Individuals sensitive to hen's egg have been shown to be allergic to lysozyme produced from hen's egg. Because legislation may permit a manufacturer not to list an ingredient constituting less than a specific percentage of the total product, noodles containing egg may not have egg listed on the ingredient panel. A similar situation may occur when egg white is used to give pretzels, bagels, and other baked goods their shiny appearance. In most products, lecithin is derived from soy, but sometimes it may be egg-derived. A patient allergic to egg should avoid buying fried foods from vendors who use the same frying surface for preparing multiple types of food.
Recent evidence suggests that egg-sensitive children can receive measles immunization safely.
Although rare, avian proteins can induce egg allergy in susceptible individuals. It has been suggested that duck egg be substituted for hen's egg in egg-sensitive individuals. These individuals are able to tolerate cooked chicken. Cheese and cream contain milk protein and should be avoided. Milk contamination of a product is possible if the same manufacturing equipment is used for various products.