Answer:
"The known, serious side effects of tamoxifen are blood clots, strokes, uterine cancer, and cataracts. Other side effects of tamoxifen are similar to the symptoms of menopause. The most common side effects are hot flashes and vaginal discharge. Some women experience irregular menstrual periods, headaches, fatigue, nausea and/or vomiting, vaginal dryness or itching, irritation of the skin around the vagina, and skin rash. As with menopause, not all women who take tamoxifen have these symptoms. Men who take tamoxifen may experience headaches, nausea and/or vomiting, skin rash, impotence, or a decrease in sexual interest."
Source:
http://www.cancer.gov/cancertopics/factsheet/Therapy/tamoxifen