What is nut allergy?

Nut allergy means peanut or tree nuts like almond, Brazil or macadamia nut, cashew, hazelnut, pecan, pistachio or walnut

Let’s get it out there… Nut allergy can be challenging. Nuts are a versatile ingredient as well as a snack so the allergens are everywhere. Food companies use them to add crunch and creaminess, as a thickener, and to replace grains and meat. But it’s not only what you might eat. Nut oils are in cosmetics and toiletries. Bird seed and pet food can be full of peanut too.

If that sounds overwhelming, it isn't meant to. Nut allergies do take careful management. They can start at a young age and cause severe reactions. But getting a diagnosis unlocks a ton of medical advice and support. The more you know, the better equipped you are to deal with your nut allergy symptoms. So read on.

Nut allergy: Tree nuts vs peanuts

Nut allergy is a broad name for reactions to two different foods: tree nuts and peanuts. Peanut allergy affects around 1.8% of adult Americans, tree nut allergy up to 1%.

Tree nuts grow on trees and have hard shells. That’s the botanical definition. Some nuts that cause allergies are actually seeds. But if it looks like a nut, tastes nutty and there’s a tree involved, then it could cause tree nut allergy.

Peanuts do not grow on trees. They're a legume like beans and peas except the pods are underground (why they’re also called groundnuts). You may be allergic to tree nuts and to peanuts, or you may not. Almost a third of people with peanut allergy react to both. Your healthcare provider may advise you to avoid all nuts in case of cross-contact in the factory.

By the way, pine nuts are not tree nuts though they may be listed as such. Nor are coconuts. Or even the spice nutmeg despite its shell and growing on a tree, and its sweetly nutty taste.

More about nut allergy

Peanuts are a cousin of the bean and grow in pods underground. They can cause severe allergy symptoms

Common nut allergy triggers

A peanut is a peanut but a tree nut could be many different things. These are among the most common tree nuts linked to allergic reactions:

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

Shea nuts also appear on some tree nut lists. You can find shea butter in make-up and skincare products, and in some confectionery instead of cocoa butter. But it’s usually highly refined. And that seems to remove the proteins, which are what trigger allergy.

Nut allergy: Back to the beginning

Allergies happen when your immune system reacts to a harmless substance or allergen as though it's a threat. In this case, it thinks you need protecting from nut proteins.

There are two stages to developing a nut allergy. The first contact with nuts puts your immune system on alert. It goes "uh-oh" and makes Immunoglobulin E (IgE) antibodies. The antibodies keep watch in case you ever meet another nut. You're sensitized.

For some people it stops there. Others go on to become allergic to nuts. Eat one again and the antibodies message other cells around the body to release chemicals like histamine. And you get food allergy symptoms.

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Babies can develop an allergy to peanuts as early as six months old. Tree nut allergy more often shows itself after the age of one. And kids often don’t grow out of these allergies.

When does nut allergy start?

Nut allergy commonly starts in childhood and kids often don’t grow out of it, unlike other early food allergies. Babies can even develop an allergy to peanuts as early as six months old. Tree nut allergy more often shows itself after the age of one, perhaps because kids may not have eaten them until then. By six years old the numbers for tree nuts and peanuts are similar. It is possible to become allergic to nuts as a grown-up but it’s less common.

Can you stop nut allergy before it starts?

Allergy seems to run in families. A child is more likely to react to tree nuts or peanuts if a parent or sibling does too. Egg allergy or having an allergic condition like severe eczema also increases the risk.

Researchers have been looking at whether introducing nuts earlier could help at-risk children. The guidelines now are to start giving babies peanut from six months old or before to encourage the immune system to accept the allergens in later life. Always talk to your healthcare provider first.

Nut allergy symptoms

Even a microscopic amount of peanuts and tree nuts can trigger a reaction. You’d usually expect to feel something within two hours. But it could be seconds. These are typical nut allergy symptoms. You might get some or all of them:

  • A raised, itchy red rash (hives) – sometimes the skin can turn red and itchy but not raised
  • Tingling or itching in the mouth
  • Swelling of the face, mouth, throat or other parts of the body
  • Difficulty swallowing
  • Wheezing or shortness of breath
  • Feeling dizzy and lightheaded
  • Feeling sick (nausea) or vomiting
  • Abdominal pain or diarrhea
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How to spot a severe reaction from nut allergy

Like many food allergies, peanuts and tree nuts can cause anaphylaxis. This is a life-threatening reaction. Call an ambulance straight away if you or someone you’re with gets any of these severe symptoms:

  • Feeling lightheaded or faint
  • Difficulties with breathing, such as fast or shallow breaths
  • Wheezing
  • A fast heartbeat
  • Clammy skin
  • Confusion and anxiety
  • Collapsing or losing consciousness
  • Tingling in the hands, feet, lips or scalp

An allergic reaction may be more likely to be severe if you’re feeling stressed or unwell, are on some types of medication or take exercise just before or after eating.

Nut oils: Allergic reactions not from food

We’ve talked about shea butter already. Almond and peanut oils are also common ingredients in bath, body and beauty products. Some use macadamia nut. These oils often highly refined. Processing alters the allergenic proteins, which reduces the risk. But cold-pressed oils in more “natural” products could give you a rash or other nut allergy symptoms.

Laws about food labels don’t cover cosmetics and toiletries. Manufacturers list what’s in their products. But the international naming convention for plant-based ingredients favors Latin. This is what to look out for.

Also known as…

Nuts and cross-reactive allergens may have Latin names on the labels of non-food products.
Peanut Sweet almond
Arachis, Arachis hypogaea
Prunus dulcis, Prunus amygdalus dulcis
Bitter almond Shea butter
Prunus amara, Prunus amydalus amara
Vitellaria paradoxa
Sesame Soya
Sesamum indicum
Glycine soja, Glycine max

Some topical medicines like eardrops and skin creams can contain peanut oil. There may be a warning on the packaging but read the information leaflet carefully too. Soya and sesame can cause cross-reactions if you have peanut allergy. So look out for those too and speak to your healthcare provider.

Nut allergy or cross-reaction?

Cashew allergy can give you symptoms from pistachio. The same goes for walnut and pecan.

It’s not just different tree nuts that share similar allergenic proteins. Other foods can confuse your overactive immune system. People with tree nut allergy may get symptoms when they eat sesame. There’s also a cross-reaction between cashews and pink peppercorns, and between peanuts and other legumes like soy and lupin.

Cross-reactions can work the other way too. You may get symptoms from almonds, hazelnuts or peanuts if you have birch pollen allergy. It's called pollen food syndrome or oral allergy syndrome. Symptoms are usually localized and mild but can be severe too. Kids may notice it first when hay fever starts giving them a runny nose.

Hay fever in children

This happy little boy reading on his mom’s lap under a tree is old enough to have hay fever but it seems to be under control

Testing for nut allergy

It may take more than one allergy test for your healthcare provider to be able to give an accurate diagnosis. Nut allergy is complex. About half of all kids who are allergic to one tree nut will react to another.

The first step is often a skin prick test. Then an allergy blood test, either looking for whole allergens or for specific proteins. The latter can help distinguish pollen food syndrome from nut allergy and assess your risk of severe reactions such as anaphylaxis.

An oral food challenge can be useful if other test results are inconclusive or to check if a child has outgrown their nut allergy. It happens at the doctor's office and involves eating tiny amounts of peanut butter, say, then building up little by little. Specially trained medical staff monitor you for allergic symptoms, ready with treatment if you need it.

Immunotherapy for peanut allergy

There's no cure for nut allergies but desensitizing your immune system could help prevent a severe reaction. Immunotherapy is available for peanut allergy but not tree nuts yet. This long-term treatment involves repeated tiny doses of peanut allergen over several years. It isn't suitable for everyone. Your healthcare provider can tell you more.

Symptom relievers and emergency treatment

Medications like antihistamine are available to ease milder nut allergy symptoms. Your healthcare provider may also prescribe an epinephrine (adrenaline) auto-injector in case of a severe allergic reaction. The advice is to carry two of them with you at all times. Show your friends and family how to use the auto-injector too. An allergy bracelet or necklace will help people know how to help you if you're exposed to nuts by accident.

You should always go to the emergency room if you have a severe reaction because there can be a second wave of symptoms up to eight hours later.

Keeping leftovers in tubs on specific shelves in the refrigerator helps stop cross-contamination triggering food allergies

Food allergy: A very
practical guide

Be alert for nut allergy triggers

It’s essential to avoid peanuts or your problem tree nut. You’ll find information about food allergen labelling and lots of useful tips in our food allergy article. Here are some known risks to be aware of beyond the obvious breakfast cereals and snack bars:

  • The bakery and coffee shop: Cookies, pastries and cakes often contain nuts. Gluten-free baked goods tend to replace grains with almond meal. And almond milk is a popular alternative to dairy in flat whites and frappuccinos.
  • Vegan and vegetarian recipes: Nuts are a rich source of protein. You’ll find them in non-meat mince, burgers and roasts. Particularly walnuts.
  • Ice-cream parlors: Scoops dipped into ice-cream containing tree nuts or peanuts could cause cross-contamination. So could nutty sprinkles.
  • Your local Italian deli: Mortadella is made with pistachios; did you know that?
  • Cocktails: Nutty syrups and alcoholic drinks are best avoided. Nuts can sneak in under the radar too, flavoring gin for example.
  • Takeaway or eat in: Nuts are common in Thai food, as well as Chinese, Vietnamese, Indian, and Mexican. It may be obvious. Or the chef may be using unrefined nut oil or thickening sauces with nuts. Cross-contamination can be a problem in restaurant kitchens too.
  • Dinner with friends: Picking nuts out of the salad for you doesn’t make it safe to eat. Traces of allergens can linger on crockery, cutlery and cooking equipment too.

If in doubt – ever – ask if nuts could be in what you’re eating or drinking. Or any other product for that matter. You can always call the manufacturer.

And here’s one last tip. Choose nut-free pet food, especially if you’ve got an allergic toddler who’s in love with the dog. Allergens can linger in the animal's saliva and children aged one to two years old may put licked hands to their mouths up to 80 times an hour.

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