The patient had a series of oral symptoms after taking synergistic sulfonate tablets to treat sore throat, and had a similar medical history in the past, so the patient was most likely diagnosed as drug allergic stomatitis. When collecting medical history, special attention should be paid to asking about the history of drug allergy and medication. Direct counting of eosinophils is the most helpful for diagnosis. The treatment of this disease should first avoid antigenic substances, namely allergens. Stop using or eating drugs and foods suspected of allergies, and try to avoid animals, plants, chemical raw materials and other allergenic substances. Drink plenty of water to accelerate the discharge of allergens.