Tamoxifen has rarely caused very serious (possibly fatal) strokes, blood clots in the lungs/legs, and cancer of the uterus. If you are taking tamoxifen to reduce the risk of breast cancer, or if your cancer is limited to the milk ducts (ductal carcinoma in situ-DCIS), then discuss the benefits and risks of taking this medication with your doctor. However, if you are taking tamoxifen to treat breast cancer, then the benefits of taking tamoxifen are greater than the risks of side effects.
Seek immediate medical attention if you develop symptoms of a stroke or blood clots in the lungs/legs, such as weakness on one side of the body, slurred speech, sudden vision changes, confusion, shortness of breath, chest pain, or calf pain/swelling.
Tell your doctor right away if you develop symptoms of cancer of the uterus, such as unusual changes in your monthly period (e.g., amount or timing of bleeding), unusual vaginal discharge, or pain/pressure below your "belly button" (navel).Who should not take tamoxifen?
Tamoxifen is used to treat breast cancer that has spread to other parts of the body (metastatic breast cancer), to treat breast cancer in certain patients after surgery and radiation therapy, and to reduce the chances of breast cancer in high-risk patients.
This medication can block the growth of breast cancer. It works by interfering with the effects of estrogen in the breast tissue.
Read the Medication Guide provided by your pharmacist before you start using tamoxifen and each time you get a refill. If you have any questions, consult your doctor or pharmacist.
Take this medication by mouth with or without food, usually once or twice daily for 5 years, or as directed by your doctor. Daily dosages greater than 20 milligrams are usually divided in half and taken twice a day, in the morning and evening, or as directed by your doctor. If you are using the liquid, measure the dose carefully using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.
Dosage is based on your medical condition and response to therapy.
Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day.
If you have breast cancer that has spread to other parts of the body, you may experience increased bone/cancer pain and/or disease flare-up as you start taking tamoxifen. In some cases, this may be a sign of a good response to the medication. Symptoms include increased bone pain, increased tumor size, or even new tumors. These symptoms usually disappear quickly. In any case, report these symptoms right away to your doctor.
Since this drug can be absorbed through the skin and lungs, women who are pregnant or who may become pregnant should not handle this medication or breathe the dust from the tablets. (See also Precautions section.)
Inform your doctor right away if your condition worsens (e.g., you get new breast lumps).
See also Warning section.
Hot flashes, nausea, leg cramps, muscle aches, hair thinning, headache, and numb/tingling skin may occur. A loss of sexual ability/interest may occur in men. If these effects persist or worsen, notify your doctor promptly.
Remember that your doctor has prescribed this medication because he or she 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 any of these unlikely but serious side effects occur: vision changes (e.g., blurred vision), eye pain, easy bruising/bleeding, mental/mood changes, swelling of ankles/feet, unusual tiredness.
Tell your doctor right away if any of these rare but very serious side effects occur: stomach/abdominal pain, persistent nausea/vomiting, dark urine, yellowing eyes/skin, signs of infection (e.g., fever, persistent sore throat).
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention 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 taking tamoxifen, 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.
If you have cancer limited to the milk ducts, or if you are taking this medication to prevent breast cancer, then this medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: a history of blood clots (e.g., deep vein thrombosis, pulmonary embolism, stroke), conditions that require treatment with a "blood thinner" (such as warfarin).
If you have breast cancer and a history of blood clots/stroke, you may or may not be able to take tamoxifen. Discuss the risks and benefits with your doctor.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: high cholesterol/triglycerides, limited or no ability to walk (immobility), diabetes, high blood pressure, smoking, cataracts, liver disease.
Before having surgery (especially breast reconstruction), tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
This medication is not recommended for use during pregnancy. It may harm an unborn baby. Women of childbearing age should start tamoxifen during their periods or get a negative pregnancy test before starting the medication. It is important to prevent pregnancy while taking this medication and for 2 months after treatment. Women must use reliable non-hormonal forms of birth control (such as condoms, diaphragms with spermicide) while taking this medication and for 2 months after stopping the medication.
It is not known if this medication passes into breast milk. Because of the potential risk to the infant, breast-feeding is not recommended while using this drug. Consult your doctor before breast-feeding.
Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.
This drug should not be used with the following medications because very serious interactions may occur: anastrozole, letrozole.
If you are currently using any of these medications listed above, tell your doctor or pharmacist before starting tamoxifen.
Tell your doctor or pharmacist of all prescription and nonprescription drugs you may use, especially of: "blood thinners" (e.g., warfarin), estrogens, hormonal forms of birth control (e.g., birth control pills, patches, implants), phenobarbital, rifamycins (e.g., rifampin), St John's wort.
Other medications can affect the removal of tamoxifen from your body, which may affect how tamoxifen works. Examples include cimetidine, SSRI antidepressants such as fluoxetine/paroxetine, among others.
This medication may interfere with certain laboratory tests (including thyroid tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.
This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.
If overdose is suspected, contact a poison control center or emergency room right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: shaking, unsteady walking, fainting, irregular heartbeat.
Laboratory and/or medical tests (e.g., blood counts, liver function tests, pelvic exams, mammogram, eye exams) should be performed periodically to monitor your progress or check for side effects. 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 and resume your usual dosing schedule. Do not double the dose to catch up.
Store at room temperature away from light and moisture. Do not store in the bathroom.
If you are using the liquid, do not refrigerate or freeze it. After you open the bottle, discard any unused liquid after 3 months.
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 for more details about how to safely discard your product.
Information last revised October 2015. Copyright(c) 2015 First Databank, Inc.
With WebMD's Medicine Cabinet, you can check interactions with drugs.Go to medicine cabinet