Food Allergies in Children

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 life long.

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 a 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 a food again without a reaction.