Acne on the forehead and back is considered to be acne and folliculitis, which is mainly related to abnormal androgen levels and infections. 1. Acne: Acne may be related to genetic factors, abnormal androgen levels inducing a large amount of local sebum secretion, follicular sebaceous gland duct keratinization, Propionibacterium acnes reproduction, and inflammatory reactions. Some patients with acne on the chest and back with medication, chemical products, stimulation and other triggering factors, acne is mainly characterized by pimples, papules, pustules, but inflammation is obvious when there can be pain. 2. Folliculitis: Folliculitis is related to bacterial and Malassezia infection of hair follicles, while decreased immunity, long-term topical glucocorticoids or antibiotics, obesity and other triggering factors. Patients will appear localized skin red papules or pustules, which may be accompanied by itching and pain sensation. It is recommended that people who have acne on the chest and back should consult a doctor for examination, and follow the doctor’s instructions to use medication after clarifying the disease, and should not use medication indiscriminately on their own. Pay attention to daily skin cleaning, avoid friction stimulation.