Red bumps all over the back may be caused by Malassezia folliculitis, hives and other factors. They can be treated with topical and oral medications. 1. Malassezia folliculitis: it is an inflammation of the hair follicles and their surroundings caused by Malassezia bacteria, and is most common on the back of the chest where sebaceous glands are abundant, manifesting as hemispherical follicular papules, tens to hundreds of them, which can be densely distributed. The symptoms can be improved by strengthening the local skin cleaning, light diet, if necessary, can be used topical ketoconazole, miconazole and other drugs. 2. Urticaria: Urticaria belongs to the skin allergic diseases, characterized by wind puffs or angioedema. Clinical manifestations are red round or irregular shaped lumps with uneven surface, mostly accompanied by obvious itching. It can be treated with topical medications such as glycerite lotion plus oral antihistamines such as loratadine. The appearance of a large number of red bumps on the back, you should promptly go to the hospital, improve the relevant examination to clarify the cause of the disease, under the guidance of the doctor symptomatic treatment, avoid unauthorized use of drugs.