common tree nut allergies
Tree nut allergies are some of the most common food allergies

Tree nut allergies are some of the most common food allergies, affecting nearly 0.5%-1% of people in the U.S. Examples of tree nuts include:

  • Cashews
  • Pistachios
  • Almonds
  • Brazil nuts
  • Hazelnuts
  • Pecans
  • Walnuts
  • Pine nuts
  • Lychee nuts

The most common nut allergies are cashew, walnut, hazelnut and pistachio. In the U.S. the most common nut allergy is cashew, followed by walnut. In the U.K. the most common nut allergy is hazelnut. Even in smaller quantities, cashew and pistachio allergies can cause severe reactions as compared to other tree nuts.

Surprised that peanuts aren’t mentioned in the list? True, peanut allergy is more common. But  peanuts are legumes, not tree nuts. If you have a peanut allergy, however, it’s likely that you may have a tree nut allergy as well, since peanuts and tree nuts share some structural proteins. In fact, 25%-40% of people with peanut allergies are allergic to one or more tree nuts.

What causes tree nut allergies?

When you have a tree nut allergy and eat a tree nut, proteins in the nut attach to the defense proteins (antibodies) in your immune system. Your body identifies this nut protein as dangerous and triggers the immune system to respond. You then start to develop the signs and symptoms of allergy. Symptoms may range from a mild rash to severe choking. 

Anyone can develop an allergy, but you are at increased risk if one of your family members has a tree nut allergy.

Can you be allergic to some tree nuts and not others?

You can be allergic to one, some or many kinds of tree nuts. 

If you have an allergy to one particular tree nut, you may also be allergic to other types of tree nuts that contain a similar protein. For example, if you are allergic to almonds, you will most likely be allergic to hazelnuts as well. The same is true with walnuts and pecans, as well as pistachios and cashews. Nearly 50% of children who are allergic to one tree nut are allergic to another tree nut as well.

Talk to your doctor if you think you may have a nut allergy, and avoid all tree nuts until your doctor figures out which ones cause allergic reactions in you.

How are tree nut allergies diagnosed?

Since tree nut allergies can be life-threatening, getting a proper diagnosis is important. 

An allergist-immunologist is a type of doctor who specializes in allergies and the immune system. They will take a medical history, ask about any previous allergic reactions you've had and whether you have a family history of allergy. 

They may also conduct the following tests to check what kind of tree nuts you are allergic to:

Skin prick test

The gold standard for allergy testing is a skin prick test. It involves pricking your skin, inserting a small amount of the tree nut onto the skin and waiting to see if there is a reaction. If you’re allergic to the tree nut, the pricked skin will become red and itchy and a bump will form.

Food challenge test

If the skin prick test does not provide a definitive diagnosis of a tree nut allergy, your doctor may order a food challenge test. In this test, you will be asked to eat only the tree nut in question, mixed with other food or in the form of capsules, in increasing amounts over several days. Your doctor will supervise the test and ask you whether you have experienced any allergic reaction. You will be instructed to take an emergency injection in case a severe allergy develops.

Blood tests

Your doctor may also conduct blood tests such as complete blood count tests, liver function tests and kidney function tests to determine whether you have other medical conditions.

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Medically Reviewed on 5/26/2021
References
Weinberger T, Sicherer S. Current perspectives on tree nut allergy: a review. J Asthma Allergy. 2018;11:41-51.

Tree nut allergy. https://acaai.org/allergies/types/food-allergies/types-food-allergy/tree-nut-allergy