Breast cancer patients can usually take endocrine drugs 2 to 3 days after surgery. However, if chemotherapy is needed, it is recommended to take endocrine drugs after chemotherapy. Most of the breast cancer is related to estrogen, and the treatment of breast cancer can be achieved if estrogen secretion or application is reduced. Endocrine therapy for breast cancer is achieved by suppressing the level of estrogen that is associated with breast cancer. Usually, after the surgery, as the patient’s body is weak and the endocrine secretion may be in a state of disturbance, the use of endocrine drugs should be avoided at this time, or else it will not have a better effect. Therefore, it is usually recommended to take the medication after the patient’s body has recovered a little bit in about 2~3 days after the surgery. In addition, endocrine therapy and chemotherapy at the same time may reduce the efficacy, so endocrine therapy is usually carried out after chemotherapy. Endocrine therapy for breast cancer may also cause side effects such as loss of appetite, nausea, dizziness, facial flushing, skin rash, etc. A few patients may also have a decrease in white blood cells and platelets, and abnormal liver function. It is recommended that patients use medication under the guidance of a doctor, do not self-medicate and delay the condition.