Nuts, seeds and legumesf17

Hazelnut allergy

Hazelnut allergy is one of the most common nut allergies in Europe. In adults with birch allergy it is usually due to cross-reactivity that causes an itchy mouth, but it can also cause severe reactions.

Allergen
Hazelnut Corylus avellana
Allergen code
f17
Key allergens
Cor a 1, Cor a 9, Cor a 14
Included in
1 test
Contents
  1. What is hazelnut allergy?
  2. Symptoms
  3. Where hazelnut is found
  4. Cross-reactivity
  5. How to get tested
  6. Frequently asked questions

What is hazelnut allergy?

There are two types of hazelnut allergy. The most common in adults in northern and central Europe is linked to birch allergy. The protein Cor a 1 in hazelnut resembles Bet v 1 in birch pollen, and it usually causes itching and tingling in the mouth when the nuts are eaten raw. Many people tolerate roasted nuts better.

The other type is caused by IgE to the storage proteins in hazelnut, such as Cor a 9 and Cor a 14. They withstand heat and can cause severe reactions, even from small amounts. This type more often starts in childhood.

Symptoms

  • Itching and tingling in the mouth and throat
  • Swelling of the lips, tongue or throat
  • Hives and stomach problems
  • Breathing difficulties and, in rare cases, anaphylaxis

Where hazelnut is found

Hazelnuts are found in nougat, chocolate spread, pralines, muesli, biscuits, ice cream and liqueurs. Nuts are among the allergens that must always be declared on the ingredients list. "May contain traces of nuts", on the other hand, is a voluntary warning.

Cross-reactivity

Besides the link with birch and hazel pollen, some people with hazelnut allergy also react to other nuts and to peanut. Which nuts you tolerate is individual.

How to get tested

Hazelnut (allergen code f17) is included in our Nut allergy test, together with peanut. The test shows whether you have IgE antibodies to hazelnut. It does not distinguish between the two types of allergy, so if you have had severe symptoms, the allergy should be investigated by a doctor.

Frequently asked questions

Why can I eat roasted hazelnuts but not raw ones?

Cor a 1, which causes the birch-related allergy, is destroyed by heat. Roasted nuts therefore often cause fewer symptoms. This does not apply to the storage proteins.

Can a mild nut allergy get worse?

The birch-related allergy usually stays mild, but symptoms can increase during the pollen season. If you get swelling in the throat or breathing difficulties, seek medical help.

Often cross-reacts with

This text is general information and does not replace an assessment by a healthcare professional. In an emergency, call 112. If you have questions about your health, contact your doctor.

Tests for hazelnut allergy

You take the sample yourself at home. The tests measure IgE antibodies in a capillary blood sample.

Nuts, seeds and legumes

Peanut, hazelnut, sesame, soy and mustard are among the 14 allergens that must always be declared on the ingredients list. In adults with birch allergy, reactions are often due to cross-reactivity.

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