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Quick Facts

Food Allergy


The Manual's Editorial Staff

Last full review/revision Jan 2021| Content last modified Jan 2021
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What is a food allergy?

An allergy is when your body's immune system reacts to something harmless, such as food, plants, or medicine. Food allergy is an allergic reaction caused by a certain food.

  • Almost any food can cause an allergic reaction

  • Symptoms of a food allergy include an itchy rash, runny nose, and sometimes wheezing

  • Rarely, a severe allergic reaction to food is life-threatening (such a reaction is called an anaphylactic reaction)

  • Children may outgrow food allergies

  • If adults develop a food allergy, it usually doesn't go away

  • Doctors may do skin and blood tests and try eliminating foods from your diet to find out which food is causing the allergy

What foods cause allergic reactions?

Almost any food can cause an allergic reaction. The most common causes depend on the person's age.

For infants and young children the most common triggers are:

  • Eggs

  • Milk

  • Wheat

  • Peanuts

  • Soybeans

In older children and adults the most common triggers are:

  • Nuts

  • Seafood

What are the symptoms of a food allergy?

In children, food allergy symptoms may change as the child ages.

Babies may show symptoms like:

  • Rash

  • Throwing up

  • Diarrhea

Children 1 year old and older may have:

  • Rash

  • Wheezing (a whistling sound when breathing)

  • Runny nose

By about age 10, food allergies often go away (such as a milk allergy).

In adults and older children, food allergy symptoms may be more severe and can include:

  • Itching in the mouth

  • Hives (red, itchy, slightly raised patches on the skin)

  • Eczema (red, scaly, dry, patchy skin rash, usually where the arms and legs bend)

  • A runny nose and asthma

  • Stomach pain

  • Feeling sick to one’s stomach

  • Cramping and diarrhea

If a food allergy is severe, it may cause an anaphylactic reaction, which can cause a rash over the entire body, throat swelling, and trouble breathing. If not treated, you could die.

How can doctors tell if I have a food allergy?

Your doctor may test for a food allergy in one or more of these ways:

  • Skin prick test, which involves putting a tiny amount of the food on your skin and then poking it with a needle to check for a reaction

  • A blood test

  • Elimination diet, which involves not eating the foods that might be causing the allergy, and then adding them back in one at a time to figure out which food is causing problems

How do doctors treat a food allergy?

The treatment is to avoid eating the food that causes your allergy symptoms. To help with your symptoms, your doctor may have you:

  • Take antihistamine pills for hives and swelling

  • Carry an epinephrine shot to use if you have severe symptoms and to prevent an anaphylactic reaction

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