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. Methyltestosterone is similar to the natural testosterone produced by your body. It 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.

Methyltestosterone may also be used in certain adolescent boys to cause puberty in those with delayed puberty. It may also be used to treat certain types of breast cancer in women.

Take this medication by mouth with or without food as directed by your doctor, usually 1 to 4 times a day. The dosage is based on your medical condition, testosterone blood levels, and response to treatment.

Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same times each day.

Misuse or abuse of testosterone or testosterone-like products can cause serious side effects such as heart disease (including heart attack), stroke, liver disease, mental/mood problems, abnormal drug-seeking behavior, or improper bone growth (in adolescents). Do not increase your dose or use this drug more often or for longer than prescribed. When testosterone is misused or abused, you may have withdrawal symptoms (such as depression, irritability, tiredness) when you suddenly stop using the drug. These symptoms may last from weeks to months.

Tell your doctor if your condition does not get better or if it gets worse.

Nausea, vomiting, headache, skin color changes, increased/decreased sexual interest, oily skin, hair loss, and acne may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• mental/mood changes (such as anxiety, depression, increased anger)
• trouble sleeping/snoring
• signs of liver disease (such as nausea/vomiting that doesn't stop, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine)
• hands/ankles/feet swelling
• unusual tiredness
• fast/irregular heartbeat

Get medical help right away if you have any very serious side effects, including:

• shortness of breath/rapid breathing
• chest/jaw/left arm pain
• unusual sweating
• confusion
• sudden dizziness/fainting
• pain/swelling/warmth in the groin/calf
• sudden/severe headaches
• trouble speaking
• weakness on one side of the body
• sudden vision changes

If you are male, tell your doctor right away if you have any serious side effects, including:

• trouble urinating
• breast swelling/tenderness
• too frequent/prolonged erections

Rarely, males may have a painful or prolonged erection lasting 4 or more hours. If this occurs, stop using this drug and get medical help right away, or permanent problems could occur.

If you are female, tell your doctor right away if you have any serious side effects, including:

• deepening of the voice
• hoarseness
• unusual facial/body hair growth
• enlarged clitoris
• irregular menstrual periods

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before using methyltestosterone, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• cancer (such as breast cancer in men, prostate cancer)
• blood clots (such as in the leg, lungs)
• heart disease (such as heart failure, chest pain, heart attack)
• stroke
• liver problems
• kidney problems
• certain mineral imbalance (high calcium blood level)
• high cholesterol
• high blood pressure
• enlarged prostate
• breathing problems (such as sleep apnea, chronic obstructive pulmonary disease-COPD)
• diabetes

If you have diabetes, this product may lower your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of low blood sugar, such as sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, or tingling hands/feet. Your doctor may need to adjust your diabetes medication, exercise program, or diet.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the side effects of this drug, especially prostate/liver problems, swelling of arms/legs.

Children may be more sensitive to the side effects of this drug. In children, it may affect bone growth. Monitor your child's height periodically.

This medication can affect fertility in males. Ask your doctor for more details.

This medication must not be used during pregnancy. It may harm an unborn baby. Discuss the use of reliable forms of birth control (such as condoms, birth control pills) with your doctor. If you become pregnant or think you may be pregnant, tell your doctor right away.

It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• "blood thinners" (such as warfarin)

This medication may interfere with certain lab tests (such as thyroid function tests), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

Do not share this medication with others. Sharing it is against the law.

Lab and/or medical tests (such as blood testosterone levels, red blood cell counts, liver function, blood cholesterol levels, PSA test) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.