Common causes of red bumps on the back of the neck include bacterial folliculitis, neurodermatitis, and insect bite dermatitis. 1. Bacterial folliculitis:This disease is mainly caused by bacterial infection of the hair follicles at the back of the neck, and the lesions show symptoms such as red, congested papules, papular pustules, and crusts. 2. Neurodermatitis: the cause of this disease is not clear, may be associated with the neck skin contact with chemical fibers, hot and cold stimulation, or the presence of autoimmune diseases, diabetes and other diseases caused by the performance of local erythema, red papules, hypertrophy, itching and other symptoms. 3. Insect bite dermatitis: this disease can be caused by mites, mosquitoes, midges, bedbugs and other insect bites, manifested in the skin localized pinpoint bite marks, conscious itching, red papules, papules and other symptoms. It is recommended that patients go to the dermatology department of regular hospitals in a timely manner, follow the doctor’s instructions to clarify the diagnosis, reasonable treatment, to avoid delaying the condition.