Erythromycin ointment applied to a broken wound at the corner of the mouth can play a role in protecting the wound and preventing infection. Erythromycin ointment belongs to the class of macrolide antibiotics, has antibacterial activity against a variety of bacteria, can play a role in inhibiting local bacteria and preventing wound infection. The use of erythromycin ointment should follow the doctor’s instructions, avoid contact with the eyes and mucous membranes of the mouth, nose and other parts of the body, after the use of the drug, such as discomfort (such as burning sensation, itching, rash, redness and swelling, etc.) should be discontinued immediately, and the local medicine will be rinsed clean. Pregnant and lactating women should consult a medical professional before use. If there is no significant improvement in the ulcers after using the drug, the drug should be discontinued and timely medical treatment should be carried out under the guidance of a professional physician.