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Food Allergies

What is a food allergy?

A food allergy is an abnormal response of the body to a certain food. It is important to know that this is different than a food intolerance, which does not affect the immune system, although some of the same symptoms may be present.

What causes a food allergy?

Before having a food allergy reaction, a sensitive child must have been exposed to the food at least once before, or could also be sensitized through breast milk. It is the second time your child eats the food that the allergic symptoms happen. At that time, when IgE antibodies react with the food, histamines are released, which can cause your child to experience hives, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, and/or diarrhea.

What is the difference between food allergy and food intolerance?

Food allergy causes an immune system response, causing symptoms in your child that range from uncomfortable to life threatening. Food intolerance does not affect the immune system, although some symptoms may be the same as in food allergy.

What foods most often cause food allergy?

Eggs, milk, and peanuts are the most common causes of food allergies in children, with wheat, soy, and tree nuts also included. Peanuts, tree nuts such as almonds and walnuts, fish and shellfish commonly cause the most severe reactions. These foods make up approximately 90% of all food allergies.

Nearly 3 percent of children have food allergies. Although most children "outgrow" their allergies, allergy to peanuts, tree nuts, and shellfish may be life-long.

What are the symptoms of food allergy?

Allergic symptoms may begin within minutes to an hour after ingesting the food. The following are the most common symptoms of food allergy. However, each child may experience symptoms differently. Symptoms may include:
  • vomiting
  • diarrhea
  • cramps
  • hives
  • swelling
  • eczema
  • itching or swelling of the lips, tongue, or mouth itching or tightness in the throat
  • difficulty breathing
  • wheezing
  • lowered blood pressure
According to the National Institute of Allergy and Infectious Disease, it does not take much of the food to cause a severe reaction in highly allergic people. In fact, as little as 1/44,000 of a peanut kernel can cause an allergic reaction for severely allergic individuals.

The symptoms of food allergy may resemble other problems or medical conditions. Always consult your child's physician for a diagnosis.

Treatment for food allergy: There is no medication to prevent food allergy. The goal of treatment is to avoid the foods that cause the symptoms. After seeing your child's physician and finding which foods your child is allergic to, it is very important to avoid these foods and other similar foods in that food group. If you are breastfeeding your child, it is important to avoid foods in your diet that your child is allergic to. Small amounts of the food allergen may be transmitted to your child through your breast milk and cause a reaction.

It is also important to give vitamins and minerals to your child if he/she is unable to eat certain foods. Discuss this with your child's physician.

For children who have had a severe food reaction, your child's physician may prescribe an emergency kit that contains epinephrine, which helps stop the symptoms of severe reactions. Consult your child's physician for further information.

Some children, under the direction of his/her physician, may be given certain foods again after 3 to 6 months to see if he/she has outgrown the allergy. Many allergies may be short term in children and the food may be tolerated after the age of 3 or 4.

Milk and soy allergy: Allergies to milk and soy are usually seen in infants and young children. Often, these symptoms are unlike the symptoms of other allergies, but, rather, may include the following:
  • colic (fussy baby)
  • blood in your child's stool
  • poor growth
Often, your child's physician will change your baby's formula to a soy formula or breast milk if it is thought he/she is allergic to milk. If your child has problems with soy formula, your child's physician might change him/her to an easily digested hypoallergenic formula.

The symptoms of a milk or soy allergy may resemble other problems or medical conditions. Always consult your child's physician for a diagnosis.

Prevention of food allergies: The development of food allergies cannot be prevented, but can often be delayed in infants by following these recommendations:
  • If possible, breastfeed your infant for the first 6 months.
  • Do not give solid foods until your child is 6 months of age or older.
  • Avoid cow's milk, wheat, eggs, peanuts, and fish during your child's first year of life.

Washington University allergy and asthma specialists see patients at 3 locations:

South County:
11124 South Towne Square, 200, 2
St. Louis, MO 63123
314-996-8670
Fax: 314-996-3085

Central West End:
Center for Advanced Medicine - Lung Center
4921 Parkview Place, B, 8
St. Louis, MO 63110
(314) 454-8917

West County:
Barnes-Jewish West County Hospital
Medical Building Two
10 Barnes West Drive, 200
Creve Coeur, MO 63141
(314) 996-8670
Fax: 314-996-3195

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Copyright 2014 Washington University School of Medicine
Copyright 2014 Washington University School of Medicine