cross reactivity
A situation where an allergic reaction to one substance also leads to an allergic reaction to another substance. This is usually because the allergens (e.g. peanuts and tree nuts) possess similar characteristics which trigger the body's immune defences
Cross-reactivity happens when a person’s immune system reacts not only to a specific allergen but also to a similar substance in a different food. For example, someone allergic to birch pollen might also react to apples because the proteins are similar.
EFSA considers cross-reactivity when assessing food allergens. By understanding which allergens can trigger reactions in people sensitive to related proteins, EFSA can provide guidance for labelling, risk assessment, and protecting consumers with food allergies.