A person with food allergies reacts every time he eats, touches or breathes in the allergy-causing food. Someone may be allergic only to one type of food, have multiple allergies or react to foods with similar characteristics as the food he is allergic to, notes the National Institute of Allergy and Infectious Diseases. People can be allergic to any kind of food, but certain foods cause allergic reactions more often in children and adults.

Milk

Milk allergy is common in children, but most outgrow the allergy by age 5 years, according to the American Academy of Allergy Asthma & Immunology. The allergy-causing substances in milk are casein and whey, so all foods that label these in their ingredient list may trigger an allergic reaction. Examples include infant milk formula, butter, cream, nougat, custard, cheese, pudding and many baked goods. Children with milk allergy will also react to sheep's or goat's milk, and some will react to beef.

Peanuts and Nuts

Peanut and nut allergies are life-long and can occur at any age. Nuts can also cause anaphylaxis, a rapid and potentially deadly allergic reaction, from even tiny amounts eaten or inhaled. Examples of nuts that trigger allergic reactions include walnuts, cashews, brazil nuts and pistachios. Doctors recommend that people with peanut or nut allergy should completely avoid all nuts and peanuts because they hare similar allergy-causing proteins, according to the AAAAI.

Seafood

Shellfish and fish allergies are more common in adults, and potentially severe. The types of shellfish that trigger allergies include crustaceans -- shrimp, lobster, crayfish and crabs, and mollusks -- oyster, squid, abalone and clams. People usually have multiple shellfish allergies, or multiple fish allergies, but those who are allergic to fish are not necessarily allergic to shellfish, and vice versa, notes the AAAAI.

Egg

Egg allergy is common among children, but according to MayoClinic.com, most will tolerate it by age 5. Examples of food containing egg include eggnog, egg substitutes, mayonnaise, meringue, baked goods and bread baked with shiny glaze, noodles, pasta, salad dressing, frostings and processed meats. Accidental exposure to egg is possible because many foods contain allergy-causing egg proteins such as albumin, globulin, lecithin, ovalbumin, lysozyme and Simplesse.