What is tamoxifen?
Tamoxifen blocks the actions of estrogen, a female hormone. Certain types of breast cancer require estrogen to grow.
Tamoxifen is used to treat some types of breast cancer in men and women. Tamoxifen is also used to lower a woman's chance of developing breast cancer if she has a high risk (such as a family history of breast cancer).
Tamoxifen may also be used for purposes not listed in this medication guide.
What is the most important information I should know about tamoxifen?
Do not use tamoxifen if you are pregnant. It could harm the unborn baby. Use a barrier form of birth control (such as a condom or diaphragm with spermicide) while you are using this medication and for at least 2 months after your treatment ends.
You should not use tamoxifen if you are allergic to it, or if you have a history of blood clots in your veins or your lungs, or if you are also taking a blood thinner such as warfarin (Coumadin).
Before using tamoxifen, tell your doctor if you have liver disease, high triglycerides (a type of fat in the blood), a history of cataract, or a history of stroke or blood clot. Also tell your doctor if you if you are receiving chemotherapy or radiation treatment.
If you are taking tamoxifen to reduce your risk of breast cancer, you may need to take your first dose while you are having a menstrual period. You may also need to have a pregnancy test before you start taking tamoxifen, to make sure you are not pregnant. Follow your doctor's instructions.
Taking tamoxifen may increase your risk of uterine cancer, stroke, or a blood clot in the lung, which can be fatal. Talk with your doctor about your specific risks in taking this medication.
To make sure this medication is not causing harmful effects, your doctor may want you to have mammograms and to perform routine breast self exams on a regular basis. Your liver function may also need to be tested. Visit your doctor regularly.
What should I discuss with my healthcare provider before taking tamoxifen?
You should not use tamoxifen if you are allergic to it, or if you have:
To make sure you can safely take tamoxifen, tell your doctor if you have any of these other conditions:
liver disease;
high cholesterol or triglycerides (a type of fat in the blood);
a history of stroke or blood clot;
a history of cataract; or
if you are receiving chemotherapy or radiation.
Taking tamoxifen may increase your risk of uterine cancer, stroke, or a blood clot in the lung, which can be fatal. Talk with your doctor about your specific risks in taking this medication.
FDA pregnancy category D. Do not use tamoxifen if you are pregnant. It could harm the unborn baby. Use a barrier form of birth control (such as a condom or diaphragm with spermicide) while you are using this medication and for at least 2 months after your treatment ends.
Hormonal contraception (such as birth control pills, injections, implants, skin patches, and vaginal rings) may not be effective enough to prevent pregnancy during your treatment.
It is not known whether tamoxifen passes into breast milk or if it could harm a nursing baby. However, this medication may slow breast milk production. You should not breast-feed while taking tamoxifen.