Role of nonallergic hypersensitivity reactions in children with chronic urticaria

Background IgE-independent (pseudoallergic) reactions to food and food ingr edients are common in a subgroup of adult patients with chronic urticaria, who have daily spontaneous occurrence of wheals. However, for children with chronic urticaria (duration longer than 6 weeks, no physical influence), n o data on the importance of pseudoallergen-induced chronic urticaria are av ailable. Therefore, we investigated the role of nonallergic hypersensitivit y to food in all children seen with chronic continuous urticaria in our two clinics over the last 2 years (n=16). Methods All patients were given a low-pseudoallergen diet for 3 weeks follo wed by provocation with food rich in pseudoallergens. To identify the main eliciting agents, a subgroup of responders was exposed to food additives by double-blind, placebo-controlled food challenges. Results Pseudoallergen-induced urticaria was diagnosed in 12 cases (75%). R eactions occurred mainly to coloring agents and preservatives, but also to monosodium glutamate and a sweetener (saccharin/cyclamate). Conclusions These results confirm that nonallergic hypersensitivity reactio ns play a role in children with chronic urticaria,although the latter disea se is rare at that age. In children, food additives; especially coloring ag ents and preservatives, appear to play a more important role in eliciting n onallergic hypersensitivity reactions than in adult patients, where natural ly occurring pseudoallergens in fruits and vegetables are mainly responsibl e.