What is a food allergy?
A food allergy is a reaction by the body's immune system to
something you ate or drank. Food allergies are more common
in young children and in people who have other allergies,
such as hay fever and eczema (dry skin rash). Food
allergies must be taken seriously. Very tiny amounts of a
food can cause a reaction if you are allergic to it, and a
severe reaction can be sudden and life threatening.
How does it occur?
A food allergy occurs when the body's immune system
mistakenly believes that a harmless substance (a food) is
harmful. In order to protect the body, the immune system
creates substances called antibodies to that food. The next
time you eat that particular food, your immune system
releases huge amounts of chemicals, such as histamines, to
protect the body. These chemicals trigger symptoms that can
affect the respiratory and cardiovascular systems,
gastrointestinal tract, and skin.
The foods that most often cause allergic reactions are:
- cow's milk
- eggs
- peanuts
- nuts
- seafood, especially shellfish
- wheat
- soy
- peas
- beans
- tomatoes
- spices
- fresh fruit.
People who have asthma have an increased risk of a severe or
fatal reaction.
What are the symptoms?
Reactions differ. They may occur right away or not for
several hours. Symptoms may be mild, or they might be life
threatening when the allergy causes breathing problems.
Symptoms may include:
- skin rash or hives
- itching
- swelling in the lips, face, throat, or other part of the
body
- vomiting
- diarrhea
- stomach cramps
- wheezing or trouble breathing
- coughing
- trouble swallowing
- throat tightness or closing
- red, watery eyes
- fainting
- sense of doom
- dizziness
- change of voice.
The symptoms of a severe reaction generally occur within
minutes to 2 hours after contact with the food causing the
reaction. In rare instances symptoms may occur up to 4
hours later.
How is it diagnosed?
Your health care provider will ask about your symptoms and
the foods you eat. If your symptoms are not severe, your
provider may suggest that you try to find which foods cause
your symptoms by not eating certain foods for a while. Then
you can carefully try eating these foods again, one by one,
to see if your symptoms come back. Ask your provider which
foods you should avoid at first.
Your health care provider may recommend that you keep a food
diary. This involves recording all of the food you eat and
when you eat it. You should also record any symptoms you
may have.
If your symptoms are severe and there is no obvious cause,
then it may be possible to have allergy skin tests for
common food allergies such as egg, cow's milk, nuts,
and shellfish.
How is it treated?
There is no cure for food allergy. Strict avoidance of
foods you are allergic to is the only way to prevent a
reaction.
If you have sudden, severe food allergy symptoms or your
symptoms do not get better and you start having throat
tightness or trouble breathing, call 911 for emergency help.
For severe reactions, you may need a shot of epinephrine.
Mild symptoms may not need treatment. Or your health care
provider may prescribe antihistamines for you to use as
needed. For moderate symptoms your provider may also
prescribe a steroid medicine for you to use for a short
time.
If you have had one or more severe reactions to food, ask
your provider if you should carry injectable epinephrine
(EpiPen) with you. A shot with the EpiPen given by yourself
or a friend can slow down a severe reaction while you wait
for medical help to arrive.
How long will the effects last?
The effects of the allergic reaction last from several
minutes to hours, depending on how much of the food you ate
and the severity of your allergy.
Some food allergies are outgrown while others are lifelong.
Most children who are allergic to milk, eggs, soy, and wheat
outgrow their allergies. However, allergies to peanuts,
nuts, fish, and shellfish are almost never outgrown.
How can I take care of myself and help prevent an allergic
reaction to food?
- The only way to not have a reaction is to avoid the food
that causes the allergy symptoms. When you know you are
allergic to a specific food, you should avoid eating that
food. Be sure to check the ingredients on food package
labels and ask about the ingredients in foods prepared in
restaurants when you eat out.
- Follow all of your health care provider's instructions.
- Keep track of all reactions for yourself and your health
care provider.
- Substitute soy-based products for milk if you are
allergic to milk but not to soy.
- If you tend to have severe food allergy reactions, you
should ask your health care provider about carrying
medicine with you, such as injectable epinephrine
(EpiPen), for emergency use. Tell others about your
allergy; that is, what you need to avoid, the symptoms
of an allergic reaction, and how they can help during an
allergic emergency.
- Wear a medical ID bracelet or necklace that notes your
allergy.
- For more information, contact:
The Food Allergy & Anaphylaxis Network (FAAN)
Phone: (800) 929-4040
Web site: http://www.foodallergy.org.


Disclaimer: This content is reviewed periodically and is subject to
change as new health information becomes available. The
information provided is intended to be informative and educational and is not a
replacement for professional medical evaluation, advice, diagnosis or
treatment by a healthcare professional.
HIA File ALL3109F.HTM Release 9.0/2006. Copyright © 2006 McKesson Corporation and/or one of its subdiaries. All Rights Reserved.
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