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Allergic Reaction or Anaphylaxis: Signs, Symptoms and Treatment

August 2013

The Cause of an Allergic Reaction

What exactly triggers food allergies in children? Food allergy is an abnormal immune system response to food protein.

The first time a child with food allergies is exposed to the offending food protein, his body is tricked into thinking the protein is harmful. The child's immune system responds by creating disease-fighting antibodies called immunoglobulin E (or IgE). This response is an attempt to drive out the protein from the body.

Every time the child eats the same food after that, the antibodies immediately recognize it and release histamine and other chemicals into the bloodstream, which produces an allergic reaction.

Symptoms of an Allergic Reaction

If your child's food-allergic friend develops an itchy rash in reaction to consuming cow's milk, don't assume a reaction in your child will present itself the same way, even if they are allergic to the same food. No two food-allergic children are alike and neither are their allergic reactions.

Some children will break out in hives, develop a runny nose or experience abdominal pain, while others will develop a reaction called anaphylaxis a severe and sometimes life-threatening allergic reaction that can involve multiple body organs. Not all food-allergic children will experience the same symptoms, which may appear within a few minutes to several hours after eating the offending food. Symptoms might even vary from one allergic reaction to the next. Most reactions tend to last under a day and have an effect on skin, the gastrointestinal (digestive) system, the respiratory (lung function and breathing) system and/or the cardiovascular (heart function and blood pressure) system.

In some instances, reactions are delayed for several days. Examples of delayed reactions include eczema, an itchy rash, or conditions like eosinophilic disorders that cause gastrointestinal symptoms. These reactions may be caused by a mechanism that does not always involve IgE. We are still learning about how these work.


Typically involving several body systems, anaphylaxis is an allergic reaction that can be mild to severe and may be fatal. Children with asthma are at greater risk for anaphylaxis.

The first signs of an anaphylactic reaction may include a warm or flushed feeling, tingling in the mouth or a red and itchy rash or hives. Additional symptoms may include light-headedness, shortness of breath, severe sneezing, anxiety, stomach cramps, and vomiting and diarrhea. Airway constriction, drop in blood pressure, rapid pulse, dizziness or loss of consciousness can present in certain cases. A dangerous drop in blood pressure can result in anaphylactic shock.

Anaphylactic symptoms can occur from minutes to several hours after ingestion. Usually symptoms appear immediately after a child consumes the offending food and warrant urgent emergency treatment.

red cross, medical alert

Signs of Anaphylaxis1

Skin: Flushing; itching; hives; swelling; rash; itching of lips, tongue and palate; swelling of lips, tongue and back of throat (uvula); itching around eyes; redness and swelling of eyes; and tearing of eyes.

Respiratory: Itching and tightness of the throat; difficulty swallowing; change in voice; hoarseness; dry cough; harsh high-pitched breathing (stridor); itching in the outer ear canals; shortness of breath; chest tightness; cough and wheezing; itching of the nose; runny nose; congestion; and sneezing.

Gastrointestinal: Nausea; cramping abdominal pain; vomiting; and diarrhea.

Cardiovascular: Decreased blood pressure; feeling faint; fainting; not acting normally; chest pain; and heart rhythm abnormalities.

Other: Uterine cramping in women; and an aura of impending doom.


It is imperative to take measures to avoid anaphylaxis by steering clear of food that causes these symptoms. But that can prove challenging even your greatest attempts to remove offending foods from your child's diet may fall short. Your child might inadvertently reach for another child's snack, come into contact with an “unsafe” food at the lunch table or take a cookie that's mistakenly offered to him. Accidental exposures to food allergens happen despite the utmost care parents take to avoid them.

Allergic reactions can be unpredictable and subsequent allergic reactions can result in anaphylaxis even if prior reactions were minor. So you, your child and your child's care providers must always be prepared to react immediately to treat anaphylaxis. Having emergency medicines available at all times and a written emergency care plan is the best way to be prepared to treat an allergic reaction.

If your child has been diagnosed with severe allergies, he has likely been prescribed injectable epinephrine, such as EpiPen® Auvi-Q™ , Adrenaclick™ or generic epineprhine autoinjector. This lifesaving medication must enter the bloodstream quickly, so your child should carry his auto-injector with him everywhere at home, school, relatives’ and friends’ houses, restaurants, etc.

Consider having your child wear emergency medical identification in the event he has an allergic reaction outside of your care.
Whenever your child uses his EpiPen® Auvi-Q™ , Adrenaclick™ or generic epineprhine autoinjector, you MUST call for emergency response, such as dialing 911, to transport your child to an emergency room for monitoring and further treatment.

There are two important reasons for seeking emergency care: sometimes a single dose of epinephrine is not enough to stop an anaphylactic reaction. And, in some cases, a second flare up of symptoms (known as a biphasic reaction) develops which demands further treatment. As with any emergency, an allergic reaction requires prompt recognition and treatment.

Related Resources

KFA's Starter Guide to Parenting a Child with a Food Allergy

On Trial This free 47-page e-book is filled with essential information for parenting a food-allergic child, including:
  • Understanding Food Allergies and Anaphylaxis
  • Diagnosis and Treatment
  • Nutrition Information and Dietary Concerns
  • Grocery Shopping and Label Reading
  • And much more!

1. Sampson, et al. (2005). Symposium on the Definition and Management of Anaphylaxis: Summary report. Journal of Allergy and Clinical Immunology, 115(3), 584-591.

Approved by KFA's Medical Advisory Team October 2009. Updated August 2013.

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Page last updated 7/29/2012

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