Drooling after chemotherapy for breast cancer may be caused by side effects of chemotherapy or other factors. 1. Side effect of chemotherapy: chemotherapy drugs may stimulate the oral mucosa, which will reflexively cause salivary glands to increase secretion, which will lead to hypersalivation, and it will get better after stopping chemotherapy drugs. Drooling caused by chemotherapeutic drugs is often accompanied by other side effects, such as hair loss, decreased blood cells, vomiting and nausea. 2. Other reasons: for example, cerebrovascular disease, cerebral palsy and other swallowing dysfunction can cause hypersalivation; in addition, eating too much acid may also lead to hypersalivation. People with hypersalivation after breast cancer chemotherapy need to reflect the situation to the attending doctor in time and follow the doctor’s advice to use chemotherapy drugs, patients should not use chemotherapy drugs by themselves to avoid adverse results.