Tree nut allergies are among the most common food allergies, affecting between 0.5 percent and 1 percent of people in the United States. Still, many people misunderstand what tree nuts are and what an allergic reaction to them looks like. If you or your child has a tree nut allergy, you might wonder which nuts, if any, are safe to eat.

In this article, you’ll learn what tree nuts are, what reactions can look like, and which foods to avoid.

What Are Tree Nuts?

Just like the name suggests, tree nuts are nuts that grow on trees. There are many of them, and being allergic to one doesn’t necessarily mean you’re allergic to them all. Around 50 percent of children allergic to one tree nut are allergic to at least one other tree nut.

These aren’t the only tree nuts. Brazil nuts, heartnuts (also known as Japanese walnuts), beech nuts, and chestnuts can also cause reactions. You’ll need to work with an allergist to figure out which type of tree nut causes your allergic reactions and which are safe for you to eat.

Are Peanuts Considered Tree Nuts?

Peanut allergies often come up in discussions about tree nut allergies, but they’re not the same. Unlike tree nuts, peanuts don’t grow on trees (they grow underground), and they belong to a different family of foods called legumes. They’re more closely related to beans and peas than they are to tree nuts.

Still, peanut allergies and tree nut allergies can overlap. Around 40 percent of children with tree nut allergies also have peanut allergies.

Signs of an Allergic Reaction to Tree Nuts

Just like with other food allergies, allergic reactions to tree nuts happen because of an overactive immune system. When you eat a tree nut you’re allergic to, your immune system reacts to specific proteins in the nut as if they were germs that could harm you.

When antibodies in your immune system detect proteins from a tree nut you’re allergic to, a defensive immune reaction is triggered. Reactions can range from mild to severe and cause a variety of symptoms. Any of the following symptoms can appear minutes or hours after you eat a tree nut:

• Skin symptoms — Hives, rash, or itching
• Digestive symptoms — Vomiting, diarrhea, or stomachache
• Swelling — Usually of the lips, mouth, tongue, or airway
• Respiratory symptoms — Wheezing, shortness of breath, or sneezing
• Voice and throat symptoms — Hoarse voice, trouble swallowing, or an itchy throat
• Lightheadedness

When To Call 911

It’s possible for a tree nut allergy to cause a life-threatening allergic reaction called anaphylaxis, even if you’ve only ever had mild reactions in the past. Such severe reactions usually only happen after you eat a tree nut, whereas touching a tree nut might cause a rash at the most.

Anaphylaxis can happen within seconds or minutes of eating a tree nut or something that contains tree nuts. Your body can go into shock. Signs and symptoms of anaphylaxis include:

• A sudden drop in blood pressure
• Swollen and narrowed airways, which make it difficult to breathe
• A weak and rapid heartbeat
• Nausea and vomiting
• Fainting or a loss of consciousness
• A sinking feeling in your chest
• Tingling hands, feet, or lips

If you think a loved one is experiencing anaphylaxis from a tree nut allergy, call 911 immediately, even if it looks like the symptoms are improving. You should also use an epinephrine auto-injector (EpiPen) right away if you have one.

Diagnosing Tree Nut Allergies

To diagnose a tree nut allergy, your doctor or allergist will want to know about your symptoms.

If your doctor thinks you may have a tree nut allergy based on your symptoms, allergy testing can confirm if you have an allergy and which tree nuts cause reactions for you.

Oral Food Challenge Test

During an oral food challenge, you eat small, measured amounts of a suspected tree nut while your allergist watches for a reaction. If no signs of a reaction show up after 15 minutes, they give you another small dose.

Doctors often use oral food challenge tests to confirm a tree nut allergy if past reactions were unclear. They also use this test to see if children have grown out of their allergies. About 10 percent of children with tree nut allergies eventually outgrow them. It’s especially rare for children to outgrow tree nut allergies if they’re allergic to more than one tree nut.

Skin Test

A skin allergy test involves pricking your skin with a needle that has tiny amounts of a possible allergen (a substance that triggers reactions) on it, like a tree nut. Your allergist watches the skin in the area for signs of an allergic reaction and measures any reaction that occurs.

Blood Test

A blood allergy test requires a blood sample. Your allergist tests the blood sample for high amounts of antibodies that indicate a high chance of a food allergy. Specific antibodies in your blood indicate allergies or sensitivities to specific tree nuts.

7 Foods To Avoid

Living with a tree nut allergy means avoiding the tree nut you’re allergic to in its whole form as well as food items that contain it even in trace amounts. Some common food items contain tree nuts you can’t taste or see, so be sure to read the labels on packaged foods and mention your tree nut allergy when ordering at restaurants.

Depending on your specific tree nut allergy or allergies, you may need to avoid the following foods.

1. The Nuts You’re Allergic To

You’ll need to avoid eating any tree nuts that cause allergic reactions. Examples of tree nuts that can cause allergic reactions include:

• Brazil nuts
• Hazelnuts
• Pistachios
• Pine nuts
• Chestnuts
• Walnuts
• Almonds
• Pecans
• Cashews
• Macadamia nuts

Eating tree nuts whole as a snack or crushed as a food topping could cause an allergic reaction, and it’s not always possible to predict if an allergic reaction to a tree nut will be mild or severe.

2. Nut Butters and Spreads

Tree nuts are often blended into nut butters and spreads to jazz up toast or other foods. They can also be baked into breads or cakes.

Some spreads, like almond butter, have their tree nut ingredient in the name. Others, like Nutella, aren’t as obvious. Nutella contains hazelnuts. Similarly, gianduja is a chocolate-hazelnut spread. Be sure to check the ingredients list on any jar of spread. Look for nut paste, nut oil, or nut extract on the list.

3. Certain Liqueurs

You might not expect nuts in beverages, but some alcoholic drinks and liqueurs are made with tree nuts. For example, amaretto liqueur is an Italian almond liqueur. Frangelico, another sweet liqueur, contains hazelnut.

Unlike with food items, food allergen labeling for alcoholic beverages isn’t federally regulated. Therefore, you probably won’t see anything about tree nuts on the label. Instead, you’ll have to call the manufacturer to learn more about ingredients that fall under umbrella terms like “natural flavoring.”

4. Baked Goods Containing Nuts or Nut Flours

Many baked goods are made with tree nuts. Even those that don’t contain whole nuts may be made with finely ground nuts as a flour substitute, like almond flour.

Examples of baked goods that frequently contain tree nuts are:

• Biscotti
• Baklava
• Cookies
• Granola bars
• Pies
• Cakes

Avoid eating baked goods if you can’t confirm whether or not they contain tree nuts you’re allergic to. Bakeries have a high risk for cross-contact between foods, so you might be exposed to trace amounts of a tree nut even if the pastry you’re eating doesn’t contain it.

5. Barbecue Sauce

Another food item that may unexpectedly contain tree nuts is barbecue sauce. As with other food products, always read the label on any sauces and dressings. The ingredients list should tell you about what’s in the product.

6. Pesto

Pesto is a sauce usually made with pine nuts, but it can also be made using walnuts or cashews. Commonly seen in Italian dishes, pesto is typically green in color because basil is one of its other key ingredients.

7. Confections and Candy

Some common candies and confectionery ingredients have tree nuts that may or may not be easily detectable. These include:

• Praline — Candy made using nuts and sugar
• Nougat — A chewy treat made with egg whites, sugar, and nuts
• Marzipan — A paste-like confection made with almond flour, sugar, and sometimes almond extract

Chocolates and candy bars may also contain tree nuts. Sometimes the name of the candy or chocolate clearly states it contains nuts. But certain sweets may have tree nuts in small amounts, so be sure to check the label.

When Unexpected Reactions Occur

Even if you’re extra cautious about eating tree nuts, you might have a reaction because of cross-contamination. Your doctor or allergist can help you prepare for unexpected reactions. They may prescribe food allergy medications to reduce your risk for allergic reactions or prescribe an epinephrine auto-injector to carry with you at all times.

Talk to your healthcare provider about ways to manage tree nut allergies for you or your child.

Join the Conversation

On MyFoodAllergyTeam, people share their experiences with food allergies, get advice, and find support from others who understand.

Do you have any tips to share with other people who have tree nut allergies? Let others know in the comments below.