Bumps on the back can be caused by acne, folliculitis, hives and other diseases. 1. Acne: Acne, also known as pimples, is a common chronic inflammatory skin disease in dermatology that occurs during puberty. Acne tends to occur on the face and neck, chest and back, shoulders and so on. It can be mild or severe, resulting in localized pimples, inflammatory papules, and in severe cases, pustules, cysts, and nodules may form. 2. Folliculitis: Folliculitis is caused by bacterial infection, which may lead to localized single or multiple red papules, and can occur in any part of the body where there are hair follicles, such as the head, face, chest, back, buttocks, vulva and so on. 3. Urticaria: Urticaria is a limited edema reaction, related to allergy, common causes include food, infection, drugs, respiratory inhalants and skin contacts. Physical factors, mental and endocrine factors and genetic factors can also lead to the occurrence of urticaria. It can lead to the appearance of windy, red, itchy bumps of varying sizes in various parts of the body. In addition to this, sebaceous cysts, lipomas, etc., may also lead to the appearance of bumps on the back. It is recommended not to deal with them blindly, but to visit the dermatology department of the hospital to clarify the cause before treatment.