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Anaphylaxis is a severe, generalized allergic reaction. It is estimated that up to 15% of the population is at risk for anaphylaxis*.

What is anaphylaxis?

Anaphylaxis is a severe allergic reaction that involves multiple organ systems (systemic) and can involve the entire body. It can result in difficulty breathing, shock, loss of consciousness,  and even death. It is a medical emergency that always requires immediate medical attention.

What is the mechanism behind anaphylaxis?

Anaphylaxis is triggered the same way as other allergies in that IgE antibodies recognize the allergen and initiate a cascade of immune responses throughout the body.  These immune responses involve the release of histamine and other potent substances that mediate various changes in tissues that lead to the symptoms seen in anaphylaxis.

What causes anaphylaxis?

The most common triggers of anaphylaxis include:

  • Food allergies
  • Drug allergies
  • Insect venom allergies

Other causes of anaphylaxis include latex allergies, and rarely exercise, or exposure to pollens and other inhaled allergens, seminal fluid, hormones and extreme temperatures. Some people have an anaphylactic reaction with no known cause, which is referred to as idiopathic anaphylaxis.

What are the signs and symptoms of anaphylaxis?

Signs and symptoms of anaphylaxis develop rapidly, often within seconds or minutes of exposure to the offending allergen. They may be delayed or self-resolve only to progress an hour later.  They may include the following listed by system:

  • Skin
    • Hives
    • Angioedema, swelling of the eyes, lips or face
    • Bluish skin from lack of oxygen
    • Itchiness
    • Pale skin from shock
    • Skin rash
    • Skin redness or warmth
  • Respiratory
    • Abnormal (high-pitched) breathing sounds
    • Cough
    • Difficulty breathing
    • Fluid in the lungs (pulmonary edema)
    • Hoarse Voice
    • Itching throat
    • Nasal congestion
    • Shortness of breath
    • Throat tightness from swelling (angioedema) in the throat that may be severe enough to block the airway
    • Wheezing
  • Gastrointestinal
    • Abdominal pain or cramping
    • Diarrhea
    • Difficulty swallowing
    • Nausea
    • Vomiting
  • Cardiovascular
    • Abnormal heart rhythm (arrhythmia)
    • Chest pain/tightness
    • Low blood pressure
    • Palpitations
    • Rapid and/or poor pulse
    • Shock
  • Mental State
    • Anxiety
    • Confusion
    • Slurred speech
  • Other
    • Fainting, light-headedness, dizziness
    • Headache
    • Itchy, watering eyes
    • Uterine cramping
    • Weakness

The health care provider will wait to test for the specific allergen that caused anaphylaxis (if the cause is not obvious) until after treatment.

Some drugs such as morphine, x-ray dye, and others may cause an anaphylactic-like reaction (anaphylactoid reaction) when people are first exposed to them. Aspirin may also cause a reaction. These reactions are not the same as the immune system response that occurs with “true” anaphylaxis. However, the symptoms, risk for complications, and treatment are the same for both types of reactions.

How is anaphylaxis treated?

Anaphylaxis is an emergency condition requiring immediate professional medical attention. Call 911 immediately!

Who is at risk for anaphylaxis?

Risks include a history of any type of allergic reaction especially from food allergies, insect venom allergies and drug allergies.   Food allergies account for 35% to 50% of all cases of anaphylaxis**.

Calling your health care provider

Call 911 if you develop severe symptoms of anaphylaxis. If you are with another person, he or she may take you to the nearest emergency room.


  • Avoid triggers such as foods and medications that have caused an allergic reaction (even a mild one) in the past. Ask detailed questions about ingredients when you are eating away from home. Also carefully examine ingredient labels.
  • If you have a child who is allergic to certain foods, introduce one new food at a time in small amounts so you can recognize an allergic reaction.
  • People who know that they have had serious allergic reactions should wear a medical ID tag.
  • If you have a history of serious allergic reactions, carry emergency medications (such as a chewable form of diphenhydramine and injectable epinephrine or a bee sting kit) according to your health care provider’s instructions.
  • Do not use your injectable epinephrine on anyone else. They may have a condition (such as a heart problem) that could be negatively affected by this drug

*American Academy of Allergy, Asthma and Immunology

**The diagnosis and management of anaphylaxis: An updated practice parameter. J Allergy Clin Immunol. 2005; 115:S483-523.

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