Common side effects of tamoxifen include hot flashes, vaginal dryness, vaginal discharge and a loss of sex drive.

Rare, but potentially serious side effects of tamoxifen include a blood clot in the lungs, called pulmonary embolism, or blood clots in the major veins of the legs, called deep vein thrombosis, bone loss (for premenopausal women), cancer of the uterus, cataracts and stroke. Although rare, because some women may develop uterine cancer from taking tamoxifen, routine gynecological exams are recommended.