The use of erythromycin ointment after an ulcer at the corner of the mouth is useful. When ulcers appear at the corners of the mouth, consider the possibility of orofacial labyrinthitis. It may be caused by local irritation, lack of trace elements, protein or local infection. Treatment is mainly to actively remove the causative factors, while maintaining oral hygiene and strengthening nutrition. If it is caused by bacterial infection, erythromycin ointment can be given topically, and neomycin ointment can also be given topically. If it is caused by fungal infection, it can be accompanied by topical application of 2% clotrimazole cream. After the appearance of corneal lip infection, it is better to take some oral vitamin B and riboflavin to avoid the deficiency of the above elements. It is also necessary to avoid local irritation and choose a toothpaste that does not contain fluoride. If it is caused by allergy to dental materials, you also need to pay attention to timely replacement of materials.