Understanding Tree Nut Allergies

Walnut allergy is the most common tree nut allergy
Walnut allergy is the most common tree nut allergy in the US.

Greenlin / Moment / Getty Images

Tree nuts are an important food source worldwide as well as one of the most common food allergies. Approximately one in 20 Americans is allergic to tree nuts. There are a number of different types of tree nuts, and the allergic cross-reactivity between them is high.

However, just because you are allergic to one tree nut does not mean you won't be able to eat another tree nut. The risk varies from person to person.

Symptoms of tree nut allergies are the same as other food allergies, although they tend to be more severe. If allergic to tree nuts, your doctor will advise you to avoid all tree nuts as part of your treatment plan.

Should you eat a tree nut and have an allergic reaction, you may need to use injectable epinephrine and/or an oral antihistamine. Unlike other common food allergies, you are less likely to outgrow a tree nut allergy, especially if you prone to reactions.

Peanuts are different from tree nuts in that they are actually a legume. However, up to 50 percent of people with a peanut allergy will also be allergic to at least one type of tree nut.

Common Allergies

The risk of allergy to tree nuts varies by the type. Though you can ultimately be allergic to any type of tree nut, there are four that are known to trigger symptoms more than others.


Pistachios commonly cause food allergy symptoms and are cross-reactive to cashews and mangoes. Hay fever to the pollen from the Parietaria weed found in Europe appears to predispose to pistachio allergy.


Almonds are the most popular tree nut consumed in the United States and the third most common tree nut allergy. Almonds are commonly used when processing food and are unexpected ingredients in breakfast cereals, granola bars, and baked goods. Having an almond allergy may predispose you to other tree nut allergies, especially pistachio nuts.

Generally speaking, the popularity of a tree nut translates to the incidence of allergy to that nut within a population.


Cashews are the second most common allergy-causing tree nuts. The oil found in the nutshell of the cashew is known to cause contact dermatitis and is related to the oils found in the leaves of poison oak and in the skin of mangoes.

Cashew allergens are similar to palm oil, macadamia nuts, peas, soybeans, and walnuts. If you have a walnut or cashew allergy, you may also experience allergic reactions to these other foods.


Walnuts are the most common type of tree nut allergy, especially English walnuts. If you are allergic to walnut pollen, you may experience symptoms of allergic rhinitis. However, just because you are allergic to walnuts doesn't mean you are allergic to tree nuts.

Walnut allergens are similar to those found in pecans, cashews, Brazil nuts, castor beans, cottonseed, and mustard. If you have a walnut allergy, you will likely experience an allergic reaction to some or all of these foods.

Less Common Allergies

Other tree nuts may cause allergic symptoms, but sometimes they aren't "true" allergies. Oral allergy syndrome (OAS) occurs when q certain food allergen iw similar to an allergen found in tree or grass pollen. As such, they "echo" the true allergy but tend to be less severe.


Pecans are a common food in the southern United States, but less common elsewhere in the world. Approximately one in 10 people with tree nut allergies will have a reaction to pecans. If you have a pecan allergy, you may have a walnut allergy as well, given how similar allergens in the two nuts are.


If you have a latex allergy or an avocado allergy, you may also have a chestnut allergy given the similarity between the allergens found in latex and these foods. Mugwort pollen, apples, and peaches may give you a reaction as well if you are sensitive to chestnuts


Allergy to hazelnut is more common in Europe than in the United States. Hazelnut pollen is a common cause of seasonal hay fever. If you have a hazelnut pollen allergy, you are also at risk for a food allergy to the tree nut itself.

Hazelnuts may cause oral allergy syndrome in people with a birch pollen allergy. Symptoms (including itching, swelling, and burning in the mouth and throat) develop within a few minutes and tend to resolve within 30 minutes to an hour.

If you have a birch pollen allergy, you may experience oral allergy symptoms with eating hazelnuts. If you have a hazelnut allergy, you may also be allergic to coconut, cashews, peanuts, and soybeans, given the similarity between the allergens in these foods.

Uncommon Allergies

Some tree nuts are less commonly associated with allergy, often because they are not commonly or widely consumed within a population.

Brazil Nuts

Brazil nut allergies are not common, which may be due to their lack of popularity in the U.S. Brazil nut allergies may increase in the future since genetically modified soybeans accidentally have proteins similar to those found in Brazil nut allergen. If you are allergic to Brazil nuts, you may also be allergic to walnuts.

Pine Nuts

Pine nuts are a common food in southern Europe, but less common in other parts of the world. If you have a pine pollen allergy, you may be allergic to pine nuts, given that the allergens are similar.

Macadamia Nuts

Macadamia nuts are common in Hawaii and the tropics. There is significant cross-reactivity between the allergens in macadamia nuts and cashews. Therefore, if you are allergic to one, chances are you'll be allergic to the other.


Coconut allergies are rare ​and are only distantly related to other tree nuts. However, the coconut allergen is similar to those found in hazelnuts and walnuts.

Was this page helpful?

Article Sources

  • Roux KH, Teuber SS, Sathe SK. Tree Nut Allergens. Int Arch Allergy Immunol. 2003; 234-244.