Side effects of Exemestane may appear 2~3 days after taking it, there may be no obvious side effects, the specific situation varies from person to person, and it is impossible to make a generalization. Exemestane is an aromatase inhibitor used in the treatment of breast cancer, and its principle of action is to achieve anti-tumor purposes by inhibiting the activity of aromatase. It is clinically indicated for postmenopausal patients with advanced breast cancer that develops to hormone receptor positive after tamoxifen application. Patients will experience different degrees of side effects after taking the drug, mostly in 2~3 days after taking the drug, which can be manifested as gastrointestinal symptoms such as nausea and vomiting, abdominal pain, constipation, dyspepsia, etc., and can cause neurological symptoms such as dizziness and headache, insomnia, and mood changes. It may also cause elevated liver aminotransferases and bilirubin, osteoporosis, bone fracture, alopecia, and peripheral edema. Some patients may not experience any significant symptoms. This drug belongs to the prescription drugs, in order to ensure the safety of drug use, clinically recommended patients to follow the doctor’s instructions to take.