Oral blistering may be caused by over-irritation, oral herpes, hand, foot and mouth disease and other factors. 1. Overstimulation: For example, eating too hot food, which causes irritation to the oral cavity, can cause oral blistering, which may also be accompanied by pain, burning sensation and other abnormal manifestations. 2. Oral herpes: usually caused by herpes simplex virus infection, which can cause blisters to appear in the mouth and may be accompanied by pain, bad breath, drooling, fever and other symptoms. 3. Hand, foot and mouth disease: caused by enterovirus infection, which can cause blisters to appear in the mouth, hands and feet, accompanied by symptoms such as loss of appetite, cough, runny nose and fever. Blisters in the mouth, and the presence of abnormal manifestations, may be the existence of disease factors, it is recommended to seek medical examination and treatment as soon as possible.