What is Nolvadex®(tamoxifen)?

Tamoxifen is a hormone therapy used to treat breast cancers that are hormone receptor positive (HR+). The brand names of tamoxifen are Nolvadex® (tamoxifen) and Soltamox™ (tamoxifen). (Soltamox™ is an oral liquid form.) Tamoxifen has been available in a generic form since 2006.1

Tamoxifen may be used as an adjuvant treatment (after surgery) for early-stage breast cancer that is estrogen receptor-positive. It may also be used to reduce the risk of developing breast cancer in women who are at high risk of developing the disease, such as those with a strong family history of breast cancer. Tamoxifen may also be used for women who have had ductal carcinoma in situ (DCIS), after radiation and breast surgery, to help decrease the risk of a more invasive form of breast cancer. Tamoxifen may also be used for estrogen receptor-positive breast cancer has metastasized (spread beyond the breast to other areas of the body).2

What is tamoxifen?

Tamoxifen is considered an antiestrogen medication.

How does tamoxifen work?

Many breast cancers have estrogen receptors on the surface of their cells. Estrogen can connect to these receptors and stimulate the growth of these breast cancers. Tamoxifen blocks estrogen and may stop or slow the growth of cancerous cells.2

What are some of the possible side effects of tamoxifen?

Tamoxifen may cause serious side effects. In patients taking tamoxifen, some serious and life-threatening side effects have occurred, including uterine cancer, stroke, and pulmonary embolism (a blood clot in the lungs).2,3

Tamoxifen may increase the risk of developing blood clots and cataracts.2,3

Tamoxifen may increase the risk of developing other cancers, such as liver cancer.2

The most common side effects experienced by patients taking tamoxifen include3:

  • Hot flashes
  • Vaginal discharge
  • Changes in mood
  • Vaginal bleeding
  • Nausea
  • Swelling

Other potential side effects of tamoxifen include2:

  • Increased bone or tumor pain
  • Fatigue
  • Dizziness
  • Depression
  • Headache
  • Hair thinning
  • Weight loss
  • Stomach cramps
  • Constipation

These are not all the possible side effects of tamoxifen. Patients should talk to their doctor about what to expect with treatment with tamoxifen.

Things to know about tamoxifen

Before starting treatment with tamoxifen, patients should talk to their doctor about all their health conditions, as well as anymedications (prescription and over-the-counter), vitamins, and herbal supplements they are taking. Some medications or supplements may interfere with each other and may cause side effects.2

Before beginning tamoxifen, patients should discuss with their doctor all their health conditions, including2:

  • High cholesterol
  • History of blood clots in the lungs or legs
  • History of stroke or heart attack
  • High blood pressure
  • Diabetes
  • If patients are pregnant, or planning to become pregnant
  • If patients are breastfeeding, or planning to breastfeed

Tamoxifen may cause harm to an unborn baby and should not be used by women who are pregnant. While taking tamoxifen, men with female partners who can become pregnant, and women who can become pregnant, should both use effective contraceptives during treatment and for a period of time after completing treatment (patients should discuss appropriate birth control methods, and how long they need to use them, with their doctor).3

It is not known if tamoxifen can pass into breastmilk. Women should not breastfeed during tamoxifen treatment and for three months after the final dose of tamoxifen.3

Receiving tamoxifen

Tamoxifen comes in a tablet and oral liquid form. Your doctor will determine the appropriate tamoxifen dosing regimen and administration schedule for you. It is important to follow this schedule exactly as instructed, and not to stop taking tamoxifen or any accompanying medications on your own, unless you are instructed to do so by your doctor.2

For more information, read the full prescribing information for Soltamox or the full prescribing information for Nolvadex.

Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their tamoxifen regimen.

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Written by: Editorial Team | Last reviewed: October 2020.