The National Cancer Institute (NCI) indicates that Tamoxifen, an oral medication approved by the Food and Drug Administration, has been used for well over thirty years to treat breast cancer in both women and men. This drug is known as a selective estrogen receptor modulator (SERM); specifically, it blocks the female hormone, estrogen, from acting on breast cells in breast cancers that are hormone receptive or hormone positive. This medication is used also in women who have a particularly high risk of developing breast cancer as well as extensive breast tissue growth or gynecomastia in men.
Uterine Cancer
Tamoxifen stimulates estrogen in the lining of the uterus. According to the NCI, women who take Tamoxifen are at an increased risk for two types of uterine malignancy: endometrial (uterine lining) cancer and uterine sarcoma (uterine wall). The risk is considered small, and the benefits of this drug are viewed usually as outweighing the potential consequences.
Circulatory
According to the NCI, the Breast Cancer Prevention Trial, funded by that agency, found that being on Tamoxifen for several years slightly increases the risk for blood clots, pulmonary emboli and strokes. Changes in terms of easy bruising or bleeding easily also may result. This effect is prominent when Tamoxifen is combined with chemotherapy. Thus, Tamoxifen is contraindicated in individuals who have a history of blood clots or circulatory conditions of this type.
Hot Flashes
Some of the most common reported side effects with Tamoxifen are menopausal symptoms such as hot flashes, irregular menstrual periods, vaginal discharge or vaginal dryness and changes in mood. These symptoms will vary according to the individual but are not considered to be severe effects.
Gastrointestinal
At times, stomach problems such as nausea and vomiting, an upset stomach or indigestion may be reported, however these symptoms usually are not severe.
