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Food Allergies

What is food allergy?

A food allergy is an abnormal response of the body's immune system to certain foods. This is not the same as food intolerance, although some of the symptoms may be very similar.

What causes food allergies?

A person must be exposed to the food at least once before the allergic symptoms happen. At that time, the immune system releases IgE antibodies that react to the food. Histamines are released. These cause allergy symptoms such as hives, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, or diarrhea.

Which foods most often cause food allergies?

About 90% of all food allergies are caused by 8 foods, that include:

  • Milk

  • Eggs

  • Wheat

  • Soy

  • Tree nuts

  • Fish

  • Shellfish

  • Peanuts

Some facts about food allergies:

  • Eggs, milk, and peanuts are the most common causes of food allergies in children

  • Peanuts, tree nuts, fish, and shellfish commonly cause the most severe reactions.

  • Nearly 5% of children under the age of 5 years have food allergies.

  • From 1997 to 2007, food allergies increased 18% among children under age 18 years.

  • Most children "outgrow" their allergies, however, allergies to peanuts, tree nuts, and shellfish may be lifelong.

  • According to the National Institute of Allergy and Infectious Diseases, it doesn't take much food to cause a severe allergic reaction—1/44,000 of a peanut can cause a severe reaction in a highly allergic person.

What are the symptoms of food allergies?

Allergic symptoms may begin within minutes to an hour after eating the food. The following are the most common symptoms of a food allergy. However, each person may experience symptoms differently. Symptoms may include:

  • Swelling, itching of lips and mouth

  • Tightness in the throat or hoarse voice

  • Nausea and vomiting

  • Diarrhea and cramps

  • Hives, or itchy, raised bums

  • Swelling of the skin

  • Itching

The symptoms of a food allergy may look like other medical conditions or problems. Always talk with your healthcare provider for a diagnosis.

What are severe symptoms of food allergy?

Anaphylaxis is a severe allergic reaction. It is life-threatening. Symptoms can include those above as well as the following:

  • Trouble breathing or wheezing

  • Feeling as if the throat is closing or that the lips and tongue are swelling

  • Flushing of the skin

  • Itching of palms, soles of feet

  • Feeling faint

  • Nausea

  • Fast pulse

  • Low blood pressure

  • Loss of consciousness

Anaphylaxis is a medical emergency. Call 911 for immediate medical assistance. Severe allergic reactions are treated with epinephrine. Those with known severe allergies should carry emergency kits with self-injecting epinephrine or Epi-pens.

Treatment for food allergies in adults

The goal of treatment is to avoid the food that causes the allergic symptoms. There is no medicine to prevent food allergies, although research is ongoing.

You need to be prepared should you eat something with the food that causes your allergic reaction. You may need an emergency kit to stop severe reactions. Make sure you talk with your healthcare provider about what you should do.

There are medicines available for some symptoms caused by food allergy after the food has been eaten. Discuss available medicines with your healthcare provider.

Treatment of food allergies in children

As in adults, it is very important to avoid these foods that cause allergies. If you are breastfeeding your child, it is important that you discuss with your child's healthcare provider whether it is necessary to avoid foods to which your child is allergic.

You may need to give vitamins to your child if he or she is unable to eat certain foods. Discuss this with your child's healthcare provider.

Your child's healthcare provider may also prescribe an emergency kit. Be sure to ask your child's healthcare provider about an emergency kit if you don't already have one.

Some children under the supervision of their healthcare provider, may be given certain foods after some period of avoidance. This determines whether or not the child has outgrown the allergy.

Online Medical Reviewers:

  • Berry, Judith, PhD, APRN
  • Blaivas, Allen J., DO
  • Jarvinen-Seppo, Kirsi MD, PhD