An estrogen antagonist - It is commonly used to treat breast cancer
FDA Alerts
For women with ductal carcinoma in situ (DCIS) and women at high risk for breast cancer: serious and life-threatening events associated with tamoxifen in the risk reduction setting include uterine malignancies, stroke, and pulmonary embolism. Incidence rates for these events have been estimated from the NSABP P-1 trial (median length of follow-up 6.9 years).
Uterine malignancies consist of both endometrial adenocarcinoma (incidence rate per 1000 women-years of 2.2 for tamoxifen versus 0.71 for placebo) and uterine sarcoma (incidence rate per 1000 women-years of 0.17 for tamoxifen versus 0 for placebo).
For stroke, the incidence rate per 1000 women-years was 1.43 for tamoxifen versus 1 for placebo.
For pulmonary embolism, the incidence rate per 1000 women-years was 0.75 for tamoxifen versus 0.25 for placebo.
Health care providers should discuss the potential benefits versus the potential risks of these serious events with women at high risk of breast cancer and women with DCIS considering tamoxifen to reduce their risk of developing breast cancer.
The benefits of tamoxifen outweigh its risks in women already diagnosed with breast cancer.
TAMOXIFEN (ta MOX i fen) blocks the effects of estrogen. It is commonly used to treat breast cancer. It is also used to decrease the chance of breast cancer coming back in women who have received treatment for the disease. It may also help prevent breast cancer in women who have a high risk of developing breast cancer.
This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.
What should I tell my health care provider before I take this medicine?
They need to know if you have any of these conditions:
Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. You can take it with or without food. Take your medicine at regular intervals. Do not take your medicine more often than directed. Do not stop taking except on your doctor's advice.
A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.
Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for selected conditions, precautions do apply.
Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.
What if I miss a dose?
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.
What should I watch for while using this medicine?
Visit your doctor or health care professional for regular checks on your progress. You will need regular pelvic exams, breast exams, and mammograms. If you are taking this medicine to reduce your risk of getting breast cancer, you should know that this medicine does not prevent all types of breast cancer. If breast cancer or other problems occur, there is no guarantee that it will be found at an early stage.
Do not become pregnant while taking this medicine or for 2 months after stopping this medicine. Stop taking this medicine if you get pregnant or think you are pregnant and contact your doctor. This medicine may harm your unborn baby. Women who can possibly become pregnant should use birth control methods that do not use hormones during tamoxifen treatment and for 2 months after therapy has stopped. Talk with your health care provider for birth control advice.
Do not breast feed while taking this medicine.
Last Updated: September 14, 2009
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