Breast cancer endocrine drugs are generally more effective when taken 4 to 6 weeks after surgery (if no chemotherapy is given after surgery), or when chemotherapy is finished and lasts for 5 years. Specifically what time period on a particular day is effective is not clearly defined and can be taken according to the instructions. Breast cancer endocrine therapy is used for hormone receptor-positive breast cancer, the overall time recommended to take the drug for 5 years, some high-risk patients, such as less than 35 years old at the time of diagnosis, larger tumor size, positive lymph nodes and other patients may need to extend to 10 years. Breast cancer endocrine drugs specific to what time period on a certain day to take the effect is not clearly defined, it is recommended to take according to the instructions. For endocrine drugs with no special requirements, if taking them before meals produces gastrointestinal reactions such as nausea and bloating, you can choose to take them after meals, which can appropriately reduce gastrointestinal side effects. There are different kinds of endocrine drugs for breast cancer, such as tamoxifen, letrozole, anastrozole, exemestane, etc. Each drug has its own characteristics, side effects and requirements for taking the drug, and it is recommended that the patients must apply them under the guidance of the doctor, and must not take them by themselves.