Spitting white foam after chemotherapy may be caused by epilepsy, toxic reaction of chemotherapy drugs and other reasons. 1. Epilepsy: chemotherapy can cause damage to the central nervous system and peripheral nerves, damage to the central nervous system may lead to epilepsy, in addition to foaming at the mouth, there will be sudden collapse, limb convulsions, corns and other symptoms. 2. Toxic reaction to chemotherapy drugs: gastrointestinal reaction is the most common side effect of chemotherapy, the drug stimulates the mucosa of the gastrointestinal tract and stimulates the vomiting center causing nausea, vomiting and other symptoms, which may be manifested as vomiting white foam or foamy sputum. After chemotherapy vomiting white foam should be timely to the hospital, improve the relevant examination to clarify the cause of the disease, under the guidance of the doctor symptomatic treatment.