Blisters on the mouth may be caused by an acute illness or a chronic illness, and a distinction needs to be made. Allergic reaction is a common cause of blisters on the mouth, because the lips are in contact with some allergic substances, so there will be an allergic reaction, usually mainly caused by some cosmetics, but also may be caused by some irritating food. Bacterial infection is because the lips are always licked will lead to the residue of saliva, this time will provide the conditions for the growth of bacteria, this time will trigger a bacterial infection, bacterial infection generally need to survive the environment, the survival environment is suitable, this time the mouth will blister. Some children may be due to hand, foot and mouth disease, which is an infectious disease that occurs mainly in children, and this disease makes it easy to have blisters on the lips. Oral cancer is a kind of cancer, which can be caused by many reasons, but this disease will be reflected on the lips as blisters on the mouth. Perioral dermatitis is mainly a facial rash caused by skin irritation, mainly because the skin is irritated by some substances. This eventually causes a strong reaction in the skin. There are many reasons for blisters on the mouth, and in daily life, it is important to pay attention to the hygiene of the lips to prevent some diseases from arising. When this symptom occurs, you can choose to take internal and external use together, so that the disease can get better faster.