Erythromycin ointment can be used to apply pimples in case of secondary infection. Pimples, also known as acne, is a relatively common chronic inflammatory disease of the sebaceous glands of the hair follicles in dermatology, which occurs mainly on the cheeks, forehead, and jaw, but may also occur on the torso and other places where sebaceous glands secrete abundantly. The cause of acne is mainly related to androgen levels. When there is an increase in the level of androgen in the body, sebaceous glands will secrete a lot of oil, which tends to clog pores, thus causing acne. Not only that, it has a lot to do with the overpopulation of Propionibacterium acnes and the abnormal keratinization of the cells around the hair follicles. For acne diseases, erythromycin ointment is not used as the first line of medication. Usually, it can be used in conjunction with the doctor’s choice of retinoic acid cream, etc., to regulate epidermal keratinization and anti-inflammation. In the secondary bacterial infection, only need to choose erythromycin ointment and other application treatment. It is recommended that patients should combine their acne with their own conditions and use medication as prescribed by their doctors, rather than blindly using their own medication to avoid adverse effects.