There are many causes of ulcers at the corners of the mouth, such as infectious factors, contact factors, nutritional deficiencies, etc. After diagnosis, you can choose general treatment or medication. 1. Infectious factors: the corners of the mouth suffer from bacterial and viral infections, which can cause ulcers at the corners of the mouth. For bacterial infections, erythromycin ointment and mupirocin ointment can be used externally; for viral infections, acyclovir cream and ganciclovir cream can be used externally as prescribed by the doctor. 2. Contact factors: the corners of the mouth come into contact with toxic substances, allergic foods, can also cause the phenomenon of mouth ulcers. Treatment needs to avoid allergens, while with loratadine, cetirizine and other anti-allergy drugs, while with fusidic acid cream for external use. 3. Malnutrition: lack of vitamins, trace elements and other substances in the body can also cause ulcers at the corners of the mouth, should pay attention to enhance nutrition, not picky or partial food. There are many reasons for mouth ulcers, after the symptoms, it is recommended to go to the hospital in a timely manner to improve the examination, follow the doctor’s instructions to choose the appropriate medication, do not use drugs indiscriminately, so as not to lead to adverse consequences.