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We recently observed a comparable patient who initially presented with NSAID hypersensitivity, developed chronic urticaria 4 years later and eventually lost both conditions after eradication of the intestinal protozoan Blastocystis hominis. 3 ASA hypersensitivity preceding the development of chronic urticaria has been reported by others, but a possible association of these conditions with infectious triggers was not assessed. 4 In some food-allergic patients, systemic immediate type reactions develop only when they are exposed to the respective allergen and concomitantly to ASA. 5 It can be speculated that here the allergic reaction is enhanced by pharmacologic actions of the NSAID (e.g. by an increase of intestinal antigen absorption or by facilitated mediator release). Transferring this to our patient, NSAIDs might have enhanced a subthreshold reaction to antigens from H. pylori, thus leading to clinical symptoms.

A 39-year-old female patient presented with an intense allergic reaction and shock after ingesting sunflower seeds and simultaneously acetylsalicylic acid (ASA). Skin tests and CAP specific. IgE demonstrated an IgE-mediated sensibilization to sunflower seeds. When sunflower seeds were eaten alone, only discrete paresthesia of the oral mucosa occurred. Surprisingly, an oral challenge with ASA was well tolerated. The supplementary contribution of ASA to the allergic reaction was dose-dependent. The quantity of the allergen also modified the intensity of the symptoms. This surprising effect of ASA may be attributed to increased gastric resorption of the allergens. During the course of this reaction, eosinophil-cationic-protein was released.

Of a total of 131 patients suffering from chronic urticaria, 15 were cautiously re-exposed to ASA after an initial provocative exposure during an urticaria test programme 2-11 years before. Only 1 of these patients, who had undergone the initial provocative test 7 years earlier, reacted at the same intensity; 1 other patient reacted with much less intense symptoms 4 years after the original test. Among 3 other patients, who merely reacted to ASA intake with urticarial eruptions and did not suffer from chronic urticaria, only 1 presented 4 years after the initial exposure with oedema of the skin and itching. The tolerance threshold was markedly higher. These results suggest that the sensitivity to intolerance-inducing agents is reduced relatively quickly and may subside completely in most cases.

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