OBJECTIVE: To determine the most frequent food allergens causing immediate hypersensitivity reactions in Swiss children of different age groups and to investigate the clinical manifestation of IgE-mediated food allergies in young patients.PATIENTS AND METHODS: The study was a prospective analysis of children referred for assessment of immediate type I food hypersensitivity reactions. The diagnostic strategy included a careful history, skin prick tests with commercial extracts and native foods, in vitro determination of specific IgE to food proteins and food challenges when appropriate. A total of 278 food allergies were identified in 151 children with a median age of 1.9 years at diagnosis.RESULTS: Overall, the most frequent food allergens were hen's egg (23.7%), cow's milk (20.1%), peanut (14.0%), hazelnut (10.4%), wheat (6.1%), fish (4.3%), kiwi and soy (2.2% each). In infancy, cow's milk, hen's egg and wheat were the most common allergens. In the second and third year of life however, the top three food allergens were hen's egg, cow's milk and peanut, whereas above the age of 3 years, peanut was number one, followed by hen's egg and fish. Overall, urticaria (59.0%) and angioedema (30.2%) were the most frequent clinical manifestations. Gastrointestinal symptoms were found in 25.9% and respiratory involvement in 25.2%. There were 13 cases (4.7%) of anaphylaxis to peanut, fish, cow's milk, hen's egg, wheat and shrimps.CONCLUSIONS: A total of eight allergens account for 83% of IgE-mediated food allergies in Swiss infants and children, with differences in the distribution and order of the most frequently involved food allergens between paediatric age groups.