Browse A-Z
More <
bookmarks-menu

Nut allergies

Show Alternative Names
Food allergy - nuts
Peanut allergy
Nut allergy

A nut allergy is a type of immune response triggered by tree nuts and peanuts. Peanuts are legumes, not nuts, but many people who are allergic to peanuts are also allergic to nuts. Nut allergies are a type of food allergy.

Most people who develop nut allergies will have them for the rest of their life.

Causes

The immune system normally protects the body against harmful substances, such as bacteria and viruses. It also reacts to foreign substances called allergens. These are usually harmless, and in most people, do not cause a problem.

If you have a nut allergy, your immune system is overly reactive. When the body identifies a nut allergen, it launches a response. Chemicals such as histamines are released. These chemicals cause allergy symptoms. These symptoms occur every time you come in contact with even a small amount of the nut allergen.

Risk factors for nut and other food allergies include:

  • Having eczema as a child
  • How early you were exposed to nuts in childhood

Other theories suggest that changes to the microbiome may be a factor. The microbiome is all of the tiny organisms (bacteria, fungi, and others) that normally live on and in our bodies. A number of things may affect the microbiome, including cesarean birth, antibiotic use, and more people living in urban settings. Research is being done to better understand how these things affect the microbiome.

Symptoms

Symptoms usually begin quickly after eating nuts.

Nut allergy symptoms include:

  • Hives (urticaria)
  • Skin rashes
  • Itching of the mouth, throat, eyes, skin, or any other area
  • Stomach cramps, diarrhea, nausea, or vomiting
  • Stuffy nose, runny nose
  • Swelling (angioedema), especially of the eyelids, face, lips, and tongue
  • Trouble swallowing or breathing due to swelling in the throat

Nut allergies can cause a life-threatening, whole-body reaction called anaphylaxis. In addition to the above symptoms, you may have low blood pressure and blocked airways. These severe allergy symptoms are a medical emergency.

Exams and Tests

If you suspect that you or your child has a nut allergy, see an allergy specialist doctor (allergist).

Blood or skin tests may be used to confirm that you have an allergy. These tests are:

  • Allergy skin test where a small amount of the nut allergen is introduced into the body by pricking the skin.
  • Immunoglobulin E (IgE) blood test, which measures levels of IgE in the blood

Allergy testing - Animation

Every time you walk into your backyard, you start sneezing, sniffling, and feeling like you want to go back indoors. You're pretty sure you have an allergy, but what are you allergic to? Pollen? Grass? Your neighbor's Golden retriever? The only way to know for sure what's making you sneeze is to have allergy tests at your doctor's office. Let's talk about allergy testing. Your doctor may do one or more of several different types of allergy tests to see what's causing your allergies. One is a skin test. It can diagnose allergies to things like mold, pollen, animal fur, insect stings, and foods. With a skin test, your doctor will place a small amount of one substance, or several different substances just under the surface of the skin on your arm or back. You'll feel a little prick when the substances are placed under your skin. After 15 minutes or so, the doctor will look for signs that you're having a reaction. Usually your skin will get red or swollen if you're allergic to something in the test. Another way to test for allergies is to put a patch of the substance on your skin and leave it there for about 2 days, checking the area every day for any sign of a reaction. You may have a blood test. A blood test measures the amount of substances called antibodies that your body produces in response to a certain allergen. If you're allergic to food, you can try avoiding whatever foods you think might be making you sick. This is called elimination testing. Then you add back in each of the foods, one at a time, and look for signs of an allergic reaction. Your doctor may also try to trigger an allergic reaction in the office by having you eat the food or breathe in the substance you think causes your allergy. This is called a challenge test. The one risk to this test is that, if you're severely allergic, you could have a very serious reaction. Your doctor will watch you very closely during this test to make sure you're safe. Allergy tests are usually pretty accurate. But sometimes what bothers you in the real world won't show up on the test. If you have one test and it doesn't find your allergy trigger, your doctor may recommend having another type of test. Don't worry if it takes a while to find the source of your allergies. Your doctor will keep trying different methods until you learn exactly what's making you so miserable.

If results from these tests are unclear, you may have other tests.

A double-blind food challenge is one way to diagnose a nut allergy. During this test, you and your health care provider will not know what you are eating.

With elimination diets, you avoid the suspected food until your symptoms disappear. Then you start eating the foods again to see if you develop an allergic reaction.

In provocation (challenge) testing, you eat a small amount of the suspected food under medical supervision. This type of test may cause severe allergic reactions. Challenge testing should only be done by a trained provider.

Never try to cause a reaction or reintroduce a food on your own. These tests should only be done under the guidance of a provider, especially if your first reaction was severe.

Children 5 years of age and younger with atopic dermatitis should be tested for nut allergies if:

  • Dermatitis persists despite treatment
  • Allergic symptoms appear right after eating a specific nut

Treatment

Treatment mainly involves:

  • Avoiding the nut allergen.
  • Knowing what to do in case of accidental exposure.
  • Some people may benefit from treatment that helps desensitize them to the allergen.

AVOIDING NUTS

The easiest way to prevent an allergic reaction is to avoid all nuts and peanuts and foods that contain them. Often, nuts and peanuts are processed in the same facility. This increases the risk for cross-contact exposure. Cross-contact is when an allergen is accidentally transferred from one food to another. For example, if you use a knife to spread peanut butter, wipe it off without washing it, and then use it for jelly, the jelly will become contaminated with the proteins from the peanut butter. Even very small amounts of an allergen can cause a reaction.

To avoid consuming nuts you should:

  • Read food labels carefully to avoid any foods that contain nuts. These include sweets and baked goods, cereal and granola, whole-grain breads, sauces, soups, and many others.
  • Avoid foods with labels that say "may contain traces of" a nut allergen or "produced in a facility" that manufactures nuts or peanuts.
  • Always let your restaurant server know that you have a nut allergy. Ask them to make sure there are no nuts or peanuts in your food.

EMERGENCY TREATMENT

There may be a time that you accidentally eat foods with nuts. So you need to know what to do if you are exposed.

Severe allergic reactions (anaphylaxis) need to be treated with a medicine called epinephrine. It can be life-saving when given right away.

Your provider can show you how to use an epinephrine auto-injector such as EpiPen and Auvi-Q. You should have it with you at all times.

If you develop any type of serious or whole-body reaction (even hives) after eating the nut allergen:

  • Inject the epinephrine.
  • Then call 911 or the local emergency number and follow the instructions you are given, or, go straight to the hospital.

IMMUNOTHERAPY

Oral immunotherapy (desensitization) is a treatment to help you be less sensitive to the nut allergen. This therapy must be done under an allergist's guidance. The allergist will give increasing amounts of the nut allergen (most often peanut powder). This raises the threshold that triggers allergic symptoms. Immunotherapy is not a cure, but it can help reduce the risk of a severe reaction. At the present time, the FDA has only approved oral immunotherapy for peanut allergy.

Support Groups

More information and support for people with nut allergies and their families can be found at:

Outlook (prognosis)

Nut allergies usually last a lifetime. Only about 10% of people will outgrow a tree nut allergy. About 20% of people with peanut allergy will outgrow it.

Possible Complications

Anaphylaxis is a severe, whole-body allergic reaction that is a life-threatening complication.

When to Contact a Medical Professional

Anyone who has had an allergic reaction to any nut should be seen by an allergist.

Steps to take when a nut allergy reaction occurs:

  • Call 911 or the local emergency number if you have any serious or whole-body reactions, particularly wheezing or difficulty breathing, after eating any nut.
  • If your provider prescribed epinephrine for severe reactions, inject it as soon as possible, even before calling 911. The sooner you inject the epinephrine, the better.

Prevention

Breastfeeding may help prevent allergies from developing in your baby. Otherwise, there is no known way to prevent food allergies.

Avoiding peanuts in early childhood does not appear to prevent, and may even enhance, the development of a peanut allergy. Providers now suggest introducing peanut-containing foods to infants, which may help prevent a peanut allergy. Talk to your child's provider to learn more.

Babies with severe atopic dermatitis can be given peanuts between 4 to 6 months of age to decrease the risk of nut allergies.

Review Date: 12/24/2023

Reviewed By

Stuart I. Henochowicz, MD, FACP, Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

References

Albright D, Larkin A, Chong HJ. Allergy and immunology. In: Zitelli BJ, McIntire SC, Nowalk AJ, Garrison J, eds. Zitelli and Davis' Atlas of Pediatric Physical Diagnosis. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 4.

Nowak-Wegrzyn A, Burks AW, Sampson HA. Reaction to foods. In: Burks AW, Holgate ST, O’Hehir RE, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 79.

Paller AS, Mancini AJ. Urticarias and other hypersensitivity disorders. In: Paller AS, Mancini AJ, eds. Paller and Mancini -- Hurwitz Clinical Pediatric Dermatology. 6th ed. Philadelphia, PA: Elsevier; 2022:chap 20.

Sicherer SH, Lack G, Jones SM. Food allergy management. In: Burks AW, Holgate ST, O'Hehir RE, eds. Middleton's Allergy: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 82.

Disclaimer

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

All
Videos
Images
Allergy testing

Allergy testing

Animation

Antibodies - Illustration Thumbnail

Antibodies

Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

Illustration

Anaphylaxis - Illustration Thumbnail

Anaphylaxis

Anaphylaxis is an acute systemic (whole body) type of allergic reaction which occurs when a person has become sensitized to a certain substance or allergen and is again exposed to the allergen. Some drugs, such as those used for pain relief or for x-rays, may cause an anaphylactoid reaction on first exposure. Histamines and other substances released into the bloodstream cause blood vessels to dilate and tissues to swell. Anaphylaxis may be life threatening if obstruction of the airway occurs, if blood pressure drops, or if heart arrhythmias occur.

Illustration

Food allergies - Illustration Thumbnail

Food allergies

The body's immune system normally reacts to the presence of toxins, bacteria or viruses by producing a chemical reaction to fight these invaders. However, sometimes the immune system reacts to ordinarily benign substances such as food or pollen, to which it has become sensitive. This overreaction can cause symptoms from the mild (hives) to the severe (anaphylactic shock) upon subsequent exposure to the substance. An actual food allergy, as opposed to simple intolerance due to the lack of digesting enzymes, is indicated by the production of antibodies to the food allergen, and by the release of histamines and other chemicals into the blood.

Illustration

Read food labels - Illustration Thumbnail

Read food labels

Allergic reactions to a certain food can include diffuse hives, hoarse voice, wheezing, and, in severe reactions, low blood pressure and closing down of the windpipe. Medications such as antihistamines and skin creams may provide some relief from itching and rashes, but the best way to prevent future allergic reactions is to avoid the offending food in the first place. Reading the labels contained on most products is a useful way to find a certain food that a person may want to avoid.

Illustration

 
Allergy testing

Allergy testing

Animation

 
Antibodies - Illustration Thumbnail

Antibodies

Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

Illustration

Anaphylaxis - Illustration Thumbnail

Anaphylaxis

Anaphylaxis is an acute systemic (whole body) type of allergic reaction which occurs when a person has become sensitized to a certain substance or allergen and is again exposed to the allergen. Some drugs, such as those used for pain relief or for x-rays, may cause an anaphylactoid reaction on first exposure. Histamines and other substances released into the bloodstream cause blood vessels to dilate and tissues to swell. Anaphylaxis may be life threatening if obstruction of the airway occurs, if blood pressure drops, or if heart arrhythmias occur.

Illustration

Food allergies - Illustration Thumbnail

Food allergies

The body's immune system normally reacts to the presence of toxins, bacteria or viruses by producing a chemical reaction to fight these invaders. However, sometimes the immune system reacts to ordinarily benign substances such as food or pollen, to which it has become sensitive. This overreaction can cause symptoms from the mild (hives) to the severe (anaphylactic shock) upon subsequent exposure to the substance. An actual food allergy, as opposed to simple intolerance due to the lack of digesting enzymes, is indicated by the production of antibodies to the food allergen, and by the release of histamines and other chemicals into the blood.

Illustration

Read food labels - Illustration Thumbnail

Read food labels

Allergic reactions to a certain food can include diffuse hives, hoarse voice, wheezing, and, in severe reactions, low blood pressure and closing down of the windpipe. Medications such as antihistamines and skin creams may provide some relief from itching and rashes, but the best way to prevent future allergic reactions is to avoid the offending food in the first place. Reading the labels contained on most products is a useful way to find a certain food that a person may want to avoid.

Illustration

 
##RemoveMe##
 

Allergy testing - Animation

Every time you walk into your backyard, you start sneezing, sniffling, and feeling like you want to go back indoors. You're pretty sure you have an allergy, but what are you allergic to? Pollen? Grass? Your neighbor's Golden retriever? The only way to know for sure what's making you sneeze is to have allergy tests at your doctor's office. Let's talk about allergy testing.

Your doctor may do one or more of several different types of allergy tests to see what's causing your allergies. One is a skin test. It can diagnose allergies to things like mold, pollen, animal fur, insect stings, and foods.

With a skin test, your doctor will place a small amount of one substance, or several different substances just under the surface of the skin on your arm or back. You'll feel a little prick when the substances are placed under your skin. After 15 minutes or so, the doctor will look for signs that you're having a reaction. Usually your skin will get red or swollen if you're allergic to something in the test.

Another way to test for allergies is to put a patch of the substance on your skin and leave it there for about 2 days, checking the area every day for any sign of a reaction.

You may have a blood test. A blood test measures the amount of substances called antibodies that your body produces in response to a certain allergen.

If you're allergic to food, you can try avoiding whatever foods you think might be making you sick. This is called elimination testing. Then you add back in each of the foods, one at a time, and look for signs of an allergic reaction.

Your doctor may also try to trigger an allergic reaction in the office by having you eat the food or breathe in the substance you think causes your allergy. This is called a challenge test. The one risk to this test is that, if you're severely allergic, you could have a very serious reaction. Your doctor will watch you very closely during this test to make sure you're safe.

Allergy tests are usually pretty accurate. But sometimes what bothers you in the real world won't show up on the test. If you have one test and it doesn't find your allergy trigger, your doctor may recommend having another type of test. Don't worry if it takes a while to find the source of your allergies. Your doctor will keep trying different methods until you learn exactly what's making you so miserable.

 

Allergy testing - Animation

Every time you walk into your backyard, you start sneezing, sniffling, and feeling like you want to go back indoors. You're pretty sure you have an allergy, but what are you allergic to? Pollen? Grass? Your neighbor's Golden retriever? The only way to know for sure what's making you sneeze is to have allergy tests at your doctor's office. Let's talk about allergy testing.

Your doctor may do one or more of several different types of allergy tests to see what's causing your allergies. One is a skin test. It can diagnose allergies to things like mold, pollen, animal fur, insect stings, and foods.

With a skin test, your doctor will place a small amount of one substance, or several different substances just under the surface of the skin on your arm or back. You'll feel a little prick when the substances are placed under your skin. After 15 minutes or so, the doctor will look for signs that you're having a reaction. Usually your skin will get red or swollen if you're allergic to something in the test.

Another way to test for allergies is to put a patch of the substance on your skin and leave it there for about 2 days, checking the area every day for any sign of a reaction.

You may have a blood test. A blood test measures the amount of substances called antibodies that your body produces in response to a certain allergen.

If you're allergic to food, you can try avoiding whatever foods you think might be making you sick. This is called elimination testing. Then you add back in each of the foods, one at a time, and look for signs of an allergic reaction.

Your doctor may also try to trigger an allergic reaction in the office by having you eat the food or breathe in the substance you think causes your allergy. This is called a challenge test. The one risk to this test is that, if you're severely allergic, you could have a very serious reaction. Your doctor will watch you very closely during this test to make sure you're safe.

Allergy tests are usually pretty accurate. But sometimes what bothers you in the real world won't show up on the test. If you have one test and it doesn't find your allergy trigger, your doctor may recommend having another type of test. Don't worry if it takes a while to find the source of your allergies. Your doctor will keep trying different methods until you learn exactly what's making you so miserable.

 
 
 
 

 

 
 
 
© 1997-ADAM Company Logo All rights reserved.