Egg white is the most frequent cause of egg allergy. Egg white contains about 20 allergens, the most important being ovalbumin, ovotransferrin, and ovomucoid. The latter is heat resistant. Other egg allergens that have been isolated are lysozymes. There is evidence that some cross-reactivity exists between the allergens of the egg white and the egg yolk. Egg allergy is most frequently encountered in children (appearing in the first two years of life).