Mouth ulcers are generally caused by localized mucosal erosion in the patient's mouth, often due to internal heat in the body or a deficiency of certain nutrients. They are not contagious and thus do not spread from one person to another.

However, it is advised that patients pay close attention to oral hygiene, rinse their mouth promptly after meals, and brush their teeth regularly in the morning and evening using the correct brushing technique to maintain good oral care. When there is pain or noticeable erosion due to the mouth ulcer, patients can appropriately apply an oral ulcer spray. This can effectively help heal the ulcerated area and alleviate uncomfortable symptoms. Patients should also be sure to drink plenty of water.