[Chronic urticaria--still a vexing problem? Progress in diagnosis and therapy].

Despite the suggestion than an intolerance reaction could be a possible cause of chronic urticaria in some cases, the pathogenesis of this disease remains enigmatic. It is unlikely that an intolerance reaction to substances used in provocation testing is the cause of the daily rashes. It rather seems that the intolerance reaction is an indication of a certain instability of the mast cell membrane of other factors of the reaction cascade leading to the wheals. Fortunately, an effective symptomatic therapy is available in such cases where the cause cannot be detected and the trigger cannot be avoided. The modern, non-sedating H1-antihistamines have been tested in clinical-experimental studies as well as in a multicentric study in patients with chronic urticaria. In histamine-induced wheals, terfenadine was slightly superior to other non-sedating H1-blockers, when the grade of reduction of wheals and flare areas was taken as criterion. In clinical studies, another antihistamine, loratadine, was slightly, but statistically not significantly superior to terfenadine. In cases that cannot be effectively treated with H1-blockers alone, the additional administration of non-steroidal antiphlogistics (acetylsalicylic acid, indomethacin) is recommended. To avoid aggravation of the symptoms caused by the antiphlogistics, the drugs must be given in increasing dosages and after concurrent treatment with H1-blockers. With this combined therapy, about 50% of the patients present amelioration.