Small bumps on the back of the hand and arm may be caused by eczema, urticaria and so on. Generally according to the cause of the symptomatic treatment, the main choice of topical drugs and antihistamines. 1. Eczema: should get rid of the triggers. Hydrocortisone cream and other glucocorticoid cream can be used externally. Those with much exudation can use 3% boric acid solution, 0.1% ethacridine solution and other cold wet compresses. When itching is obvious, antihistamine drugs such as loratadine can be taken orally. 2. Urticaria: avoid contact with allergens. Preferred sedative effect of the second generation of H1 receptor antagonists such as loratadine for treatment. Vitamin C and calcium can reduce vascular permeability, and antihistamines have a synergistic effect. Topical glycerite lotion can be used to stop the itching. If small bumps on the back of the hand and arm itch, do not use your own medicine, you need to see a doctor as soon as possible to avoid serious complications.