• Allergies

What is a Tree Nut Allergy? Symptoms, Diagnosis, and Precautions to Take

Published: February 19, 2025
Updated: February 19, 2025
4 mins

Tree nuts are one of the nine most common allergens affecting people in the U.S. This particular allergy can be tricky to understand. Unlike other common allergens, children with a tree nut allergy rarely grow out of it.

While having a tree nut allergy may increase your risk of seed and legume allergies, that’s not always the case. Those with tree nut allergies tend to learn how to navigate cooking and eating out with the risk of cross-contamination in mind. 

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What is a Tree Nut Allergy?

Those with a tree nut allergy experience symptoms when consuming foods with tree nut proteins. Their immune systems perceive tree nut proteins as harmful to the body. However, tree nuts can be difficult to avoid entirely because of their frequent use in packaged foods in the U.S.

Having an allergy to one specific tree nut does not mean a person is allergic to all of them. Still, those with an allergy to one kind of tree nut may be more likely to develop other tree nut allergies. For example, those with a cashew allergy are more likely to also be allergic to pistachios, pecans, and walnuts.

There is always a risk of cross-contamination when consuming tree nuts. For this reason, many people who are allergic to one type of tree nut avoid all of them entirely.

The following is a list of common tree nuts people may experience symptoms with:

• Cashews

• Almonds

• Brazil nuts

• Pecans

• Macadamia 

• Pistachios

• Walnuts

• Hazelnuts

What are Common Sources of Tree Nuts?

 Tree nuts are one of nine major allergens in the U.S. The U.S. Food & Drug Administration (FDA) requires that manufacturers identify tree nuts as an allergen when used in food products.

Typically, a food label lists potential allergens right underneath the main ingredients. For example, you may see the phrase “contains tree nuts” in bold. 

Distributors also use phrases like “may contain” or “produced in a facility with tree nuts” if there is a risk of cross-contamination in the packaging process. While an allergic reaction is unlikely in products with minimal traces of tree nuts, it’s still important for people with a tree nut allergy to exercise caution when consuming foods with these warnings.

Tree nuts are a staple ingredient in many popular snacks and condiments. Be sure to double check for tree nuts in the following foods:

• Chocolate

• Cookies

• Cakes

• Ice cream

• Coffee flavorings

• Vegan meat substitutes

• Barbecue sauce

• Nut butters

• Granola bars

Unexpected Sources of Tree Nuts to Avoid

Some products may have a hidden source of tree nuts. When eating out, let restaurant staff know about your allergy to avoid the risk of cross-contamination. It’s also important to carefully read the labels of foods before purchasing them.

Unexpected foods that may have tree nuts include:

• Frozen desserts

• Alcoholic beverages

• Marinades

• Energy bars

Some shampoos, conditioners, lotions, and other cosmetic products may contain tree nuts. This is especially true for products containing shea butter or almond extract in the ingredients. 

Always let your healthcare provider know if you have an allergy as well. Many medications contain tree nuts.

What are Tree Nut Allergy Symptoms?

It’s not uncommon for people to have a severe allergy to tree nuts. Knowing the mild and potentially severe symptoms of an allergic reaction can help you know how to best respond.

Those with a tree nut allergy may experience the following symptoms:

• Nausea

• Vomiting

• Abdominal pain

• Mouth itchiness

• Nasal congestion

• Diarrhea

• Stomach cramps

Seek emergency help if you experience severe symptoms like shortness of breath or anaphylaxis — a life-threatening allergic reaction. 

How is a Tree Nut Allergy Diagnosed?

A healthcare provider may first ask about any family history of tree nut allergy and the overall health history of a person before diagnosis. They may recommend a skin prick or blood test to detect potential allergies. 

To conduct a skin prick test, a healthcare provider places a small amount of allergens on the skin. A skin prick test can detect the presence of the antibody immunoglobulin E, which activates when the immune system detects an allergen. After placing the allergen on the skin, a healthcare provider will observe you for about 10-20 minutes.

If they notice a reaction on the skin, a healthcare provider may determine you have a tree nut allergy. A blood test can detect potential allergies as well. 

If neither test detects an allergen but you still show symptoms, a healthcare provider may recommend an oral food challenge. This consists of ingesting small amounts of the allergen in the presence of a healthcare provider and emergency equipment.

Precautions to Take to Reduce Tree Nut Exposure

The best way to prevent an allergic reaction is to reduce overall exposure to tree nuts. While many allergic reactions are mild, others can be dangerous if not treated right away. Tree nuts are one of the most common causes of fatal allergic reactions. 

When reading nutrition labels, try to be as thorough as possible. Some labels may list artificial nuts as an ingredient. However, tree nuts like walnuts or pecans add flavor to artificial nuts.

In case of emergency, a healthcare provider may recommend carrying an EpiPen (epinephrine injection) for people with a severe tree nut allergy. An EpiPen can help alleviate symptoms before emergency assistance arrives in the event of a severe allergic reaction.

Where Can I Learn More About Food Allergies?

At LifeMD, you can speak with a licensed healthcare provider about what to do if you suspect you have a tree nut allergy. They can give you tips for keeping yourself safe during an allergic reaction and how to avoid accidentally consuming tree nuts.

Book an appointment today to learn more about managing a tree nut allergy.

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