What is food allergy in children?

A food allergy is when your child’s body has a bad immune reaction to a certain food. This is different from a food intolerance which does not affect the immune system. This is true even though some of the same signs may be present.

What causes food allergy in a child?

Your child’s immune system fights off infections and other dangers to keep him or her healthy. Food allergy occurs when your child’s immune system decides that a food is a “danger” to your child’s health. The reason this happens isn’t clear. Your child’s immune system sends out immunoglobulin E (or IgE) antibodies. These antibodies react to the food and cause the release of histamines and other chemicals. These chemicals can cause hives, asthma, itching in the mouth, trouble breathing, stomach pains, vomiting, or diarrhea. It doesn’t take much of the food to cause a severe reaction in highly allergic children.

Most food allergies are caused by these foods:

  • Milk
  • Eggs
  • Wheat
  • Soy
  • Tree nuts
  • Peanuts
  • Fish
  • Shellfish

Eggs, milk, and peanuts are the most common causes of food allergies in children. Although many children “outgrow” their allergies, some food allergies may be lifelong.

Discuss your child’s food allergies with his or her allergy healthcare provider.

What are the symptoms of food allergy in a child?

Allergic symptoms may start within minutes to an hour after eating the food. Symptoms can occur a bit differently in each child. They can include:

  • Severe nausea or vomiting
  • Diarrhea
  • Stomach cramps or stomach pain
  • Red, itchy rash (hives)
  • Swelling of the face
  • Eczema
  • Itching or swelling of the lips, tongue, or mouth
  • Itching or tightness in the throat
  • Dizziness, with lowered blood pressure
  • Asthma symptoms, such as coughing, runny or stuffy nose, wheezing, or trouble breathing
  • A feeling of impending doom

It doesn’t take much of the food to cause a very bad reaction in highly allergic children. In fact, a tiny piece of a peanut or a small sip of milk can cause a severe reaction in a child that is highly allergic.

Some babies may have non-life-threatening, delayed allergies to milk, soy, or other allergens. These symptoms often are not like the symptoms of other allergies. Instead, they may include:

  • Colic or fussy behavior
  • Blood in your child’s stool
  • Poor growth
  • Severe eczema that doesn’t go away.

These non-life-threatening allergies may look like other health problems and are often hard to diagnose with allergy testing. Make sure your child sees his or her healthcare provider for a diagnosis.

Severe symptoms of a food allergy

Anaphylaxis is a severe allergic reaction. It is life-threatening. Symptoms can include:

  • Trouble breathing, shortness of breath, or wheezing
  • Feeling as if the throat is closing
  • Hoarseness or trouble talking
  • Swelling of the face, lips, tongue, and throat
  • Cool, moist, or pale blue skin
  • Feeling faint, lightheaded, or confused
  • Nausea, vomiting, or diarrhea
  • Fast and weak heartbeat
  • Feeling dizzy, with a sudden drop in blood pressure
  • Loss of consciousness
  • Seizure

Anaphylaxis is a medical emergency. If you suspect your child is having anaphylaxis, call 911 to get help right away. If your child has an epinephrine autoinjector, use it while you are waiting for the ambulance to arrive. Epinephrine will help stop the symptoms of the allergic reaction. It is life-saving when used for severe allergic reactions. Your child should always have 2 epinephrine autoinjectors with them wherever they go.

How is food allergy diagnosed in a child?

Your child’s healthcare provider will make the diagnosis based on a physical exam and a thorough health history. This history should include a list of foods that were eaten before the allergic symptoms.

The healthcare provider will do some tests to make an exact diagnosis. These tests may include the following.

Skin prick test

Skin prick tests are the most common allergy tests. Skin tests measure if there are IgE antibodies to specific allergens such as foods, pollens, or animal dander. A small amount of diluted allergen is put on the skin. The area is pricked or scratched. If a child is allergic to the allergen, a small raised bump that looks like a mosquito bite appears after about 15 minutes. Testing for many allergens may be done at the same time. Skin test results are available right away after the testing is done. Skin prick testing may not be done if your child very recently had a severe reaction, or if he or she has long-term (chronic) hives or severe eczema.

Blood tests

Blood tests for allergies measure IgE antibodies to specific allergens in the blood. The blood test that is most commonly used is called RAST (radioallergosorbent test). Blood tests may be used when skin tests can’t be done or if there are still questions about a food allergy after the skin test. A positive blood test does not always mean that your child has a specific allergy. Any positive blood test needs to be explained by a healthcare provider who is familiar with the tests and knows your child’s health history. These tests take longer to get results. They may be more costly than other allergy tests.

Note: Neither skin nor a blood test can determine how severe an allergic reaction will be.

Food challenge test

This test is given by an allergist. He or she gives your child a very small amount of an allergen by mouth. The allergen can also be inhaled. Then your child is watched closely for any reaction. Food challenges are most often done if the allergist thinks your child will be able to eat food again without a reaction.

How is food allergy treated in a child?

There is currently no medicine to prevent food allergies in children. The goal of treatment is to stay away from the foods that cause the symptoms. It’s very important that your child not eat these foods or other similar foods in that food group. If you are breastfeeding your child, talk to your child’s allergist about whether or not you need to avoid these foods too.

It may be important to give vitamins to your child if he or she is unable to eat certain foods. Discuss this with your child’s healthcare provider.

Children with food allergies who are at risk of a severe reaction (anaphylaxis) should carry 2 epinephrine autoinjectors at all times. This helps stop the symptoms of severe reactions. Your child’s healthcare provider can teach you how to use it.

Some children may outgrow their allergies. Your child’s healthcare provider will discuss follow up testing or food challenges with you. Many allergies may be short-term in children. Your child may be able to eat the food after age 3 or 4. Reintroduce a food only after discussing it with your child’s healthcare provider. This is because of the risk of a severe reaction.

If your baby is allergic to milk, treatment may include changing your baby’s formula to a soy formula. If your child has problems with soy formula, your child’s healthcare provider might suggest an easily digested hypoallergenic formula.

What can I do to prevent food allergies in my child?

For many years, it was recommended to delay giving a child certain highly allergenic foods until after age 1 year. But new research shows that for babies at high risk of developing peanut allergy, giving them peanuts between 4 to 6 months can greatly lower the risk for peanut allergy.

Babies are considered “high risk” if they have moderate to severe eczema or egg allergy. Other children who may be at risk include children with food allergies other than egg allergies and those with siblings with peanut allergies. But these lower-risk babies were not included in the recent studies.

If your child is at high risk for peanut allergy, talk with your child’s healthcare provider before giving them peanuts. A blood test or skin test for peanuts may be advised first.

If your child does not have eczema or other food allergies, you can introduce peanuts at a time that you think is appropriate.

There is no evidence that breastfeeding or formula feeding gives more protection against food allergies. If you are breastfeeding, you don’t need to stay away from any particular foods unless your healthcare provider tells you to. Give your baby only infant formula or breastmilk until age 1. Don’t give your baby whole milk until after age 1.

Giving your baby eggs early may help prevent egg allergy. Giving other foods early isn’t helpful to prevent allergies. But adding foods to a baby’s diet within the first year of life is important.

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