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Anaphylaxis
is a severe, potentially life-threatening allergic response
that is marked by swelling, hives, lowered blood pressure,
and dilated blood vessels. In severe cases, a person
will go into shock. Blood pressure drops severely and
swelling occurs in the bronchial tissues of the lungs,
causing the person to choke and lose consciousness.
If anaphylactic shock isn't treated immediately, it
can be fatal.
This
condition occurs when the immune system creates specific
disease-fighting antibodies (called immunoglobulin E
or IgE) toward a substance that is normally harmless,
such as food. When you are first exposed to the substance,
your body does not react, but it does produce the antibodies.
When you are exposed to the substance again, the antibodies
spring into action, releasing large amounts of a protein
called histamine. Histamine causes the symptoms described
above.
What
Are the Symptoms of Anaphylaxis?
Anaphylaxis
may begin with severe itching of the eyes or face and,
within minutes, progress to more serious symptoms. These
include swelling (which can cause swallowing and breathing
difficulty), abdominal pain, cramps, vomiting, diarrhea,
hives and angioedema (hives in the throat).
If
you have symptoms of anaphylaxis, seek emergency medical
attention immediately, as the condition can quickly
result in an increased heart rate, sudden weakness,
a drop in blood pressure, shock, and ultimately unconsciousness
and death.
What
Are the Common Triggers of Anaphylaxis?
Food
is generally the most common cause of anaphylaxis. Common
food triggers include peanuts, tree nuts (almond, walnut,
hazel, Brazil, and cashews), shellfish (shrimp, lobster),
dairy products, egg whites, and sesame seeds. Wasp or
bee stings are also common causes of anaphylaxis.
Exercise
can also trigger anaphylaxis if the activity occurs
after eating allergy-provoking food.
Pollens
and other inhaled allergens (allergy-causing substances)
rarely cause anaphylaxis.
Some
substances can cause reactions -- called anaphylactoid
reactions -- that are similar to and just as serious
as anaphylaxis, but do not involve immunoglobulin E
antibodies. Common causes are fish, latex, and some
medications, such as penicillin.
How
Is Anaphylaxis Diagnosed?
Anaphylaxis
is diagnosed based on its symptoms. People with a history
of allergic reactions may be at greater risk for developing
a severe reaction in the future.
Skin
testing may help confirm the substances that cause severe
allergic reactions. However, this type of test may not
be recommended if you have reason to suspect that you
will have an anaphylactic reaction to the substance.
How
Is Anaphylaxis Treated?
There
is only one effective treatment for anaphylaxis -- epinephrine
by injection. Epinephrine is adrenaline and it rapidly
reverses anaphylactic symptoms. It is typically given
through an automatic injection device. The most common
injection site is the thigh.
If
you are near someone who is going into anaphylactic
shock, call for professional medical help immediately.
CPR and other lifesaving measures may be required.
In
addition to epinephrine, treatment for shock includes
intravenous fluids and medicines that support the actions
of the heart and circulatory system. After a person
in shock is stabilized, antihistamines may be given
to further reduce symptoms.
How
Can I Be Prepared?
If
you are allergic to bee stings or any substances that
cause anaphylaxis, you should always be prepared. Ask
your doctor to prescribe an epinephrine injection kit
and carry it with you at all times.
Also,
it's important that you inform your healthcare provider
of any drug allergies before undergoing any type of
medical treatment, including dental care.
It
is also a good idea to wear a MedicAlert bracelet or
pendant, or carry a card that identifies your allergy.
In cases of emergency, it could save your life.
Reviewed
by the doctors at The Cleveland Clinic Department of
Pulmonary, Allergy and Critical Care Medicine.
Edited
by Charlotte E. Grayson, MD, Feb. 2004, WebMD.
Portions
of this page © The Cleveland Clinic 2000-2004
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