Side effects: The Women's Health Initiative (WHI) study reported increased risks of heart attack, stroke, invasive breast cancer, pulmonary emboli (blood clots in the lungs), and deep vein thromboses (blood clots in the legs) in postmenopausal women (50-79 years) during 5 years of treatment with conjugated estrogens (0.625 mg) combined with medroxyprogesterone acetate (2.5 mg) relative to placebo (sugar pills). Estrogens may cause breast tenderness, weight gain, fluid retention, gall bladder disease, and vaginal bleeding, along with increasing the risk of breast or endometrial cancers. They also increase the risk of blood clots and may increase the risk of complications from clots, such as stroke, heart attack, or thrombophlebitis. Call your doctor immediately if you experience any of the following side effects: