Egg allergies are pretty common, especially in babies, toddlers and preschool aged kids. Some studies claim that about 66% of kids can outgrow their egg allergy by the time they are 7.
Both the yolks and the whites of eggs are made of proteins that can cause allergic reactions. It is possible for a child to be allergic to the egg yolk and not the white, but the whites cause more reactions than the yolks. In some rare instances egg allergies can develop in someone older.
Most people who are allergic react to the proteins in egg whites, but some can't tolerate proteins in the yolk. Allergic reactions to eggs can occur minutes or hours after eating them. Most reactions only last about 24 hours.
Although it is rare, there is a small percentage of egg allergic people who will have a serious anaphylactic reaction to an egg exposure.
Finally, those allergic to eggs are advised not to get an annual flu shot because the flu shot is cultured with egg ingredients. MMR vaccine also uses eggs, however there is a disagreement among experts as to whether or not the MMR is safe for those with egg allergies. Use your own discretion.
Breaded foods (some)
Caesar salad dressing
Cookies (especially chocolate chip)
Cream fillings in pastries, cookies, bakery goods
Fried foods (can have cross-contamination in a restaurant fryer)
Imitation crab meat
Jelly beans brushed with egg whites
Malted Beverages and Candies
Meat cooked in batter (chicken nuggets, fish sticks, etc...)
Simplesse (fat substitute)
Wine (some brands)
Eggs are in many unexpected foods. They are used as a binder and clarifying agent. Always call the manufacturer when you question whether or not a product is safe to eat. If you are unsure, avoid the food completely.
Egg protein is found in many products that you would not normally expect. Egg whites and shells are used as clarifying agents in soup stocks, wine, alcoholic drinks, coffee drinks, and consommés. Check the labels and when in doubt, avoid the food completely.
Apo Vitellenin (from the egg yolk of a chicken)
Baking powder containing egg white or egg albumin
Imitation egg product
Surimi (used in imitation seafood)
Lecithin (can also come from soy, animal byproducts, corn, and peanuts)