Red bumps all over the body and very itchy, may be related to acute urticaria, drug rash, and contact dermatitis and other factors. 1. Acute urticaria: a skin disease caused by a variety of factors to the expansion of small blood vessels in the skin and the permeability of the formation of a skin disease, in the clinic is mainly manifested in the accompanied by intense itching of the wind, triggered by infections, food, drug allergies, and so on. 2. drug rash: that is, because of taking drugs and an allergic reaction, in the pre-morbid period will be obvious history of drug use, can lead to a large number of skin erythema, papules with itching, severe blisters, skin erosion, exfoliation, the more common easily sensitized to the drug, penicillin, sulfonamide and so on. 3. contact dermatitis: is due to local skin because of contact with sensitizing substances or irritating substances and the inflammatory reaction, the lesion site is generally more limited, but can also be due to the contact area of the whole body onset. For the whole body appeared with itching red bumps, must promptly go to the hospital.