An allergic reaction to food is a mistaken attack by the body's immune system against a substance that other people find harmless.
Food allergies are more common in children than adults.
Causes Just about any food can be the source of an allergic reaction. However, the most common culprits are cow's milk, eggs, wheat, soybeans, peanuts, fish, chocolate, shellfish and tree nuts such as walnuts or pecans. You are at higher risk if you have a family history of food allergies. A mild reaction may produce diarrhea, stomach pain, gas, or a full feeling in your stomach. You may develop a skin rash with hives and itching.