Side Effects of HRT Side effects that can occur with all forms of estrogen but are more frequent with oral estrogen include: Headaches. Fluid retention. Vaginal discharge. Spotting or darkening of the skin, particularly on the face. Weight gain Rarely, an increased growth of preexisting uterine fibroids or a worsening of endometriosis. Breast tenderness. Nausea. Pulmonary emboli. Deep venous thrombosis. These effects are not permanent. They just go away after few weeks of use. Skin irritation may be caused due to estrogen patch. Replacement of ring must be done after every three months. If during this duration of three months, by chance ring may fall, then rinse it with lukewarm water and reinsert it. Women suffering from liver or gallbladder disease may make use of vaginal cream. For full list of side effects refer Drug Reference. (Drug Reference is not available in all systems.) Things to Remember. Current studies shows that HRT using estrogen and progestin is a very short term treatment for menopausal symptoms. Some studies on women taking estrogen without progestin are still in progress. There is a risk of endometrial cancer, if ERT alone is done. But this risk is less in the case when estrogen is taken in combo with progestin. i.e HRT. There is no risk of uterine cancer in those women who have had a hysterectomy. If a women having uterus is unable to face the side effects of HRT, then she may consider ERT. But this can be done only if, testing shows no abnormalities of endometrium. Precancerous changes of the endometrium is closely observed. Pelvic xam and endometrial biopsy must be done annually. It has been studied that different types estrogens do not possess different effects. Some females prefer to take estrogens that do not come from animal products.