Acne on the back should be considered to be related to diseases such as folliculitis, Malassezia folliculitis or acne. 1. Folliculitis: After the skin on the back is invaded by bacteria such as staphylococcus and streptococcus, purulent inflammation can be formed at the mouth of the hair follicle, with red follicular papules appearing and pustules forming a few days later, which rupture into yellow scabs and fall off, leaving no scar. 2. Malassezia folliculitis: Long-term use of glucocorticoids or broad-spectrum antibiotics and other factors can induce a large number of Malassezia follicles, leading to follicular occlusion and sebum retention, pimples, papules or pustules appear on the back, chest and other places, and can be extruded powdery sebum-like material. 3. Acne: It is related to the large secretion of sebum, keratinization of sebaceous gland ducts, and the propagation of Propionibacterium acnes, etc. It is mostly found on the cheeks of young men and women, but also on the chest, back, and shoulders, and includes various types of lesions such as pimples, inflammatory papules, pustules, and so on. It is recommended that people with acne on the back go to the hospital in time to clarify the cause and follow the doctor’s instructions to standardize the use of medication.