Modalités De L'enquête Alimentaire Dans L'urticaire Chronique

True food allergy or food intolerance appear to be a relatively rare cause of chronic urticaria (3 or 4 % for these two causes combined) and the same applies to intolerance to additives (about 3 %). On the other hand, an aggravating food factor appears to be fairly frequent in approximately one half of cases. The clinical interview and dietary survey investigate the predisposing factors or suggest the possibility of food intolerance or food allergy. Prick-rests to foods are useful to identify allergies mediated by IgE. However, false-negatives can occur in response to commercial extracts, particularly because of the poor standardization of certain allergens, hence the value of prick-tests with fresh foods. False-positive reactions (dermographism) can also be observed, which emphasizes the importance of performing negative control prick-tests. Assay of specific IgE is an alternative to prick-tests, but their prescription in France is subject to certain rules. The problem of the quality of the allergenic material is similar to that of commercial extracts used for prick-tests. Hypoallergenic diets appear to be useful, particularly in certain cases of severe chronic urticaria, with daily episodes, refractory to antihistaminics, in order to detect a possible food intolerance which would have been missed by other methods of investigation. Provocation tests are the << gold standard >> in the English language literature, but are fairly complicated to perform. The responsibility of additives must be investigated by food survey and also possibly by the use of diets without additives.