Anaphylaxis

Also known as: anaphylactic shock, anaphylaxis shock, anaphylactic reaction.

What causes anaphylaxis?

Anaphylaxis is an acute life threatening allergic reaction with symptoms from many body systems.

What causes anaphylaxis? 

When the body’s immune system responds to a foreign substance in a previously sensitized child, it does so by rapidly releasing a variety of inflammatory and other chemicals (histamines, tryptase, heparin, prostaglandins, leukotrienes, cytokines and platelet-activating factor) from a blood cells called mast cells and basophils.

In anaphylaxis, these substances commonly give rise to abnormalities of the skin, cardiovascular (heart and blood vessels), respiratory (airways and lungs) and gastrointestinal (gut) systems.

In children food allergies (like milk, eggs, wheat, soy, peanuts, tree nuts,  sea foods, preservatives in food, medications (antibiotics and preservatives), insect stings, blood/ blood products and others are common causes of anaphylaxis. Sometimes no cause is found. Environmental triggers like dust mites, pollens and molds are not usual causes of anaphylaxis.

What are the signs/symptoms of anaphylaxis?

Anaphylaxis involves a wide range of signs and symptoms. These may develop slowly (usually when substances are taken by mouth) over hours, or may progress rapidly in minutes.

Signs/symptoms include:

  • hives
  • pale skin
  • wheezing and trouble breathing
  • swelling/itchy/watery eyes
  • feeling flushed (hot)
  • swelling of the tongue
  • mouth and face
  • heart problems like a fast weak heartbeat, and a low blood pressure which can go on to heart failure and death.

Anaphylaxis may also be accompanied by persistent gut symptoms like abdominal cramp-like pain, vomiting and/or diarrhea. These symptoms may last for many hours (32hrs) in spite of treatments given.

What are anaphylaxis care options?

Avoidance of the allergens (triggering substances) that produce anaphylaxis is the best approach to preventing it from occurring.

Severe cases will require early use of epinephrine (Epi-pen) by injection, stabilizing the airway, breathing and circulation (the ABC’s of Cardiopulmonary Resuscitation -CPR), fluids given intravenously (or into the marrow of a bone), and other supportive care as needed (e.g. oxygen, antihistamines, and corticosteroids).


Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: May 05, 2021 11:44 AM

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