Health Library

Tamoxifen (By mouth)

Tamoxifen (ta-MOX-i-fen)

Treats breast cancer. May prevent breast cancer in women who have a high risk.

Brand Name(s):

Nolvadex, Soltamox

When This Medicine Should Not Be Used:

How to Use This Medicine:

Liquid, Tablet

• Your doctor will tell you how much medicine to use. Do not use more than directed. Take this medicine at the same time each day.
• Swallow the tablet whole. Do not break, divide, chew, or crush it.
• Oral liquid: Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.
• This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.
• Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not store in the refrigerator or freezer. Throw away any unused medicine after 3 months of first opening the bottle.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Do not use this medicine together with blood thinners (including warfarin).
• Some medicines can affect how tamoxifen works. Tell your doctor if you are using aminoglutethimide, anastrozole, bromocriptine, letrozole, paroxetine, rifampin, or other cancer medicines.

Warnings While Using This Medicine:

• It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant. Birth control pills may not work as well to prevent pregnancy when used with this medicine. Use another form of birth control (including condoms or spermicide) along with your pills during treatment with this medicine and for 2 months after the last dose.
• Do not breastfeed during treatment with this medicine and for 3 months after the last dose.
• Medicines used to treat cancer are very strong and can have many side effects. Before receiving this medicine, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.
• Tell your doctor if you have liver disease, eye or vision problems (including cataracts), high cholesterol (fat) in the blood, or a history of stroke.
• This medicine may cause the following problems:
  • Increased risk for other cancers, including endometrium, liver, or uterus cancer
  • Blood clots
  • Eye or vision problems
• This medicine may make you bleed, bruise, or get infections more easily. Take precautions to prevent illness and injury. Wash your hands often.
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments. It is also important for women to have regular gynecologic check-ups while using this medicine.
• Make sure any doctor or dentist who treats you knows that you are using this medicine.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Blurred vision or other change in vision
• Chest pain, trouble breathing, coughing up blood
• Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
• Fever, chills, cough, sore throat, body aches
• Heavy or abnormal vaginal bleeding, pelvic pain or pressure, vaginal discharge
• New breast lumps
• Numbness or weakness in your arm or leg, or on one side of your body
• Pain in your lower leg (calf)
• Sudden or severe headache, problems with vision, speech, or walking
• Swelling in your hands, ankles, or feet
• Unusual bleeding, bruising, or weakness

If you notice these less serious side effects, talk with your doctor:

• Back or bone pain
• Constipation, diarrhea, stomach pain or upset
• Feeling of warmth, redness of the skin
• Headache, dizziness
• Loss of interest in sex or trouble having sex (in men)
• Weight gain

If you notice other side effects that you think are caused by this medicine, tell your doctor

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

Last Updated: 9/6/2024