CBBC
CBBC Newsround
Pistachio nuts An allergy is when someone's body reacts badly to a food or substance that is harmless to other people.
People can be allergic to lots of different foods for lots of different reasons.
Children are more likely to be allergic to things than adults.
Some of the more common foods to be allergic to are nuts, seafood, milk and wheat. People can also be allergic to certain chemicals in foods.
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