Pimples on the back can be caused by acne or folliculitis. 1. Acne: Acne is commonly found on the face, chest, and back, with papules, pimples, and pustules appearing on the patient’s skin. Its pathogenesis is related to endocrine, bacterial infection and inflammation. 2. Folliculitis: Folliculitis may appear in any hairy area, such as the head and face, neck and shoulders, chest and back, etc., mostly with red papules, papules and pustules as the main manifestation. Its causes are mostly related to germs infecting the hair follicles, and factors such as decreased immunity, obesity, and hair pulling may also trigger the disease. The causes of back acne are not one and the same, and patients are advised to go to regular hospitals to clarify the causes.