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 05:00 PM

Pediatric Allergy & Immunology

The Clinical Immunology Division evaluates recurrent infections, and suspected or confirmed immunodeficiency disorders. Our Miami location also evaluates HIV and fevers of unknown origin.

Learn more

Related Videos

What are the symptoms of a food allergy?

Dr. Amy Feldman is an allergist and immunologist with Nicklaus Children’s Hospital. In this video she gives a quick overview of the most common allergic reactions to food allergy.

Learn more about

Insect Bites

Insect bites and stings are bites/stings into the skin that cause an allergic/or toxic reaction locally or systemically. While most reactions are localized and mild, they can on occasion result in severe/life-threatening problems. Learn more

Shellfish Allergy

Shellfish allergy is when you have an allergic reaction to crab, lobster, shrimp, oysters, scallops, clams, or other shellfish. Learn more

Peanut Allergy

Peanut allergy is one of the most common food allergies found among children, exposure to even a tiny amount of peanuts can cause potentially severe and life-threatening symptoms for children with peanut allergy. Learn more