Anaphylaxis is a severe, sudden, and potentially fatal allergic reaction
to a foreign substance or antigen that affects multiple systems of the
Anaphylaxis is a severe, whole-body allergic reaction. After initial
exposure to a substance such as wasp sting toxin, the allergic
child's immune system becomes sensitized to that allergen. On a
subsequent exposure to the specific allergen, an allergic reaction, which
can involve a number of different areas of the body, occurs. Anaphylaxis
is thought to result from antigen-antibody interactions on the surface of
mast cells, connective tissue cells that are believed to contain a number
of regulatory, or mediator, chemicals. Specifically, an immunoglobulin
antibody protein, IgE, is produced in response to the presence of the
allergen. IgE binds to the mast cells, causing them to suddenly release a
number of chemicals, including histamine, heparin, serotonin, and
bradykinin. Once released, these chemicals produce the bodily reactions
that characterize anaphylaxis: constriction of the airways, causing
wheezing and difficulty in breathing; and gastrointestinal symptoms, such
. Shock can occur when the released histamine causes the blood vessels to
dilate, which lowers blood pressure; histamine also causes fluids to leak
from the bloodstream
EpiPen Jr., a syringe containing a child's dosage of
adrenaline, is used for the emergency treatment of anaphylactic
(© Mark Thomas/Photo Researchers, Inc.)
into the tissues, lowering the blood volume. Pulmonary edema can result
from fluids leaking into the alveoli (air sacs) of the lung.
Substances that can trigger an anaphylactic reaction include:
Anaphylactoid (meaning "anaphylactic-like") reactions are
similar to those of true anaphylaxis but do not require an IgE immune
reaction. These are usually caused by direct stimulation of the mast
cells. The same chemicals as with anaphylaxis are released, with the same
effects, so the symptoms are treated the same way. However, an
anaphylactoid reaction can occur on initial exposure to an allergen as
well as on subsequent exposures, since no sensitization is required.
There is also a rare kind of food allergy, called exercise-induced
allergy, that is caused by eating a specific food and then exercising. It
, and anaphylaxis. The offending food does not cause a reaction without
, and, alternately, exercise does not cause a reaction without ingesting
the food beforehand.
Although likely an underestimate, about 10,000 cases of anaphylaxis occur
per year in North America, with about 750 fatalities a year. The exact
prevalence of anaphylaxis is unknown, because milder reactions may be
attacks or sudden cases of hives, and more serious or fatal episodes
might be reported as heart attacks, as the initial symptoms of hives,
asthma, and swollen throat can fade quickly.
Causes and symptoms
The symptoms of anaphylaxis may occur within seconds of exposure, or be
delayed 15 to 30 minutes and sometimes even an hour or more later, if the
allergen is aspirin or other similar drugs. The sooner the symptoms occur
after exposure, the more severe the anaphylactic reaction is likely to be.
The first symptoms of an anaphylactic reaction are associated with the
skin: flushing (warmth and redness), itching (often in the groin or
armpits), and hives. These symptoms are often accompanied by
; a rapid, irregular pulse; and a sense of impending doom. Then the throat
and tongue swell, the voice becomes hoarse, and swallowing and breathing
become labored. Symptoms of
or asthma may also occur, causing a runny nose, sneezing, wheezing, and
abnormal high-pitched breathing sounds, further worsening the breathing
problems. Gastrointestinal effects may also develop, including vomiting,
diarrhea, and stomach cramps. The child may be confused and have slurred
speech. In about 25 percent of the cases, the chemicals flooding the blood
stream will cause a generalized opening of capillaries (tiny blood
vessels), resulting in a drop in blood pressure, lightheadedness, and even
a loss of consciousness, which are typical symptoms of anaphylactic shock.
The child may exhibit blueness of the skin (cyanosis), lips, or nail beds.
After the original symptoms occur, there are three possible outcomes:
The child should be given immediate emergency care, if possible, and then
taken to the emergency room or the local emergency number (e.g., 911)
should be called if symptoms of anaphylaxis develop.
A child having an anaphylactic reaction will exhibit typical symptoms of
anaphylaxis, such as hives and swelling of the eyes or face, blue skin
from lack of oxygen, or pale skin from shock. The airway may be blocked,
and the child may be wheezing as well as confused and weak. The pulse will
be rapid and the blood pressure may be low. Anaphylaxis is an emergency
condition that requires immediate professional medical attention.
Once a child has had an anaphylactic reaction, an allergist should be
consulted to identify the specific allergen that caused the reaction. The
allergist will take a detailed medical history and use blood or skin tests
to identify the allergen. The allergist will ask about activities that the
child participated in before the event, food and medications the child may
have ingested, and whether the child had contact with any rubber products.
Because of the severity of these reactions, treatment must begin
immediately. The most common emergency treatment involves injection of
epinephrine (adrenaline) to stop the release of histamines and relax the
muscles of the respiratory tract. The injection is given in the outer
thigh and can be administered through light fabric such as trousers,
skirts, or stockings. Heavier clothing may have to be removed prior to the
injection. After the injection, emergency services or 911 should be called
immediately. A child with known severe allergic reactions should be
carrying an allergy kit with epinephrine; if not, treatment will have to
be delayed until emergency personnel can provide the required medication.
For reactions to insect stings or allergy shots, a tourniquet should be
placed between the puncture site and the heart; the tourniquet should be
released every 10 minutes. If the child is conscious, he or she should lie
down and elevate the feet. If trained, the parents or others present
should administer CPR if the child stops breathing or does not have a
pulse. After 10 to 15 minutes, if symptoms are still significant, another
dose of epinephrine can be injected. Even after the reaction subsides, the
child should still be taken to the emergency room immediately and
monitored for three to four hours, since symptoms can redevelop. Other
treatments may be given by medical personnel, including oxygen,
intravenous fluids, breathing medications, and possibly more epinephrine.
The epinephrine may make the child feel shaky and have a rapid, pounding
pulse, but these are normal side effects and are only dangerous to those
with heart problems. Steroids and
may also be given but are usually not as helpful initially as
epinephrine. However, they may be useful in preventing a recurrent delayed
If the child is being treated with beta blocker medications commonly used
to treat high blood pressure, angina, thyroid disorders, migraines, or
glaucoma, it may be difficult to reverse an anaphylactic reaction.
Anaphylaxis is a severe disorder that has a poor prognosis without prompt
treatment. Symptoms are usually resolved with appropriate therapy;
therefore, immediate emergency care is essential.
For children with known reactions to
, foods, insect stings, specific foods, or any of the allergens that can
induce an anaphylactic reaction, avoidance of the symptom-inducing agent
is the best form of prevention.
Specific avoidance measures that are recommended include:
In addition, children with a history of allergic reactions should carry an
emergency kit containing injectable epinephrine and chewable antihistamine
and be instructed in its use. A child who is not prepared to deal with an
anaphylactic reaction is at an increased risk of dying. The allergy kit
should include simple instructions on when and how to use the kit;
sterilizing swabs to cleanse the skin before and after the injection;
epinephrine in a preloaded syringe, as prescribed by the childs doctor in
doses appropriate for children; and antihistamine tablets. The expiration
date on the medications in the allergy kit should be checked and
medications replaced as needed. Also, the epinephrine solution should be
clear; if it is pinkish brown, it should be discarded and replaced.
There are many brands of allergy kits. The simplest kit to use is the
Ana-kit, which contains a sterile syringe preloaded with two doses of
epinephrine with a stop between. Another commonly used kit is the Epi-Pen,
which carries a single self-injecting, spring-loaded syringe of
epinephrine. Two Epi-Pen kits should be carried, so that two doses are
available. Allergy kits should be kept at home, school, and
; and the school administrator, teachers, and friends should be made aware
of the childs allergies. Adults associated with the child should be
trained in giving an injection and have a plan to transport the child to
the hospital. Older children should be taught to give self-injections.
Children at risk for anaphylaxis should also wear a Medic Alert bracelet
or necklace or carry a medical emergency card with them at all times that
clearly describes their allergy.
A consultation with an allergist can help to identify the substances that
trigger the reaction; the allergist can also provide information on how to
best avoid the triggering substance. The allergist may also be able to
give allergy shots to children with wasp, yellow jacket, hornet, honey
bee, or fire ant allergies. These shots provide 90 percent protection
against the first four insect reactions, but less protection against fire
ant reactions. Premedication is also helpful in preventing anaphylaxis
from x-ray dyes; also there may be alternative dyes available for use that
are less likely to cause reactions. Desensitization to medications has
also been successful in some cases. The process involves gradually
increasing the amount of medication given under controlled conditions. The
procedure has worked for sensitivities to penicillin, sulfa drugs, and
The risk of anaphylaxis sometimes diminishes over time if there are no
repeated exposures or reactions. However, the child at risk should also
expect the worst and be prepared with preventive medication.
—A foreign substance that provokes an immune reaction or allergic
response in some sensitive people but not in most others.
—A hypersensitivity reaction in response to exposure to a
—A hormone produced by the adrenal medulla. It is important in
the response to stress and partially regulates heart rate and
metabolism. It is also called adrenaline.
Immunoglobulin E (IgE)
—A type of protein in blood plasma that acts as an antibody to
activate allergic reactions. About 50% of patients with allergic
disorders have increased IgE levels in their blood serum.
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Experts on Raising Your Food-Allergic Child.
New York: Owl Books, 2001.
Coss, Linda Marienhoff.
How to Manage Your Childs Life-Threatening Food Allergies: Practical
Tips for Daily Life.
Lake Forest, CA: Plumtree Press, 2004.
Anaphylaxis: A Practical Guide.
London, UK: Butterworth-Heinemann, 2004.
Allie the Allergic Elephant: A Childrens Story of Peanut Allergies.
San Francisco: Jungle Communications, 2002.
American Academy of Allergy, Asthma, and Immunology.
611 E. Wells Street, Milwaukee, WI 53202. Web site:
Food Allergy and Anaphylaxis Network.
10400 Eaton Place, Suite 107, Fairfax, VA 220302208. Web site:
American College of Allergy, Asthma, and Immunology.
Available online at
(accessed October 10, 2004).