Hazel pollen allergy

What is hazel pollen allergy?

Hazel pollen allergy is a pollen allergy in which the immune system reacts to pollen from hazel shrubs. The most important allergen, Cor a 1, resembles Bet v 1 in birch pollen. That is why it is unusual to be allergic to hazel alone – most people also react to birch and alder.

Symptoms

• Sneezing and a runny or blocked nose
• Itchy and watery eyes
• Itching in the roof of the mouth and the throat
• Coughing or asthma symptoms

Because hazel flowers so early, the symptoms are sometimes mistaken for a cold.

When does hazel flower?

Depending on the climate, hazel usually flowers between January and March, and after a mild winter it can start even earlier. Further north it flowers later, and in the far north of Europe it grows only sparsely.

Hazel, alder and birch flower one after another. People who react to all three can therefore have symptoms for several months.

Cross-reactivity

Cor a 1 is also found in hazelnuts. Many people with pollen allergy to hazel and birch therefore get an itchy mouth from hazelnuts and from raw fruit such as apple. The reactions are usually mild. Nut allergy can also be caused by other proteins that trigger stronger reactions – if you have had severe symptoms from nuts, talk to your doctor.

How to get tested

Hazel (allergen code t4) is included in our Pollen allergy test, together with birch, alder, timothy grass and mugwort. The test shows whether you have IgE antibodies to hazel pollen and can be taken at any time of year.

Frequently asked questions

Can I be allergic to hazel but not to birch?

It happens, but it is unusual. Most people who have IgE to hazel also have it to birch, because the allergens are so similar. That is why it is useful to test pollen from several trees at the same time.

Why do I get pollen symptoms as early as February?

At that time of year it is usually hazel or alder that is flowering. In many parts of Europe, the first pollen arrives in February or even earlier, long before birch.