Dexamethasone is a hormone-based drug, and oral dexamethasone taken before chemotherapy has the effect of preventing allergic reactions caused by chemotherapy drugs, and may also reduce or prevent vomiting reactions. Such as common paclitaxel or docetaxel, if not used, may produce more serious allergic reactions, and oral dexamethasone or other hormone drugs, can prevent such reactions. Chemotherapy is a very common method of anti-tumor treatment. Adjuvant chemotherapy can be done after surgery, and some tumors can also be treated with chemotherapy before surgery to shrink the tumor, lower the stage, and then strive for surgical cure. For advanced malignant tumors, chemotherapy can play a role in prolonging the survival period and reducing the pain of patients. The most common side effects of chemotherapy are nausea, vomiting and other gastrointestinal reactions. In addition to dexamethasone, antiemetic drugs such as ondansetron can also be applied.