ABSTRACT
Acute urticaria is defined by a spontaneous appearance of wheals, possibly accompanied by angioedema, for a duration of no more than 6 weeks (1). Acute urticaria must be differentiated from acute attacks of physical urticaria, special defined types of urticaria, or other diseases related to urticaria (e.g., urticaria pigmentosa) in which whealing may also occur. There is no consensus in the international literature about the minimum duration of acute urticaria. This is of special importance since the term acute urticaria is used by most dermatologists to describe a disease entity clearly differentiated from the short occurrence of wheals (less than a few hours) as an accompanying symptom of other diseases or anaphylactic reactions. According to the consensus of the German Dermatological Society, a short appearance of wheals in a patient with anaphylaxis would be called an urticarial reaction, but not urticaria (2). This stands in clear contrast to the disease termed acute urticaria, in which whealing generally lasts for a few days at least. To many this distinction may appear semantic, but it has particular relevance for the interpretation of data regarding the epidemiology and causes of acute urticaria.
