Food allergy

Allergy to food; Food allergy - peanuts; Food allergy - soy; Food allergy - fish; Food allergy - shellfish; Food allergy - eggs; Food allergy - milk

A food allergy is a type of immune response triggered by eggs, peanuts, milk, shellfish or some other specific food.

Test Your Food Allergy Knowledge

What are common symptoms of food allergies?

	A. Swelling or itching of the face, lips, and tongue
	B. Hives
	C. Wheezing
	D. Hoarse voice
	E. Runny nose
	F. All of the above

Correct Answer

The correct answer is all of the above. Eating something you're allergic to can trigger symptoms ranging from a runny nose to a dangerous full-body reaction. Talk to your doctor if you have any of these symptoms after eating a food, even if it's a small reaction.

Food allergy and food intolerance are the same.

A. True

B. False
Correct Answer
The correct answer is false. A food allergy occurs when your immune system overreacts to a food and releases the chemical histamine. This causes allergic symptoms. Food intolerance is more common and doesn't involve your immune system. Sometimes it occurs because you can't digest part of a food, such as lactose, a type of sugar in milk.

Which is a common food allergy?

	A. Eggs
	B. Fish
	C. Milk
	D. Peanuts
	E. Wheat
	F. All of the above

Correct Answer

The correct answer is all of the above. Any food can cause an allergic reaction, but these are the most common. Other common foods include shellfish, soy, and tree nuts.

If you eat something you're allergic to, your body will react within:

A. 2 minutes

B. 2 hours

C. 24 hours
Correct Answer
The correct answer is two hours. Rarely, the symptoms may begin several hours after eating the food. Mild symptoms, such as a hive on your chin after eating something, will disappear soon and do not require treatment. However, you should tell your doctor about it.
For some people, food allergies can be life-threatening.

A. True

B. False
Correct Answer
The correct answer is true. Some people have a severe allergic reaction, called anaphylaxis. This causes a whole-body reaction. Symptoms can start within minutes and may include breathing and swallowing problems, slurred speech, or passing out. If you have any of these symptoms, call 911 right away.
The only proven treatment for a food allergy is to avoid the food.

A. True

B. False
Correct Answer
The correct answer is true. If you're allergic to a food, the best way to prevent a reaction is to cut the food from your diet. Other treatments, such as allergy shots and probiotics, don't work to treat food allergies.
Many children outgrow their allergy to:

A. Peanuts

B. Shellfish

C. Eggs

D. Tree nuts
Correct Answer
The correct answer is eggs. Many children will outgrow their allergy to eggs, milk, wheat, and soy by the time they are 5 years old if they avoid that food when they are young. Allergies to peanuts, tree nuts, and shellfish tend to last a lifetime.
To find out if you're still allergic to a food, you should eat a small amount.

A. True

B. False
Correct Answer
The correct answer is false. Do not eat a food that caused a reaction in the past without checking with your doctor first. A mild reaction in the past can become a more severe reaction the second or third time you try a food. Your doctor may want to be present when you try the food.
People with food allergies should always carry epinephrine.

A. True

B. False
Correct Answer
The correct answer is true. Epinephrine is a medicine you can carry with you. It can stop a severe allergic reaction and save your life. It comes in a small syringe that is ready for you to give yourself a shot. If you've had an allergic reaction to food -- even a mild reaction -- talk to your doctor about this medicine.
If you begin wheezing after eating a food, you should:

A. Induce vomiting.

B. Call 911 and then inject epinephrine.

C. Inject epinephrine and then call 911.
Correct Answer
The correct answer is to inject epinephrine and then call 911. Make sure you know how to use it. Also show loved ones how to use it in case you can't inject yourself.
Fresh fruits are a common cause of mouth allergies.

A. True

B. False
Correct Answer
The correct answer is true. If you have an allergy to fruits such as melons, apples, pineapple, and other fruits, it can cause your lips, tongue and throat to itch – especially if you eat them raw. The more fruit you eat, the more severe the reaction. A more severe reaction is rare.

Which of the following may prevent food allergies in children?

	A. Avoiding certain foods during pregnancy
	B. Breastfeeding
	C. Introducing the foods during the first year of life

Correct Answer

The correct answer is breastfeeding. Waiting to add allergy-causing foods until your baby is a little older also may help. The timing for this varies from food to food and from baby to baby. Ask your child’s health care provider when is best to start certain foods that commonly cause allergic reactions.

Causes

Many people have a food intolerance. This term usually refers to heartburn, cramps, belly pain, or diarrhea that can occur after they eat foods such as:

Belly pain

Abdominal pain is pain that you feel anywhere between your chest and groin. This is often referred to as the stomach region or belly.

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Corn products
Cow's milk and dairy products (usually due to lactose intolerance)
Lactose intolerance
Lactose is a type of sugar found in milk and other dairy products. An enzyme called lactase is needed by the body to digest lactose. Lactose intoler...
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Wheat and other grains that contain gluten (gluten intolerance or celiac disease)
Celiac disease
Celiac disease is an autoimmune condition that damages the lining of the small intestine. This damage comes from a reaction to eating gluten. This ...
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A true food allergy is much less common.

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.

Allergens

An allergen is a substance that can cause an allergic reaction. In some people, the immune system recognizes allergens as foreign or dangerous. As ...

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In a person with a food allergy, the immune response is oversensitive. When it recognizes an allergen, the immune system launches a response. Chemicals such as histamines are released. These chemicals cause allergy symptoms.

Any food can cause an allergic reaction. The most common food allergies are to:

Eggs (mostly in children)
Fish (older children and adults)
Milk (people of all ages)
Peanuts (people of all ages)
Shellfish such as shrimp, crab, and lobster (people of all ages)
Soy (mostly in children)
Tree nuts (people of all ages)
Wheat (people of all ages)

In rare cases, food additives, such as dyes, thickeners, or preservatives can cause a food allergy or intolerance reaction.

Some people have an oral allergy. This is an allergy type syndrome that affects the mouth and tongue after they eat certain fresh fruits and vegetables:

Melons, apples, pineapple, and other foods contain substances that are similar to certain pollens.
The reaction most often occurs when you eat the raw form of the foods. How severe the reaction is depends on how much of the food you eat.
Unlike true food allergies, people with the oral allergy syndrome rarely develop severe allergic reactions such as anaphylaxis.

Symptoms

Symptoms usually begin within 2 hours after eating. Sometimes, the symptoms begin a longer time after eating the food.

Key symptoms of a food allergy include hives, a hoarse voice, and wheezing.

Other symptoms that may occur include:

Swelling (angioedema), especially of the eyelids, face, lips, and tongue
Angioedema
Angioedema is swelling that is similar to hives, but the swelling is under the skin instead of on the surface. Hives are often called welts. They a...

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Trouble swallowing or breathing due to swelling in the throat
Itching of the mouth, throat, eyes, skin, or any other area
Lightheadedness or fainting
Fainting
Fainting is a brief loss of consciousness due to a drop in blood flow to the brain. The episode most often lasts less than a couple of minutes and y...

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Nasal congestion, runny nose
Stomach cramps, diarrhea, nausea, or vomiting
Stomach cramps
Abdominal pain is pain that you feel anywhere between your chest and groin. This is often referred to as the stomach region or belly.
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Symptoms of mouth (oral) allergy syndrome:

Itchy lips, tongue, and throat
Swollen lips (sometimes)

In a severe reaction, called anaphylaxis, in addition to the above symptoms, you may have low blood pressure and blocked airways. This can be life threatening.

Anaphylaxis

Anaphylaxis is a life-threatening type of allergic reaction.

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Low blood pressure

Low blood pressure occurs when blood pressure is much lower than normal. This means the heart, brain, and other parts of the body may not get enough...

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Exams and Tests

Blood or skin tests are sometimes used to confirm that you have an allergy. A double-blind food challenge is one way to diagnose true food allergies. 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.

Treatment

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

Treatment may involve any of the following:

Avoiding the food (this is the most effective treatment).
Desensitization, during which you eat a small amount of the food each day. This must be done under an allergist's guidance.

Other treatments, including allergy shots and probiotics, have not been proven to help with food allergies.

If your child has a problem with cow's milk formula, your provider may suggest trying a soy-based formula or something called an elemental formula, if it is available.

If you have symptoms on only one area of the body, for example, a hive on the chin after eating the food, you may not need any treatment. The symptoms will likely go away in a brief time. Antihistamines may relieve the discomfort. Soothing skin creams may also provide some relief.

If you have been diagnosed with a food allergy, learn how to use injectable epinephrine. 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 food:

Inject the epinephrine.
Then go to the nearest hospital or emergency facility right away, preferably by ambulance.
If you develop severe allergy symptoms or anaphylaxis, call 911 or the local emergency number.

Support Groups

The following groups can provide more information about food allergies:

American Academy of Allergy Asthma and Immunology -- www.aaaai.org/Conditions-Treatments/Allergies/Food-Allergy
Food Allergy Research and Education (FARE) -- www.foodallergy.org/
National Institute of Allergy and Infectious Diseases -- www.niaid.nih.gov/diseases-conditions/food-allergy

Outlook (Prognosis)

Allergies to peanuts, tree nuts, and shellfish tend to last a lifetime.

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Avoiding the problem foods may be easy if the food is uncommon or easy to identify. When eating away from home, ask detailed questions about the food you are served. When buying food, read package ingredients carefully.

Possible Complications

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Anaphylaxis is a severe, whole-body allergic reaction that is life threatening. Although people with oral allergy syndrome may have an anaphylactic reaction in rare cases, they should ask their provider if they need to carry injectable epinephrine.

Food allergies can trigger or worsen asthma, eczema, or other disorders.

Asthma

Asthma is a chronic disease that causes the airways of the lungs to swell and narrow. It leads to breathing difficulty such as wheezing, shortness o...

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Eczema

Atopic dermatitis is a long-term (chronic) skin disorder that involves scaly and itchy rashes. It is a type of eczema. Other forms of eczema include...

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When to Contact a Medical Professional

Steps to take when a food 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 food.
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.
Anyone who has had an allergic reaction to a food should be seen by an allergist.

Prevention

Breastfeeding may help prevent allergies. Otherwise, there is no known way to prevent food allergies.

A common belief and practice is to delay introducing allergy-causing foods to infants until their gastrointestinal tract has had a chance to mature. The timing for this varies from food to food and from baby to baby.

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

Once an allergy has developed, carefully avoiding the offending food usually prevents further problems.

Open References

References

Bird JA, Burks AW. Food allergy. In: Rich RR, Fleisher TA, Schroeder HW, Weyand CM, Corry DB, Puck JM, eds. Clinical Immunology. 6th ed. Philadelphia, PA: Elsevier; 2023:chap 49.

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

Togias A, Cooper SF, Acebal ML, et al. Addendum guidelines for the prevention of peanut allergy in the United States: report of the National Institute of Allergy and Infectious Diseases-sponsored expert panel. J Allergy Clin Immunol. 2017;139(1):29-44. PMID: 28065278 pubmed.ncbi.nlm.nih.gov/28065278/.

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Allergy testing
Animation

Allergy testing - Animation

myPlate - illustration
The U.S. Department of Agriculture's food guide, called MyPlate, encourages consumers to make healthier food choices. The guide encourages you to make healthy choices and avoid oversized portions. Half your plate should be filled with fruits and vegetables. At least half of your grains should be whole grains. You also should switch to fat-free or low-fat milk.
myPlate
illustration
Anaphylaxis - illustration
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.
Anaphylaxis
illustration
Food allergies - illustration
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.
Food allergies
illustration
Read food labels - illustration
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.
Read food labels
illustration
Antibodies - illustration
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.
Antibodies
illustration

Allergy testing
Animation

Allergy testing - Animation

myPlate - illustration
The U.S. Department of Agriculture's food guide, called MyPlate, encourages consumers to make healthier food choices. The guide encourages you to make healthy choices and avoid oversized portions. Half your plate should be filled with fruits and vegetables. At least half of your grains should be whole grains. You also should switch to fat-free or low-fat milk.
myPlate
illustration
Anaphylaxis - illustration
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.
Anaphylaxis
illustration
Food allergies - illustration
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.
Food allergies
illustration
Read food labels - illustration
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.
Read food labels
illustration
Antibodies - illustration
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.
Antibodies
illustration

A Closer Look

Food allergy

Talking to your MD

Self Care

Tests for Food allergy

Related Information

Immune response
Antibody
Asthma
Atopic dermatitis
Celiac disease – sprue
Lactose intolerance
Asthma in adults - InDepth

Review Date: 11/6/2022

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.

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	A. Induce vomiting.
	B. Call 911 and then inject epinephrine.
	C. Inject epinephrine and then call 911.

	A. True
	B. False

	A. True
	B. False

	A. True
	B. False

	A. Peanuts
	B. Shellfish
	C. Eggs
	D. Tree nuts

Health Library

Food allergy

What are common symptoms of food allergies?

Food allergy and food intolerance are the same.

Which is a common food allergy?

If you eat something you're allergic to, your body will react within:

For some people, food allergies can be life-threatening.

The only proven treatment for a food allergy is to avoid the food.

Many children outgrow their allergy to:

To find out if you're still allergic to a food, you should eat a small amount.

People with food allergies should always carry epinephrine.

If you begin wheezing after eating a food, you should:

Fresh fruits are a common cause of mouth allergies.

Which of the following may prevent food allergies in children?

Causes

Belly pain

Lactose intolerance

Celiac disease

Allergens

Symptoms

Angioedema

Fainting

Stomach cramps

Anaphylaxis

Low blood pressure

Exams and Tests

Treatment

Support Groups

Outlook (Prognosis)

Possible Complications

Asthma

Eczema

When to Contact a Medical Professional

Prevention

References

Allergy testing

myPlate - illustration

myPlate

Anaphylaxis - illustration

Anaphylaxis

Food allergies - illustration

Food allergies

Read food labels - illustration

Read food labels

Antibodies - illustration

Antibodies

Allergy testing

myPlate - illustration

myPlate

Anaphylaxis - illustration

Anaphylaxis

Food allergies - illustration

Food allergies

Read food labels - illustration

Read food labels

Antibodies - illustration

Antibodies

A Closer Look

Talking to your MD

Self Care

Tests for Food allergy

Related Information