tamoxifen

noun

ta·​mox·​i·​fen tə-ˈmäk-sə-ˌfen 

: an estrogen antagonist C₂₆H₂₉NO used in the form of its citrate especially to treat postmenopausal breast cancer

Examples of tamoxifen in a Sentence

Recent Examples on the Web

For example, mangosteen increases the effectiveness of tamoxifen, a drug commonly used for breast cancer.12 Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. —Amy Brownstein, Verywell Health, 7 Aug. 2025

Thank you, Dora, on behalf of all the women tamoxifen has helped, and all the women tamoxifen will help. —Katie Hafner, Scientific American, 31 Oct. 2024

However, there have been no clinical trials on the benefits of flaxseed in humans with breast cancer during tamoxifen therapy.7 Experts recommended that people with breast cancer only use flaxseed in amounts found in foods and avoid using flaxseed supplements. —Brittany Lubeck, Verywell Health, 16 July 2025

In general, though, the risk of uterine cancer from tamoxifen use is low. —Carrie Madormo, Health, 13 July 2025

Word History

Etymology

probably by recombination & alteration of trans-, oxy, and clomiphene

First Known Use

1972, in the meaning defined above

Medical Definition

tamoxifen

noun

ta·​mox·​i·​fen ta-ˈmäk-si-ˌfen 

: a selective estrogen receptor modulator that acts as an estrogen antagonist in breast tissue and is administered orally in the form of its citrate C₂₆H₂₉NO·C₆H₈O₇ especially to treat breast cancer or reduce the risk of its development or reoccurrence see nolvadex