At this time, use of estrogens in the menopause is not known to cause such blood clotting, but this has not been fully studied and there could still prove to be such a risk. You should not receive estrogen if you are pregnant. If this should occur, there is a greater than usual chance that the developing child will be born with a birth defect, although the possibility remains fairly small. Every possible effort should be made to avoid exposure to estrogens during pregnancy. If exposure occurs, see your doctor.
Vomiting is less common.
Estrogens may cause breast tenderness or enlargement and may cause the breasts to secrete a liquid. These effects are not dangerous . Estrogens may cause benign fibroid tumors of the uterus to get larger. Women taking oral contraceptives develop, on rare occasions, a tumor of the liver which can rupture and bleed into the abdomen and may cause death. So far, these tumors have not been reported in women using estrogens in the menopause, but you should report any swelling or unusual pain or tenderness in the abdomen to your doctor immediately.