Itchy back of the hands, small bumps when scratching, this condition may generally be formed by localized allergies. Due to local allergy, after scratching, it may cause local skin irritation, thus inducing the mast cells below the skin tissue to appear degranulation reaction, and the degranulation reaction of histamine, leukotriene and other stimulation of the capillaries inside the surrounding skin tissue, thus causing certain limited edema and the formation of small bumps. Such bumps are actually inflammatory papules, and in severe cases, papules may occur, and even blisters and vesicles may appear. Therefore, if this situation occurs, it is also necessary to actively carry out anti-allergy treatment, the local can be applied topically such as Dinaid cream, you can also take oral antihistamines to control the development of the disease.