Erythromycin is a macrolide antibacterial drug, the mechanism of action is to inhibit the synthesis of bacterial proteins. Erythromycin ointment is a topical antimicrobial ointment containing 10 mg of erythromycin per gram, supplemented with yellow petroleum jelly. The antibacterial spectrum of erythromycin is similar to that of penicillin, and it has a strong inhibitory effect on Staphylococcus spp, Streptococcus pyogenes, Streptococcus pyogenes and most Gram-positive bacilli and some atypical pathogenic bacteria such as Mycoplasma and Chlamydia. Yellow petroleum jelly is a commonly used ointment base with some moisturizing effect. Erythromycin ointment is mainly to be used clinically for the treatment of purulent skin diseases such as impetigo, small burns, infections of ulcerated surfaces and common acne. The common feature of these diseases is localized bacterial infection. The use of erythromycin ointment has two effects: the antibacterial effect of erythromycin and the moistening effect of petroleum jelly. However, it is important to note that for bacterial infections, this product does not work on skin conditions caused by fungal infections, such as ringworm of the head, ringworm of the nail, ringworm of the femur, and ringworm of the hands and feet. Clinically, there are patients with rhinitis using erythromycin ointment, which mainly uses the moisturizing effect of yellow petroleum jelly in erythromycin ointment to moisten the nasal cavity and facilitate the shedding of dry nasal crusts, not the antibacterial effect of erythromycin.