Tamoxifen, sold under the brand name Nolvadex among others, is a medication that is used to prevent breast cancer in women and treat breast cancer in women and men.[8] It is also being studied for other types of cancer.[8] It has been used for Albright syndrome.[9] Tamoxifen is typically taken daily by mouth for five years for breast cancer.[9]

Serious side effects include a small increased risk of uterine cancerstroke, vision problems, and pulmonary embolism.[9] Common side effects include irregular periods, weight loss, and hot flashes.[9] It may cause harm to the baby if taken during pregnancy or breastfeeding.[9] It is a selective estrogen-receptor modulator (SERM) and works by decreasing the growth of breast cancer cells.[9][10] It is a member of the triphenylethylene group of compounds.[11]

Tamoxifen was initially made in 1962, by chemist Dora Richardson.[12][13] It is on the World Health Organization’s List of Essential Medicines, the safest and most effective medicines needed in a health system.[14] Tamoxifen is available as a generic medication.[9] The wholesale price in the developing world is about US$0.07–0.23 per day.[15] In the United States, it costs about $1 per day.[9] In 2016, it was the 238th most prescribed medication in the United States, with more than two million prescriptions.[16]

Medical uses[edit]

Breast cancer[edit]

Tamoxifen is used for the treatment of both early and advanced estrogen receptor-positive (ER-positive or ER+) breast cancer in pre- and post-menopausal women.[17] Additionally, it is the most common hormone treatment for male breast cancer.[18] It is also approved by the FDA for the prevention of breast cancer in women at high risk of developing the disease.[19] It has been further approved for the reduction of contralateral (in the opposite breast) cancer. The use of tamoxifen is recommended for 10 years.[20]

In 2006, the large STAR clinical study concluded that raloxifene is also effective in reducing the incidence of breast cancer. Updated results after an average of 6.75 years of follow up found that raloxifene retains 76% of tamoxifen’s effectiveness in preventing invasive breast cancer, with 45% fewer uterine cancers and 25% fewer blood clots in women taking raloxifene than in women taking