Food Allergy

What is a food allergy?

A
food allergy is when your immune system has a bad 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 a food
allergy?

Your
body’s immune system fights off infections and other dangers to keep you healthy. When
your immune system senses that a food or something in a food is a danger to your health,
you may have a food allergy reaction. Your immune system sends out IgE (immunoglobulin
E) antibodies. These react to the food or substance in the food. Your body releases
histamine and other substances. This can cause hives, asthma, itching in the mouth,
trouble breathing, stomach pains, vomiting, or diarrhea. It does not take much of the
food to cause a severe reaction in highly allergic people.

Most
food allergies are caused by these foods:

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

Food protein-induced enterocolitis syndrome (FPIES) is also called the
delayed food allergy. FPIES often occurs in young babies. It causes vomiting and severe
fluid loss (dehydration). The most common cause of FPIES is having milk, soy, or
grains.

What are the symptoms of a food
allergy?

Allergic symptoms may begin within minutes to an hour after eating the food. Symptoms
may be a bit different for each person. Symptoms may include:

  • Severe
    nausea or vomiting
  • Diarrhea
  • Stomach
    cramps or stomach pain
  • Red,
    itchy rash (hives)
  • Face
    swelling
  • Eczema
  • Itching
    or swelling of the lips, tongue, or mouth
  • Throat
    itching or tightness
  • Feeling
    dizzy with a lowered blood pressure
  • Asthma
    symptoms such as coughing, runny or stuffy nose, wheezing, or trouble breathing

The
symptoms of a food allergy may look like other health problems. Always see your
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, dizzy, lightheaded, or confused (this could be from a drop in
    blood pressure)
  • Nausea, vomiting, or diarrhea
  • Fast
    and weak heartbeat
  • Loss
    of consciousness
  • Seizure

Anaphylaxis is a medical emergency. Call 911 to get help right away. Severe
allergic reactions are treated with epinephrine. You should carry an emergency kit
with self-injecting epinephrine. If you have emergency injectable epinephrine, use it
before you call 911
.

How is a food allergy
diagnosed?

If
you think you have a food allergy, see your healthcare provider for a diagnosis. He or
she will take your health history and do a physical exam. The healthcare provider will
do skin or blood tests or both to find out the exact diagnosis. These tests may
include:

  • Skin
    prick test
  • Blood
    test
  • Oral
    food challenge
  • Trial
    elimination diet