Tamoxifeninfo-icon is a hormonal therapyinfo-icon used to reduce the risk of cancer returning. It is a SERMinfo-icon, or selective estrogen receptor modulatorinfo-icon, a medicineinfo-icon that prevents estrogeninfo-icon signals from getting to breast cancer cells. They are given as daily pills. SERMs are part of a family of medicines known as estrogen blockers. 

This medicine may also be called Nolvadex or Soltamox, in a liquid form.

How Tamoxifen Works

Tamoxifeninfo-icon works by blocking estrogeninfo-icon from reaching estrogen receptors on breast cancer cells. Without the estrogen, the cancer cells can’t grow as well as they can with it.

Who Gets Tamoxifen

Tamoxifeninfo-icon is standard treatment for premenopausalinfo-icon and perimenopausalinfo-icon women with hormone receptorinfo-icon-positive breast cancer. In postmenopausalinfo-icon women, tamoxifen may be used alone or before an aromatase inhibitorinfo-icon.

In early-stage breast cancerinfo-icon, no matter what your menopausal status, tamoxifen used after other treatment reduces the risk of cancer coming back. The benefit happens during the therapyinfo-icon and continues afterward for many years. Studies show breast cancer deaths to be down 30 percent in women 15 years beyond the start of tamoxifen treatment.

How Tamoxifen Is Given

Tamoxifeninfo-icon is taken daily as a pill or in liquid form as tamoxifen citrate (Soltamox). Because your body produces estrogeninfo-icon every day, it’s important to take tamoxifen every day.

In the past, it was standard to take tamoxifen for 5 years, but recent research shows that taking tamoxifen for a total of 10 years further lowers the chance of the cancer returning. How long you take tamoxifen depends on your menopausal status:

Note that aromatase inhibitors are the standard of careinfo-icon for postmenopausal women. If you are postmenopausal and take an AI without taking tamoxifen before, the standard of care remains 5 years of AI therapyinfo-icon.

Side Effects and Things to Remember

Some antidepressants can affect the way your body breaks down tamoxifeninfo-icon. Research shows that bupropion (Wellbutrin), duloxetineinfo-icon (Cymbalta), fluoxetineinfo-icon (Prozac), paroxetine (Paxilinfo-icon) and sertralineinfo-icon (Zoloftinfo-icon) may stop tamoxifen from working as well as it could. It’s also possible that common arthritis medicines (Celebrex), antacids (Tagamet, Zantac) and antihistamines (Atarax, Benadryl) could interact poorly with tamoxifen.

It is not known whether these medicines make tamoxifen less effective. To keep tamoxifen working as well as possible, tell your doctor about all medicines and supplements you take. It’s likely there are good options that won’t affect your tamoxifen treatment.

Like all medicines, tamoxifen has side effects. The issues may be few or none, cause some problems, or truly disrupt your life. Common side effects include:

Serious side effects are rare, but tamoxifen may cause:

Tamoxifen also can lower cholesterol and lessen menopauseinfo-icon-related bone loss if you are postmenopausalinfo-icon. If you are premenopausalinfo-icon, tamoxifen can cause bone loss.

Talk with your doctor if you had a heart attack or blood clots before. Call your doctor immediately if you have chest pain, abnormalinfo-icon vaginal bleeding, dizziness, leg swelling, severe headache or other symptoms.

Because tamoxifen can harm a fetus, use safe birth control while taking it if you are premenopausal or still have a period every now and then. Discuss this important issue and any side effects you feel with your healthcare team so they can help you.

Your doctor, pharmacistinfo-icon or nurseinfo-icon can help you manage your side effects. You can also go to our section on Side Effects for more information.


November 4, 2019
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