A lot of pimples on the back may be related to acne and folliculitis. 1. Acne: It is related to factors such as elevated androgen secretion level, propagation of Propionibacterium acnes, keratinization of sebaceous gland ducts in hair follicles, and heredity. It is also affected by emotional and dietary factors. In clinical practice, it mainly manifests as pimples, papules, nodules and other damages, with the most common areas being the face, forehead, and back where oil secretion is exuberant. 2. Folliculitis: it is an acute infectious skin disease, the onset of which is mainly related to Staphylococcus aureus, Malassezia and other pathogen infections, and is more likely to be induced by a decline in immunity, trauma and other conditions, mainly manifested as red papules and pimples protruding from the surface of the skin, and other damages. Due to the different diseases, the clinical manifestations will also have some differences, the specific circumstances need to ask the doctor for a face-to-face consultation.