Melasma (tan or brown patches) may develop on the forehead, cheeks, or temples. These may persist even after the estrogen is stopped. Estrogens may cause an increase in the curvature of the cornea, and, therefore, patients with contact lenses may develop intolerance to their lenses.
Blood clots: Blood clots are occasional but serious side effects of estrogen therapy and are dose-related, that is, they occur more frequently with higher doses. Cigarette smokers are at a higher risk than non-smokers. Therefore, patients requiring estrogen therapy are strongly encouraged to quit smoking.
Uterine cancer: Estrogens can promote a build-up of the lining of the uterus or endometrium (endometrial hyperplasia) and increase the risk of endometrial cancer. At diagnosis, endometrial cancers in estrogen users are generally of an earlier stage and a lesser degree of malignancy than in non-users. Survival, therefore, is better. The addition of a progestin to estrogen therapy prevents endometrial cancer from developing.
Breast cancer: Conflicting data exists on the association between estrogen therapy and breast cancer. There may be a small increase in risk. It is not clear if the addition of a progestin during estrogen therapy reduces the risk of breast cancer (as it does for uterine cancer). The Women's Health Initiative found that postmenopausal women (50-79 years old) taking conjugated estrogens, 0.625 mg daily, in combination with medroxyprogesterone, 2.5 mg daily, for five years, had an increased risk of heart attacks, stroke, breast cancer, and blood clots, while postmenopausal women taking conjugated estrogens without progesterone experienced only increased strokes but not increased blood clots, heart disease, or breast cancer.
Quick GuideWhat to Expect During Menopause as You Age
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