Patient education: Peanut, tree nut, and seed allergy (The Basics)

What is a peanut, tree nut, or seed allergy? — 

A food allergy is when the immune system acts like a certain food is harmful to the body. The immune system is the body's infection-fighting system.

Allergies to the following foods are common:

●Peanuts

●Tree nuts, such as walnuts, cashews, and hazelnuts

●Seeds, such as sesame, mustard, sunflower, and flax

Most often, allergic reactions happen from eating the food or something that contains the food. Touching the food can also cause a skin reaction.

What are the symptoms of an allergic reaction? — 

With "classic" food allergies, also called "IgE-mediated" food allergies, common symptoms include:

●Hives, which are raised or puffy areas of skin that are itchy (picture 1 and picture 2)

●Flushing

●Swelling, especially of the face, eyelids, or lips (picture 3 and picture 4)

●Trouble breathing, noisy breathing (wheezing), or coughing

●Nausea, vomiting, or diarrhea

●Feeling dizzy or passing out

●Looking sick, seeming sleepier than usual, or not acting normally (in babies and young children)

The above symptoms often start quickly, usually minutes to 1 hour after having the food.

When an allergic reaction is more severe, it is called "anaphylaxis." This can make you very sick, very quickly. If not treated, it can lead to death. But this is rare.

Symptoms can differ from person to person. Also, a person can have different symptoms each time they have an allergic reaction.

Is there a test for a peanut, tree nut, or seed allergy? — 

Yes. Your doctor or nurse will ask about your symptoms. You might need to see an allergy specialist, called an "allergist."

Your doctor can order tests such as:

●Blood tests – These look for proteins the body makes when it is having an allergic response to the nut or seed. These proteins are called "IgE antibodies." For example, your doctor can test IgE to whole peanut or tree nuts. For peanuts and some tree nuts, more specific blood tests called "component testing" can be done. These look for IgE to certain proteins found in peanuts. The results can tell your doctor more information about your allergy and how best to manage it.

●Skin test – This involves pricking your skin with a device that contains a tiny amount of the nut or seed. If you get a red, itchy bump, like a mosquito bite, it means you are allergic to that nut or seed.

If the doctor still cannot tell if you or your child has a nut or seed allergy, they might order a test called an "oral food challenge." This involves eating a small serving of the food and gradually eating more to see if it causes symptoms. For safety reasons, this is only done in a doctor's office or hospital.

Can a peanut, tree nut, or seed allergy be cured? — 

As of now, there is no cure for a nut or seed allergy. But there are treatments that might help. These include:

●Oral immunotherapy ("OIT") – This involves getting small amounts of the food in a controlled way. You start treatment in a clinic or hospital, where you can be monitored and treated if you have a reaction. Then, you continue to take daily doses at home. The goal is to increase the "dose" of the food very slowly over time, so your immune system does not react to it. Each dose increase is done in the clinic or hospital.

●Omalizumab (brand name: Xolair) – This medicine comes as a shot. You start treatment in a clinic or hospital, where you can be monitored and treated if you have a reaction. Then, you get a shot every 4 weeks. After your first shot, you might be able to give yourself the rest of the shots at home.

Getting treatment regularly might make you less likely to have a reaction if you are accidentally exposed to the nut or seed.

Both OIT and omalizumab come with risks. They are not likely to make an allergy go away completely, and most people need to continue to avoid the nut or seed. But they might be an option in certain situations. If you want to learn more about them, talk with your doctor or nurse.

How are allergic reactions treated? — 

Severe allergic reactions are treated with medicine called epinephrine. Ambulance crews and doctors can give it. People who had anaphylaxis before often get a prescription for epinephrine. It comes in 2 forms:

●A device called an "autoinjector" (sample brand names: Auvi-Q, EpiPen), which is a shot you can give yourself (figure 1)

●A spray that goes in the nose (brand name: neffy) (figure 2)

If your doctor prescribes epinephrine:

●They will show you how to use it.

●They will give you instructions for when to use it.

●Keep it with you at all times. Most doctors recommend carrying 2 doses in case you need a second dose. You might need a second dose if:

•Your symptoms do not go away completely.

•Your symptoms go away, but then start to come back.

•You used an autoinjector that did not work correctly the first time.

Call for an ambulance (in the US and Canada, call 9-1-1):

●After you use epinephrine – The medicine does not last very long in the body. Symptoms can sometimes come back as the medicine wears off. In the hospital, doctors can watch you and give you more medicine if needed.

●If you think someone is having anaphylaxis, and you do not have epinephrine

Your doctor might also recommend an antihistamine, such as cetirizine (sample brand name: Zyrtec). You can get these without a prescription. They can help relieve mild food allergy symptoms like itching and hives. They do not treat anaphylaxis.

How can I prevent an allergic reaction? — 

The best way is to completely avoid the nut or seed. Even a tiny bite that contains the food can cause a big reaction.

●To know whether a food contains the nut or seed, read its ingredient label. Some countries (including the US) have laws that make companies clearly list whether a food has certain common "allergens" in it. These include peanuts, tree nuts, and sesame.

●Some foods have warning labels for food allergies, such as "May contain peanuts or tree nuts." These might have been made on machines or in factories that are also used for other foods that contain nuts. Talk to your doctor about whether you should avoid these foods.

●If you eat at a restaurant, bakery, or ice cream shop, tell your server about your allergy. Foods that are especially likely to contain peanuts, tree nuts, or seeds include baked goods and Asian, African, and Mexican foods.

●Non-food items can also have nuts and seeds in them. These include medicines, vaccines, cosmetics, and craft supplies. Most countries (including the US) do not have laws that make companies list if these items have potential allergens in them. If you think you are allergic to any non-food items, talk to your doctor about ways to avoid them.

What else should I know if I have a peanut, tree nut, or seed allergy? — 

People with a nut or seed allergy:

●Can have an allergic reaction if they share saliva with (kiss) someone who ate the nut or seed and did not brush their teeth after

●Can get hives on their skin if they touch the nut or seed

●Could have an allergic reaction by breathing in tiny pieces of the nut or seed in the air – This can happen if they are around many people eating peanuts at the same time, such as at a baseball game or on an airplane.

●Can wear a medical alert bracelet or necklace to tell others about their nut or seed allergy – If you cannot wear a bracelet or necklace, you can carry a document called an "allergy passport" or "allergy card."

Some people have allergies to more than 1 food. If you have other food allergies, you need to avoid those foods, too.

Your doctor or nurse might have you work with a dietitian (food/nutrition expert). They can help you learn how to:

●Avoid the food you are allergic to

●Use other foods in place of the food you are allergic to

●Make sure you get the nutrients you need

What if my child has a peanut, tree nut, or seed allergy? — 

Tell their caregivers, schools, and camps. You should:

●Tell them which foods your child can and cannot eat.

●Make a plan so they know how to treat an allergic reaction.

●Make sure they know where your child's epinephrine is, and how and when to use it.

●Make sure they know how to reach you or your child's doctor in case of an emergency.

Will my child outgrow their peanut, tree nut, or seed allergy? — 

Most children do not outgrow their nut or seed allergy. Your child's doctor will monitor their allergy over time to see whether they outgrow it.

Where can I learn more? — 

You can get more information about food allergies from Food Allergy Research & Education ("FARE") at www.foodallergy.org.

More on this topic

Patient education: Food allergy (The Basics)
Patient education: Hives (The Basics)
Patient education: Angioedema (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: How to give epinephrine (The Basics)
Patient education: Allergy skin testing (The Basics)

Patient education: Food allergy symptoms and diagnosis (Beyond the Basics)
Patient education: Food allergen avoidance (Beyond the Basics)
Patient education: Hives (urticaria) (Beyond the Basics)
Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)
Patient education: Anaphylaxis treatment and prevention of recurrences (Beyond the Basics)
Patient education: Using an epinephrine autoinjector (Beyond the Basics)