Red pimples on the body may be caused by folliculitis, contact dermatitis or insect bite dermatitis. 1. Folliculitis: folliculitis is a kind of inflammatory skin disease with hair follicle involvement as the main manifestation, mainly due to bacteria, viruses and other pathogens infected hair follicles, causing inflammatory reaction of the hair follicles, there will be localized red, swollen, painful symptoms, some patients will be manifested as a red pimple, and some will be pus and ulceration, so the body with a long red pimple considerations may be caused by folliculitis. 2. Contact dermatitis: contact dermatitis is due to external allergens into the body, stimulation of the skin caused by abnormal immune disease, mainly manifested in various types of rashes, may appear erythema, papules, blisters and other lesions. 3. Insect bite dermatitis: insect bite dermatitis is due to the human body by insect bites, resulting in insect secretions invade the human body caused by skin allergic reactions, the affected area is usually manifested as redness, erythema, blisters, and red papules and other lesions phenomena, so the body grows red acne may also be caused by insect bite dermatitis. Because of the causes of red acne on the body more reasons, so when the patient appears related to the discomfort, it is recommended to go to the hospital in a timely manner for examination and diagnosis, clear cause of the disease in the doctor’s guidance combined with the personal situation of targeted treatment, to avoid delays in aggravation of the symptoms.