What is Nolvadex® (tamoxifen)?

Tamoxifen is used to treat certain people with breast cancer that is hormone receptor-positive (HR+). The brand names of tamoxifen are Nolvadex® and Soltamox™. Tamoxifen has also been available in a generic form since 2006.1

Tamoxifen is used to:2-4

  • Treat HR+ breast cancer that has spread to other parts of the body (metastatic)
  • Treat early-stage HR+ breast cancer after surgery and radiation
  • Reduce the chance of developing breast cancer in the other breast after surgery and radiation
  • Reduce the risk of invasive breast cancer in people with ductal carcinoma in situ (DCIS) breast cancer after surgery and radiation
  • Reduce the risk of getting breast cancer in people with a high risk of getting breast cancer

What are the ingredients in Nolvadex?

The active ingredient in Nolvadex is tamoxifen.2-4

How does tamoxifen work?

Tamoxifen is an anti-estrogen drug. 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, which may stop or slow the growth of cancer cells.2

What are the possible side effects of tamoxifen?

The most common side effects of tamoxifen include:3,4

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

Tamoxifen may also cause serious side effects, including:2-4

  • Liver problems, including liver cancer
  • Other cancers
  • High levels of calcium in the blood (hypercalcemia)
  • Decreased blood cell counts
  • Eye problems, including cataracts

Tamoxifen has a boxed warning, the strictest warning from the U.S. Food and Drug Administration (FDA). This is because it may cause severe side effects, including:2-4

  • Uterine problems, including uterine cancer, endometriosis, fibroids, and irregular menstrual periods
  • Blood clots in your veins or lungs
  • Stroke

Tell your doctor if you have any new or worsening side effects while taking tamoxifen.

These are not all the possible side effects of tamoxifen. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with tamoxifen.

Things to know about tamoxifen

Do not take tamoxifen if you have DCIS breast cancer or a high risk of breast cancer and you:2-4

  • Need to take the blood thinner drug warfarin, or
  • Have a history of blood clots in your veins or lungs

Before beginning tamoxifen, tell your doctor if you have:2-4

  • Uterine cancer or other problems with your uterus
  • Irregular menstrual periods, no menstrual periods, or abnormal vaginal bleeding
  • Current or previous blood clots
  • A history of stroke

Tamoxifen can harm an unborn baby. If you or your partner can become pregnant, you should use birth control during treatment and for some time after the last dose of tamoxifen. You should also not breastfeed during treatment with tamoxifen and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking tamoxifen.3,4

Before beginning treatment for breast cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

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

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Written by: Editorial Team | Last reviewed: March 2021