Erythromycin ointment should not be applied for more than 1 month in general, but the specific situation needs to depend on the condition. Erythromycin ointment itself belongs to the macrolide class of antibiotics, whose main components are erythromycin, petroleum jelly, and paraffin, and is mainly used for skin abrasions, local redness, and other symptoms. However, it is not recommended for infected exudative lesions, which may instead lead to aggravation of the infection. Also, erythromycin ointment should not be used for a long period of time. Some patients have good results when they first start using it, but with increased frequency of use, drug resistance can occur after long-term use. Therefore, it is recommended that the maximum duration of erythromycin ointment use should not exceed 1 month. If no effect is seen after 3 days of applying erythromycin ointment to control local skin infection, it is recommended to take treatment at a regular hospital. In addition, if the patient is allergic to the ingredients of erythromycin ointment and develops local itching, redness and swelling, stop the drug immediately and go to the hospital.