A blister on the mouth can be caused by trauma, herpes, impetigo, etc. It can be improved by general treatment and medication. 1. Trauma: If it is caused by repeated friction. Most of the smaller blisters can be self-absorbed and subside, local povidone-iodine disinfection can be, the larger blisters can be punctured and pumped, local povidone-iodine disinfection, pay attention to the local to keep clean and dry. Pay attention to light diet, avoid spicy stimulation and other foods. 2. Herpes: If it is a viral infection herpes simplex and the formation of blisters. You can take oral acyclovir tablets and vasiclovir tablets under doctor’s guidance. At the same time, apply acyclovir cream externally, or spray acyclovir cream externally. 3. Impetigo: If the blisters are formed as a result of bacterial infection caused by impetigo, the pustules need to be punctured in time to release the blister fluid. At the same time, under the guidance of the doctor to use topical drugs to prevent infection, such as mupirocin ointment. If accompanied by pain and other uncomfortable symptoms, you can give ibuprofen granules and other pain relieving drugs. When you have a blister on your mouth, you should pay attention to maintaining local hygiene, eat a light diet, and seek medical attention in time. Under the guidance of a professional doctor to follow the doctor’s instructions to use drugs, avoid blind use of drugs, so as not to cause adverse consequences.