Urticaria appears as transient, itchy swelling of the skin (hives), which resolves within 24 hours to appear elsewhere in the body, where they remain again less than 24 hours. In some cases they are accompanied by angioedema (swelling) e.g. of the tongue, mucous membranes, face, etc. Urticaria is classified according to its duration into acute (lesions lasting less than 6 weeks) and chronic (lesions that persist beyond 6 weeks). The causes, mechanisms of the formation of urticaria, prognosis, as well as treatment differ in each case and require a careful approach of each patient.