loss or thinning of hair

increase in pubic hair growth

infection, pain, redness, or other irritation at site of injection


stomach pain

trouble in sleeping

For males only

Decrease in testicle size

infection, pain, redness, swelling, sores, or other skin irritation underneath patch

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

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