Hazelnut Allergy: Symptoms and Treatment

Tree nuts are nuts that grow on trees. They include Brazil nuts, cashews, walnuts, pecans, pistachios, and hazelnuts. Hazelnut allergy is one of the most common tree nut allergies, affecting 0.2% to 0.5% of people in the United States.

This article explains where hazelnuts are found and what kinds of symptoms an allergic reaction can cause. It will also discuss how hazelnut allergy is diagnosed and how you can manage it if you have this allergy.

Where Hazelnuts Are Found

Hazelnuts can grow almost anywhere in the continental United States.

You'll find hazelnuts:

• Packaged by themselves
• In mixed nut snacks
• In cookies and chocolates
• In nut oils
• In confections such as praline
• In chocolate-nut spreads like Nutella
• In Frangelico hazelnut liqueur

Hazelnut Allergy Symptoms

With a hazelnut allergy, symptoms typically occur shortly after or immediately after consuming hazelnuts or foods containing them.

Possible reactions, from least severe to most severe, include:

• Nasal congestion or runny nose
• Wheezing or coughing
• Itching of the mouth, throat, eyes, skin, or any other area
• Hives
• Nausea, abdominal pain, vomiting, or diarrhea
• Difficulty swallowing
• Shortness of breath
• Swelling of lips, tongue, or face (known as angioedema)

Causes and Risk Factors

Tree nut allergies typically start in childhood. People with a family history of allergies are at higher risk of developing a tree nut allergy. Tree nut allergies are also associated with eczema and asthma.

These allergic reactions occur when the body's immune system reacts to the hazelnuts as if they are a harmful substance. This immune response produces the symptoms.

Oral Allergy Syndrome

One type of allergic reaction, oral allergy syndrome (OAS), also called pollen food allergy syndrome, is a form of food allergy in which people who are sensitive to specific types of pollen also react to certain foods that are related to those pollens.

Many people with birch pollen allergies also react to hazelnuts. The pollen from birch trees contains allergens that are similar to substances in hazelnuts, so the body reacts to both.

Symptoms of hazelnut oral allergy syndrome are usually fairly mild and are confined to:

• Tingling
• Itching
  

Occasionally, some people with OAS have more severe reactions that may include:

• Rashes
• Swelling of the lips, tongue, and throat
• Delayed gastrointestinal symptoms (abdominal cramps, diarrhea)

Anaphylaxis is very rare in people with OAS.

Diagnostic Tests

In order to diagnose a hazelnut allergy, an allergist will take a medical history and ask about the timing of your symptoms. They will also ask you if you or your family members have any other allergies.

The allergist will likely perform a skin prick test.

A blood test can detect the presence of immunoglobulin E (IgE), an antibody that binds to allergens and triggers the release of chemicals that cause symptoms.

Interpreting Results

An IgE blood test that detects higher-than-normal levels of IgE indicates an allergy, but it does not identify what the allergen is.

During a skin prick test, a small amount of the allergen found in hazelnuts is applied under the surface of your skin. If you develop hives (also called wheals) or another reaction, this could indicate an allergy to hazelnuts. A skin test reaction of 3 mm wheal (hive) larger than the negative control is considered to be positive, which means that you are probably allergic to the substance that was injected. The size of the skin test reaction does not correlate with the severity of the clinical reaction

If those tests are inconclusive, your allergist may recommend an oral food challenge. During this test, you would eat tiny amounts of the food in increasing doses over a period of time. This must be done under supervision in an allergist's office because there's a risk of a severe reaction.

Treating Hazelnut Allergy

Symptoms of OAS may be treated with an over-the-counter antihistamine such as Benadryl.

There is no cure for hazelnut allergy. The only way to avoid a reaction is to avoid eating hazelnuts.

Nuts are one of the eight most common food allergies in the United States and are covered by current food allergy labeling laws. Food manufacturers are required to list nuts on their ingredient labels in plain English. That makes nuts fairly easy to avoid in packaged foods.

A hazelnut allergy warning on an ingredient label should look like this: "Contains Nuts (hazelnuts)."

Summary

Hazelnut allergy is one of the most common tree nut allergies. This nut is commonly used in cookies, chocolates, and pastries.

With oral allergy syndrome, which causes people who are allergic to pollen to react to other substances (like hazelnuts), reactions are typically mild. However, for people who are specifically highly sensitive to the allergen in hazelnuts, there is a risk of more severe reactions, including anaphylaxis, which is a medical emergency. An allergist can perform a variety of tests to confirm a diagnosis of hazelnut allergy.

A Word From Verywell

Hazelnuts are an ingredient in many foods and desserts. Talk to your healthcare provider or allergist if you notice any symptoms after eating or touching hazelnuts. You may need allergy testing to determine whether you are allergic to hazelnuts and also whether you have allergies to other nuts.

When ordering food in a restaurant, stay safe by informing your server or asking to speak to the chef about your hazelnut allergy.