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Nut and Peanut Allergy

Reviewed by: Magee Defelice, MD

Oh, nuts! They sure can cause you trouble if you're allergic to them — and a growing number of kids are these days.

So what kind of nuts are we talking about? Peanuts, for one, though they aren't truly a nut. They're a legume (say: LEH-gyoom), like peas and lentils. A person also could be allergic to nuts that grow on trees, such as almonds, walnuts, pecans, cashews, hazelnuts, Brazil nuts, and pistachios.

When you think of allergies, you might picture lots of sneezing and runny noses. But unlike an allergy to spring flowers, a nut or peanut allergy can cause difficulty breathing and other very serious health problems. That's why it's very important for someone with a nut or peanut allergy to avoid eating nuts and peanuts, which can be tough because they're in lots of foods.

What Happens With a Tree Nut or Peanut Allergy?

Your immune system normally fights infections. But when someone has a nut allergy, it overreacts to proteins in the nut. If the person eats something that contains the nut, the body thinks these proteins are harmful invaders and responds by working very hard to fight off the invader. This causes an allergic reaction.

What Are the Signs & Symptoms of a Nut Allergy?

When someone with a peanut or tree nut allergy has something with nuts in it, the body releases chemicals like histamine (pronounced: HISS-tuh-meen).

This can cause symptoms such as:

  • wheezing
  • trouble breathing
  • coughing
  • sneezing
  • hoarseness
  • throat tightness
  • stomachache
  • vomiting
  • diarrhea
  • itchy, watery, or swollen eyes
  • hives
  • swelling
  • a drop in blood pressure
  • dizziness or fainting
  • anxiety or a feeling something bad is happening

Reactions to foods, like peanuts and tree nuts, can be different. It all depends on the person — and sometimes the same person can react differently at different times.

In the most serious cases, a nut or peanut allergy can cause anaphylaxis (say: an-uh-fuh-LAK-sis). Anaphylaxis is a sudden, life-threatening allergic reaction. A person's blood pressure can drop, breathing tubes can narrow, and the tongue can swell.

People at risk for this kind of a reaction have to be very careful and need a plan for handling emergencies, when they might need to use special medicine to stop these symptoms from getting worse.

What Will the Doctor Do?

If your doctor thinks you might have a nut or peanut allergy, he or she will probably send you to see a doctor who specializes in allergies. The (allergy specialist) will ask you about past reactions and how long it takes between eating the nut or peanut and getting the symptoms, such as hives.

The allergist may also ask whether anyone else in your family has allergies or other allergy conditions, such as eczema or asthma. Researchers aren't sure why some people have food allergies and others don't, but they sometimes run in families.

The allergist may also want to do a skin test. This is a way of seeing how your body reacts to a very small amount of the nut that is giving you trouble. The allergist will use a liquid extract of the nut that seems to be causing you symptoms.

During skin testing, a little scratch on your skin is made (it will be a quick pinch, but there are no needles!). That's how just a little of the liquid nut gets into your skin. If you get a reddish, itchy, raised spot, it shows that you may be allergic to that food or substance.

Skin tests are the best test for food allergies, but if more information is needed, the doctor may also order a blood test. At the lab, the blood will be mixed with some of the food or substance you may be allergic to and checked for antibodies.

It's important to remember that even though the doctor tests for food allergies by carefully exposing you to a very small amount of the food, you should not try this at home! The only place for an allergy test is at the allergist's office, where they are specially trained and could give you medicine right away if you had a reaction.

How Is a Tree Nut or Peanut Allergy Treated?

There is no special medicine for nut or peanut allergies and many people don't outgrow them. The best treatment is to avoid the nut. That means not eating that nut, and also avoiding the nut when it's mixed in foods. (Sometimes these foods don't even taste nutty! Would you believe chili sometimes contains nuts to help make it thicker?)

Staying safe means reading food labels and paying attention to what they say about how the food was produced. Some foods don't contain nuts, but are made in factories that make other items that do contain nuts. The problem is the equipment can be used for both foods, causing "cross-contamination." That's the same thing that happens in your own house if someone spreads peanut butter on a sandwich and dips that same knife into the jar of jelly.

After checking the ingredients list, look on the label for phrases like these:

  • "may contain tree nuts"
  • "produced on shared equipment with tree nuts or peanuts"

People who are allergic to nuts also should avoid foods with these statements on the label. Some of the highest-risk foods for people with peanut or tree nut allergy include:

  • cookies and baked goods
  • candy
  • ice cream
  • Asian and African foods
  • sauces (nuts may be used to thicken dishes)

Talk to your allergist about how to stay safe in the school cafeteria. Also ask about how you should handle other peanut encounters, like at restaurants or stadiums where people are opening peanut shells. People with nut allergies usually won't have a reaction if they breathe in small particles. That's because the food usually has to be eaten to cause a reaction.

Have an Emergency Plan

If you have a nut or peanut allergy, you and a parent should create a plan for how to handle a reaction, just in case. That way your teachers, the school nurse, your basketball coach, your friends — everyone will know what a reaction looks like and how to respond.

To immediately treat anaphylaxis, doctors recommend that people with a nut or peanut allergy keep a shot of epinephrine (say: eh-puh-NEH-frin) with them. This kind of epinephrine injection comes in an easy-to-carry container. You and your parent can work out whether you carry this or someone at school keeps it on hand for you. You'll also need to identify a person who will give you the shot.

You might want to have antihistamine medicine on hand too for mild reactions. If anaphylaxis is happening, this medicine is never a substitute for epinephrine. After getting an epinephrine shot, you need to go to the hospital or other medical facility, where they will keep an eye on you for at least 4 hours and make sure the reaction is under control and does not come back.

What Else Should I Know?

If you find out you have a nut or peanut allergy, don't be shy about it. It's important to tell your friends, family, coaches, and teachers at school. The more people who know, the better off you are because they can help you stay away from the nut that causes you problems.

Telling the server in a restaurant is also really important because he or she can steer you away from dishes that contain nuts. Likewise, a coach or teacher would be able to choose snacks for the group that don't contain nuts.

It's great to have people like your parents, who can help you avoid nuts, but you'll also want to start learning how to avoid them on your own.

Reviewed by: Magee Defelice, MD
Date reviewed: August 2018