Tamoxifen may cause cancer of the uterus (womb), strokes, and blood clots in the lungs. These conditions may be serious or fatal. Tell your doctor if you have ever had a blood clot in the lungs or legs, a stroke, or a heart attack. Also tell your doctor if you smoke, if you have high blood pressure or diabetes, if your ability to move around during your waking hours is limited, or if you are taking anticoagulants ('blood thinners') such as warfarin (Coumadin). If you experience any of the following symptoms during or after your treatment, call your doctor immediately: abnormal vaginal bleeding; irregular menstrual periods; changes in vaginal discharge, especially if the discharge becomes bloody, brown, or rusty; pain or pressure in the pelvis (the stomach area below the belly button); leg swelling or tenderness; chest pain; shortness of breath; coughing up blood; sudden weakness, tingling, or numbness in your face, arm, or leg, especially on one side of your body; sudden confusion; difficulty speaking or understanding; sudden difficulty seeing in one or both eyes; sudden difficulty walking; dizziness; loss of balance or coordination; or sudden severe headache.
Keep all appointments with your doctor. You will need to have gynecological examinations (examinations of the female organs) regularly to find early signs of cancer of the uterus.
If you are thinking about taking tamoxifen to reduce the chance that you will develop breast cancer, you should talk to your doctor about the risks and benefits of this treatment. You and your doctor will decide whether the possible benefit of tamoxifen treatment is worth the risks of taking the medication. If you need to take tamoxifen to treat breast cancer, the benefits of tamoxifen outweigh the risks.
Your doctor or pharmacist will give you the manufacturer's patient information sheet (Medication Guide) when you begin treatment with tamoxifen and each time you refill your prescription. Read the information carefully and ask your doctor or pharmacist if you have any questions. You can also visit the Food and Drug Administration (FDA) website ( Web Site) or the manufacturer's website to obtain the Medication Guide.
Tamoxifen is used to treat breast cancer that has spread to other parts of the body in men and women. It is used to treat early breast cancer in women who have already been treated with surgery, radiation, and/or chemotherapy. It is used to reduce the risk of developing a more serious type of breast cancer in women who have had ductal carcinoma in situ (DCIS; a type of breast cancer that does not spread outside of the milk duct where it forms) and who have been treated with surgery and radiation. It is used to reduce the risk of breast cancer in women who are at high risk for the disease due to their age, personal medical history, and family medical history.
Tamoxifen is in a class of medications known as antiestrogens. It blocks the activity of estrogen (a female hormone) in the breast. This may stop the growth of some breast tumors that need estrogen to grow.
Tamoxifen comes as a tablet to take by mouth. Tamoxifen is usually taken once or twice a day with or without food. Take tamoxifen at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain anything you do not understand. Take tamoxifen exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Swallow tamoxifen tablets whole; do not split, chew, or crush them. Swallow the tablets with water or any other nonalcoholic drink.
If you are taking tamoxifen to prevent breast cancer, you will probably take it for five years. If you are taking tamoxifen to treat breast cancer, your doctor will decide how long your treatment will last. Do not stop taking tamoxifen without talking to your doctor.
If you forget to take a dose of tamoxifen, take the missed dose as soon as you remember it, and take your next dose as usual. However, if it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Tamoxifen is also used sometimes to induce ovulation (egg production) in women who do not produce eggs but wish to become pregnant. Tamoxifen is also sometimes used to treat McCune-Albright syndrome (MAS; a condition that may cause bone disease, early sexual development, and dark colored spots on the skin in children). Talk to your doctor about the possible risks of using this drug for your condition.
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
Before taking tamoxifen,
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Tamoxifen may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
Some side effects can be serious. If you experience any of the following symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:
Tamoxifen may increase the risk that you will develop other cancers, including liver cancer. Talk to your doctor about this risk.
Tamoxifen may increase the risk that you will develop cataracts (clouding of the lens in the eye) that may need to be treated with surgery. Talk to your doctor about this risk.
Tamoxifen may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.
Keep tamoxifen in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).
Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( Web Site) for more information if you do not have access to a take-back program.
It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. Web Site
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at Web Site. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.
Symptoms of overdose may include:
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
¶ This branded product is no longer on the market. Generic alternatives may be available.
AHFS® Consumer Medication Information. © Copyright, The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.
Selected Revisions: January 15, 2018.