Hazelnut allergy

Definition - what is a hazelnut allergy?

A hazelnut allergy is an intolerance reaction in the body that is triggered by hazelnuts. In the case of allergies, contact with hazelnuts typically leads to an excessive reaction of the immune system, which causes the allergic reaction. In most cases, a hazelnut allergy is triggered by the consumption of hazelnuts. Many people are allergic to raw hazelnuts, but cooked or baked hazelnuts are much less likely to have hazelnut allergies.

Hazelnut allergy is an allergy of the so-called immediate type, which can lead to severe reactions and even life-threatening allergic shock.

Read more on the subject at: Allergic reaction


Why an allergy develops is often still unclear. Genetics play an important role in the development of allergies. Children of allergy sufferers are often allergic to many substances themselves. A hazelnut allergy is one of the most common allergies. It often occurs together with other allergies, for example to fruits, pollen, mites (house dust) and animals. In addition, many allergy sufferers are also affected by atopic dermatitis (neurodermatitis).

Also read: House dust allergy and Pet hair allergy

A hazelnut allergy is a type I allergy. First there is initial contact with the allergen, in this case the hazelnut. There are no symptoms at this initial contact. Instead, mechanisms that have not been fully clarified trigger sensitization. This sensitization is mediated by various immune cells. The hazelnut allergen binds to so-called B-cell receptors. In the course of this sensitization, the body learns to perceive the hazelnut allergen as a dangerous substance. As a result, when the hazelnut comes into contact again, an immediate reaction occurs.

Only a few seconds to minutes after contact with the hazelnut, the immune system releases so-called IgE antibodies against the hazelnut allergen. This sets off a whole cascade in which inflammatory cells such as mast cells and eosinophil granulocytes are released. There is an anaphylactic reaction with reddening of the skin and the formation of wheals. The release of inflammatory substances such as histamine can trigger pronounced itching. The tissue can also swell.

If the allergen contact was caused by eating the hazelnut, for example, this can cause swelling in the mouth and throat, which can cause severe shortness of breath. The cause of the hazelnut allergy lies in an excessive immune reaction of the body against certain substances of the hazelnut.

Read more on the subject at: Symptoms of an allergy


The diagnosis of a hazelnut allergy is usually made after the second contact with the hazelnut. When a person comes into contact with a hazelnut for the first time, the immune system becomes sensitized to the hazelnut antigen. The second contact leads to an allergic reaction with typical symptoms. In this case, the anamnesis plays an important role in the diagnosis. By questioning the person concerned, it can be determined which substance may have caused the reaction.

An allergy test can then be carried out. Various messenger substances of the immune system can be detected in blood tests, which are typically increased in an allergic reaction. In addition, test procedures such as the prick test are used. Various potential allergens are injected under the skin. Then the skin is observed for some time. In the case of an allergy, the area where the allergen was introduced into the skin becomes reddened and swollen, and a wheal may form.

Read more on the subject at: Allergy diagnostics

I recognize a hazelnut allergy by these symptoms

Hazelnut allergy can manifest itself in many different symptoms. The symptoms range from harmless reddening of the skin and itching to life-threatening narrowing of the airways. Typically, contact with the allergen occurs first. In the case of the hazelnut, it is mostly consumed. Then there are symptoms in the mouth area. It can be itching and reddening of the skin and mucous membranes. In the case of severe allergies, this skin reaction can spread to the whole body. A so-called urticaria with wheals and extensive reddening of the skin can develop there. In the case of pronounced allergic reactions, swelling in the mouth and in the area of ​​the airways can occur. In the worst case, this can cause severe shortness of breath.

As a result of the allergic reaction to the hazelnut, the vessel walls become more permeable for liquid, and the liquid escapes from the vessels into the surrounding tissue. As a result, the blood pressure drops, there is fluid retention in the skin and possibly in the lungs, which also causes shortness of breath and a lack of oxygen. In addition, the airways narrow, which increases the difficulty in breathing.
Such a pronounced reaction is called anaphylactic shock. Further symptoms can be the tension of the muscles in the intestinal wall with abdominal pain (often cramp-like) with nausea and vomiting. In addition, the nose often begins to run and the eyes water, as the body is stopped to produce more mucus in the nose and tears.

Read more on the subject at: Symptoms of an allergy


The most important form of therapy consists of avoiding the allergen. Therefore, people with a hazelnut allergy should completely refrain from consuming hazelnuts. Since many people are allergic to raw hazelnuts, but can tolerate heated hazelnuts (for example after cooking or baking), attention must be paid to the processing of the hazelnuts. In the case of mild complaints, wait-and-see therapy, if necessary with additional drug therapy, is useful.

For example, antihistamines can be used against histamine (an inflammatory substance that is released when it comes into contact with the hazelnut). Cetirizine is also effective against allergies. Fenistil can be used against severe itching. Cortisone can also be used in acute therapy for more severe symptoms.

Read more on the subject at: Therapy for an allergy

In the event of severe allergic reactions as a result of a hazelnut allergy, emergency therapy may have to be started. This may include a high dose of cortisone and emergency adrenaline. This is included, for example, in the anaphylaxis emergency kit in the form of the so-called epipene. This can be given directly into the thigh in an emergency and can be life-saving in the acute phase. In the case of anaphylactic shock, an emergency doctor must be called who can ventilate the affected person with oxygen if necessary or who can keep the airways open with intubation.

Read more on the subject at: Allergy emergency kit

Duration / forecast

Hazelnut allergy is a permanent disease. So you have to refrain from eating allergy-causing hazelnuts for your entire life. The prognosis is based on how well this hazelnut abstinence is observed. If you refrain from using hazelnuts permanently, you should not expect any restrictions. However, in the case of severe allergies, consumption (including accidental consumption) can lead to life-threatening allergic reactions up to anaphylactic shock. A good education as well as the possession and consistent carrying of an emergency kit are therefore possibly vital for severe allergy sufferers and can significantly determine the prognosis.

Course of disease

The course of the disease can be very different depending on the severity of the hazelnut allergy. In the case of allergies such as hazelnut allergy, the first allergic reaction occurs only after the second contact with the allergen. The allergic reaction can take various courses, from itching in the mouth that lasts for a few minutes to life-threatening anaphylactic shock.

A hazelnut allergy often doesn't change that much over the course of life. People who suffer from a pronounced hazelnut allergy should absolutely refrain from consuming hazelnuts for their entire life. People who are only slightly affected by hazelnut allergy may experience that the allergy grows together in the course of their lives.

Others become more and more sensitive to the allergen in the long run and at some point have to do without hazelnuts permanently. However, those who are allergic to hazelnuts can develop so-called cross allergies. People who are allergic to hazelnuts are often allergic to other substances such as pollen and fruits (cherry, apple, etc.) or develop further allergies in the course of their lives.

How contagious is that?

A hazelnut is based on an excessive reaction of the body's own immune system and is not contagious. So it cannot be transferred to other people. However, the tendency to allergies is often genetically inherited, so that familial clusters of hazelnut allergies can occur. However, it is not a disease that infects children with allergies. Rather, the genetic tendency is passed on from the parents to the children, so that they too develop a hazelnut allergy.