Anaphylaxis

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Overview	Symptoms	Treatment	Prevention

Anaphylaxis

Definition

Anaphylaxis is a life-threatening type of allergic reaction.

Alternative Names

Anaphylactic reaction; Anaphylactic shock; Shock - anaphylactic

Causes

Anaphylaxis is an severe, whole-body allergic reaction. After being exposed to a substance like bee sting venom, the person's immune system becomes sensitized to that allergen. On a later exposure, an allergic reaction may occur. This reaction is sudden, severe, and involves the whole body.

Tissues in different parts of the body release histamine and other substances. This causes the airways to tighten and leads to other symptoms.

Some drugs (polymyxin, morphine, x-ray dye, and others) may cause an anaphylactic-like reaction (anaphylactoid reaction) when people are first exposed to them. This is usually due to a toxic reaction, rather than the immune system response that occurs with "true" anaphylaxis.

The symptoms, risk for complications without treatment, and treatment are the same, however, for both types of reactions.

Anaphylaxis can occur in response to any allergen. Common causes include:

Pollens and other inhaled allergens rarely cause anaphylaxis. Some people have an anaphylactic reaction with no known cause.

Anaphylaxis rarely occurs. However, it is life-threatening and can occur at any time. Risks include past history of any type of allergic reaction.

References

The diagnosis and management of anaphylaxis: an updated practice parameter. J Allergy Clin Immunol. 2005 Mar;115(3 Suppl):S483-523.

Sicherer SH, Simons FE, Section on Allergy and Immunology, American Academy of Pediatrics. Self-injectable epinephrine for first-aid management of anaphylaxis. Pediatrics. 2007;119:638-646.

Simons FE. Anaphylaxis. J Allergy Clin Immunol. 2008;121:S402-S407.

Sampson HA, Muñoz-Furlong A, Campbell RL, Adkinson NF Jr, Bock SA, Branum A, et al. Second symposium on the definition and management of anaphylaxis: summary report-second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. Ann Emerg Med. 2006; 47:373-380.


Shock


Allergic reactions


Anaphylaxis


Hives


Food allergies


Insect stings and allergy


Allergic reactions to medication


Antibodies

Review Date: 4/28/2008
Reviewed By: David C. Dugdale, III., MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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