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Side Effects of Tamoxifen

Tamoxifen can be used to:

  • Treat hormone receptor-positive breast cancer (learn more)
  • Lower risk among women at high risk of breast cancer who haven’t been diagnosed (learn more)

Tamoxifen has fewer side effects than chemotherapy. For example, tamoxifen doesn’t cause nausea.

Side effects in women

Menopausal symptoms (such as hot flashes) are common in women who take tamoxifen [103]. 

Although menopausal symptoms may become less frequent and less intense over time, they can still be hard to manage. If you have symptoms, talk with your health care provider about ways to treat them.

The most serious health risks of tamoxifen, such as endometrial cancer (cancer of the lining of the uterus) and blood clots in the lungs, are rare [103].

Figure 5.10 lists some possible side effects and health risks of tamoxifen in women.   

Figure 5.10: Side effects and health risks of tamoxifen in women


  • Hot flashes and night sweats
  • Irregular periods or spotting (uterine bleeding)
  • Loss of sex drive
  • Vaginal discharge
  • Vaginal dryness or itching


  • Blood clots in the large veins (deep venous thrombosis)
  • Blood clots in the lungs (pulmonary emboli)
  • Bone loss (premenopausal women only)
  • Cancer of the uterus (uterine or endometrial cancer)
  • Cataracts
  • Stroke

Adapted from Rimawi MF and Osborne CK [103].


Side effects in men

In men, possible side effects of tamoxifen include [103-105]:

  • Blood clots in the large veins (deep vein thrombosis)
  • Blood clots in the lungs (pulmonary emboli)
  • Cataracts
  • Headache
  • Hot flashes
  • Impotence
  • Loss of sex drive
  • Nausea and vomiting
  • Skin rash
  • Stroke

Side effects of tamoxifen versus side effects of aromatase inhibitors

Although both aromatase inhibitors and tamoxifen can cause menopausal symptoms, such as hot flashes, many of their side effects differ.

Learn about how the side effects of these hormone therapies compare


  • If you or a loved one needs more information about breast health or breast cancer, call the Komen Breast Care Helpline at 1-877 GO KOMEN (1-877-465-6636). All calls are answered by a trained specialist or oncology social worker in English and Spanish, Monday through Friday from 9:00 a.m. to 10:00 p.m. ET. You can also email the helpline at helpline@komen.org.
  • We offer an online support community through our closed Facebook Group – Komen Breast Cancer group. The Facebook group provides a place where those with a connection to breast cancer can discuss each other’s experiences and build strong relationships to provide support to each other. Visit Facebook and search for “Komen Breast Cancer group” to request to join the closed group.
  • Our fact sheets, booklets and other education materials offer additional information.

Updated 05/20/21