Seborrheic dermatitis is a chronic, recurrent, inflammatory skin disease that commonly affects seborrheic areas such as the head, face, chest and back. Erythromycin or metronidazole is usually not used for seborrheic dermatitis alone, but can be chosen if there is a co-infection. Seborrheic dermatitis is a chronic inflammatory skin disease that occurs at the site of seborrhea. If it is simple seborrheic dermatitis and there is no co-infection, you don’t need to use antibiotic drugs such as erythromycin or metronidazole. You can choose glucocorticoid drug treatment, such as hydrocortisone cream, dexamethasone cream, not suitable for hormone drugs can be used with calcium-modulated phosphatase inhibitors, such as tacrolimus ointment, pimecrolimus cream. Seborrheic dermatitis can cause itching, if excessive scratching will cause bacterial infection of the skin lesions, then you can choose antibiotic drugs under the guidance of the doctor to apply, if it is anaerobic infection, you can choose metronidazole, if it is gram-positive bacteria and atypical pathogens, etc., you can choose to erythromycin ointment to apply. Patients with seborrheic dermatitis are advised to go to the hospital in time, topical erythromycin and metronidazole may have adverse reactions, it is recommended to use under the guidance of a doctor, avoid self-medication.