What Is a Tree Nut Allergy?
Tree nut allergies are when your body’s immune system overreacts to proteins found in nuts that grow on trees, such as almonds, cashews, and walnuts. Your immune system treats these proteins as a potential threat and tries to fight them off. This response is an allergic reaction.
Even a little bit that you swallow or inhale can bring on a reaction. It’s easy to avoid the nuts themselves. But because they’re also added to a lot of other foods, you may not always be aware of their presence.
Having an allergy to one type of tree nut doesn't mean you're allergic to all of them. But some tree nuts are related, such as cashews and pistachios, and walnuts and pecans. So you may be allergic to more than one tree nut.
For most people, a tree nut allergy starts during childhood and lasts all their life. But about 10% of children with tree nut allergies eventually outgrow them.
Tree nut vs. peanut allergy
A tree nut allergy isn't the same as a peanut allergy. Peanuts grow underground and are classified as legumes, like beans and peas. About 30% of people with a peanut allergy are also allergic to at least one tree nut.
Tree Nut Allergy Symptoms
Tree nut allergy symptoms can be mild or serious, and they're unpredictable. Just because you had a minor reaction last time doesn't mean your allergy symptoms will always be mild.
Signs of a tree nut allergy can include:
- Hives (urticaria), which are raised, itchy bumps on your skin
- Swollen lips
- Skin rash
- Runny or stuffy nose
- Tingling in your mouth or throat, or a tight feeling in your throat
- Stomach pain, nausea, or vomiting
- Diarrhea
- Trouble swallowing
- Itching in your mouth, throat, eyes, skin or other areas
- Shortness of breath
Call your doctor right away if you have any of these after eating any kind of nut.
Tree nut allergy and anaphylaxis symptoms
Tree nuts, along with peanuts and shellfish, are among the foods that most often cause a serious allergic reaction called anaphylaxis. Anaphylaxis interferes with your breathing, sends your body into shock, and can be life-threatening.
Symptoms of anaphylaxis include:
- Difficult or loud breathing
- Wheezing or frequent coughing
- Tightness in your throat or chest
- A swollen tongue
- Trouble swallowing
- Hoarseness or a hard time talking
- Dizziness or fainting
- In very young kids, paleness or floppiness
Anaphylaxis is an emergency. If you or someone you're with has these symptoms, use an epinephrine auto-injector right away, if possible, and call 911.
Tree Nut Allergy Causes
Tiny proteins found in tree nuts aren’t affected by things like heat or acid, so they’re still intact after they’re processed, cooked, or even digested. Some people are sensitive to these proteins, and their bodies make antibodies to fight them.
The nut proteins latch on to the antibodies. This triggers your immune system to release a chemical called histamine. Histamine is what causes the symptoms of an allergic reaction.
Tree nuts include:
- Almonds
- Brazil nuts
- Cashews
- Chestnuts
- Filberts
- Hazelnuts
- Hickory nuts
- Pecans
- Pistachios
- Walnuts
Coconuts also grow in trees, but they're technically fruits, not nuts. Many people with tree nut allergies can safely eat coconut. They may also be able to eat pine nuts and macadamia nuts, which are actually seeds. Talk to your allergist about what's safe for you.
Tree nut allergy risk factors
You may be more likely to be allergic to tree nuts if you:
- Are allergic to peanuts
- Have family members with nut or other allergies
- Had eczema, asthma, or an egg allergy at a young age
Tree Nut Allergy Diagnosis
To diagnose a tree nut allergy, your doctor will start by asking you about your symptoms, health history, and whether others in your family have allergies. They'll also do tests such as:
Skin prick test. A doctor or nurse uses a needle to prick the skin of your arm or back, then applies a small amount of nut protein to the spot. If a rash or raised spot develops, that means you have a nut allergy.
Blood test. This test checks a sample of your blood for a particular antibody (a protein your immune system makes) that signals an allergic reaction.
Oral food challenge. You eat a small amount of nut protein while your doctor monitors you. This takes place in your doctor's office so you can get immediate treatment in case of a reaction.
Living With a Tree Nut Allergy
Living with a tree nut allergy means always being careful about what you eat. Even if you're only allergic to one particular tree nut, your doctor may advise you to avoid all types of tree nuts as well as peanuts. Not only does having an allergy to one nut make you more likely to be allergic to others, but foods containing nuts are often exposed to other types of nuts during processing. This is called cross-contamination.
Foods packaged in the U.S. are required to have labels that say if they contain tree nuts and what type of nuts they contain. But you'll have to ask about foods at most restaurants and at social gatherings to make sure they don't contain allergens. Even if they don't, they may have been made in the same place or with the same equipment as food with nuts, which could cause cross-contamination. Some people carry a "chef card" that explains their allergies to restaurant staff.
People with tree nut allergies should carry two epinephrine auto-injectors with them at all times in case of a serious reaction.
Foods to avoid when you have tree nut allergies
The tree nut allergy list of items to avoid includes:
- Nut butters: Almond, cashew, and others
- Nut pastes. These include products like marzipan, almond paste, and nougat.
- Nut oils, especially unrefined ones
- Nut milks such as cashew and almond milk
- Nut flour
- Tree nut extracts, like almond extract
- Pesto sauce
Common foods with nuts
Check the ingredients before eating these foods, which sometimes contain tree nuts:
- Baked goods: Cookies, candy, pastries, pie crusts, and others
- Candy: Watch out for chocolate candies as well as pralines, nougat, and marzipan
- Other sweets: Ice cream, frozen desserts, puddings, and hot chocolate
- Cereals and granola
- Trail mix
- Grain breads
- High-energy bars
- Crackers
- Honey
- International foods. Nuts are common ingredients in African and Asian cooking (especially Thai and Indian foods), and in Mexican and Mediterranean foods.
- Cold cuts such as mortadella, an Italian ham that may include pistachios
- Veggie burgers
- Sauces. These may include barbeque sauce, hot sauce, pesto, gravy, mole sauce, glazes, or marinades.
- Salads and salad dressing
Other things that can trigger a tree nut allergy
Sometimes, seed nut protein is found in places where you might not expect it, such as:
- Pet foods and treats
- Soaps, lotions, and cosmetics that contain nut oils
- Natural brushes or sponges that contain walnut shells
- Nutritional supplements
- Flavored coffees
- Alcoholic beverages
When your child has a tree nut allergy
If your child has a tree nut allergy:
Teach them to read food labels as soon as they're able.
Teach them to never share food or eat anything they're unsure about.
Pack their lunches and snacks. If they're attending a party or outing, send along some nut-free treats.
Make sure teachers, coaches, and other adults your child spends time with have a copy of your child's allergy action plan (as recommended by your child's allergist). Also make sure these adults can use an epinephrine auto-injector pen.
Talk to school administrators about establishing a nut-free table in the lunchroom.
If you ever prepare foods in your home that contain nuts, thoroughly clean your hands, kitchen equipment, and all surfaces that came into contact with the allergen afterward.
Consider having your child wear medical alert jewelry that displays their allergy information.
Tree Nut Allergy Treatment
For mild allergic reactions, antihistamines may be enough to manage your symptoms.
But anytime you accidentally eat something with nuts in it, you should watch for signs of anaphylaxis. If you have them:
- Lie flat on your back.
- If you have epinephrine, use it. Repeat after 5 to 15 minutes if your symptoms haven’t gotten better.
- Call 911 and get medical help. Do this even if the epinephrine helped your symptoms.
Carry two epinephrine auto-injectors (AUVI-Q, Adrenaclick, EpiPen, Symjepi) with you at all times, and know how to use them.
To reduce your chances of having a serious reaction after an accidental exposure to nuts, your allergist may recommend oral immunotherapy. For this treatment, your doctor gives you tiny amounts of tree nut proteins, gradually increasing the amount over time. This helps to desensitize your immune system. Oral immunotherapy can't stop a reaction or cure nut allergies, but can help bring peace of mind.
A drug called omalizumab (Xolair) can also make serious reactions less likely and protect you from accidental exposure to tree nuts. It does this by binding to the antibodies that cause the symptoms of a reaction. You take it as a shot every 2-4 weeks.
Tree Nut Allergy Prevention
There's some scientific evidence that introducing children to common food allergens at an early age might help protect from developing food allergies.
For years, parents were advised not to give babies nuts, peanuts, dairy, eggs, or fish for fear that these foods would trigger serious allergic reactions. But now experts recommend that young kids be exposed to a wide variety of foods.
Start introducing these foods once your baby is eating solids, around age 4-6 months. Try new items one at a time and watch your baby for any signs of a reaction. It's a good idea to check with your pediatrician first, especially if food allergies run in your family or if your child has allergy risk factors like eczema.
Never give babies whole nuts, as they can be a choking hazard. Try soft forms like cashew or almond butter.
Takeaways
When you have a tree nut allergy, your immune system overreacts to proteins found in nuts that grow on trees. The best way to manage this allergy is to avoid eating tree nuts or anything that contains them. You'll need to carry epinephrine auto-injectors in case of a serious reaction (anaphylaxis). You might ask your doctor about treatment options like oral immunotherapy or omalizumab, which reduce the chances of anaphylaxis after an accidental exposure to tree nuts.
Tree Nut Allergy FAQs
Can you eat chocolate with a tree nut allergy?
Read the label on chocolate products before you eat them. Chocolate itself doesn't contain tree nuts, but many chocolate candies contain tree nuts. So do things like chocolate-hazelnut spreads.
How rare is a tree nut allergy?
Tree nut allergies are among the nine most common food allergies in both kids and adults. They affect 0.5% to 1% of the population in the U.S.
How long does it take for a tree nut allergy to show?
Symptoms of a tree nut allergy usually show up within minutes after you're exposed to tree nut proteins. But in some cases, it may a few hours
What are the first signs of a nut allergy?
Symptoms vary from person to person and from reaction to reaction. But the first signs are likely to be mild ones such as:
- A rash or hives
- Tingling or tightening in your mouth and throat
- A runny nose
- Swollen lips
- Digestive symptoms like stomach cramps, nausea, or vomiting
These symptoms can be followed by a serious reaction.
Can you suddenly develop a tree nut allergy?
Most people with tree nut allergies first had them before the age of 5. But it's possible for adults to develop nut allergies, even if they've eaten tree nuts before with no problem.
Can the smell of tree nuts cause an allergic reaction?
The odor of tree nuts alone can't cause an allergic reaction because it doesn't contain nut proteins. But you might have a reaction if you breathe in bits of nuts that get into the air while they're being ground or crushed.
