The baby perianal rot may be the existence of anal fissure, wipe erythromycin ointment is good according to the baby anal fissure etiology decision, if it is infected caused by anal fissure, the use of erythromycin ointment treatment effect is better, if it is a mechanical trauma or anal canal stenosis and other reasons lead to anal fissure, the use of erythromycin ointment is not therapeutic effect. 1. Infection: Infection can lead to anal fissure, this situation using erythromycin ointment treatment effect is better. 2. Mechanical trauma: Mechanical trauma is an injury to the anus caused by hard stools, etc. The use of erythromycin ointment in this case is not effective. In this case, the use of erythromycin ointment does not have a therapeutic effect, you can take oral lactulose and other drugs to soften the stool. 3. Anal canal stenosis: Congenital anal deformity or narrowing of the anal canal due to trauma can lead to the formation of anal fissures. The use of erythromycin ointment in this case has no therapeutic effect and needs to be treated by surgical treatment. Parents should bring their babies to the hospital in time to clarify the cause of the disease and carry out targeted treatment under the guidance of the doctor.