In some patients, chronic recurrent urticaria and angioedema can be due to intolerance to food additives.17 Other causes include drugs, physical factors (cold, pressure, heat, etc.) and foods. However, it should be remembered that no cause can be found in the majority of patients (idiopathic chronic recurrent urticaria). An attempt should be made to identify a cause. If a drug or a food is found to be causative, this should be excluded. In cases where no cause is obvious, the best approach is to treat the condition with the regular use of antihistamine for a period of 6-12 weeks. If the response to antihistamine is not adequate or if symptoms return once antihistamines are discontinued, a trial diet excluding benzoate preservatives, azodyes and salicylate may be helpful. If the condition improves, an open or double-blind challenge may be warranted to confirm the causative relationship. If positive, the diet should be continued for a longer period until spontaneous remission occurs. If the condition does not improve or the challenge does not confirm an association, the diet should be discontinued.
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