Estrogen has several side effects. First of all, estrogen can stimulate endometrial lesions. Female estrogen, androgen and progesterone affect each other and are mutually regulated. If estrogen is secreted in excess under the action of drugs and the pituitary gland of the body, the endometrium will cause abnormal proliferation under the action of estrogen for a long time, thus causing lesions of the endometrium. Secondly, the uterus under the effect of estrogen for a long time will lead to fibroids, and the breast under the effect of estrogen will also become diseased, leading to breast hyperplasia or even breast cancer. In addition, estrogen supplementation has the risk of causing venous thrombosis and needs to be used under the guidance and monitoring of a physician.