Definition and Overview

Anaphylaxis is a severe form of allergic reaction that can lead to death unless immediate medical attention is provided. It occurs when the immune system releases a large amount of chemicals in response to an allergen, causing the body to go into shock. It can develop within a few minutes or even seconds of exposure, and causes severe and life-threatening symptoms such as the narrowing of the airways, obstructed breathing, and a sudden drop in blood pressure. An anaphylactic attack can be treated with a shot of epinephrine, which controls the symptoms and prevents complications.

Causes of Condition

The immune system protects the body from foreign substances, such as viruses and bacteria, by producing antibodies and releasing chemicals to fight them off.

However, in the case of anaphylaxis, the immune system overreacts to a particular allergen, causing severe allergy symptoms that can potentially send the body into shock.

There is another form of anaphylaxis called anaphylactoid reaction. This is not caused by the release of allergy antibodies but linked to exercise (particularly aerobic activities) and contrast dye materials used in certain imaging scan. If a patient does not have any known allergies and the cause of the symptoms cannot be identified; the case will be diagnosed as idiopathic anaphylaxis.

The following are the common triggers and risk factors of anaphylaxis:

Common Triggers

The specific cause of anaphylaxis may differ depending on what a person is allergic to. The most common allergens linked to these severe attacks include:

  • Some medications, namely penicillin, aspirin, ibuprofen, morphine, and naproxen
  • Peanuts or tree nuts such as pecans, walnuts, cashews, and almonds
  • Wheat
  • Fish
  • Shellfish
  • Milk
  • Eggs
  • Insect stings from wasps, hornets, or fire ants, among others
  • Bee venom
  • Latex

Risk Factors

  • Family history of allergies or severe allergic reactions
  • Asthma
  • Allergic atopic eczema
  • Previous history of anaphylaxis - A person who has had an anaphylactic attack in the past faces a higher risk of another or a more severe attack.

Key Symptoms

Since anaphylaxis is an allergic reaction, its early symptoms may be similar to that of mild allergic reaction. While mild reactions usually go away without treatment or with over-the-counter antihistamine medications, anaphylactic reactions require emergency medical treatment.

The common symptoms of allergic reactions that also present in anaphylactic cases include:

The more telltale signs of anaphylaxis are:

  • Flushed or pale skin
  • Feeling a lump in the throat
  • Constricted airways causing trouble breathing
  • Swollen tongue
  • Swollen throat
  • Wheezing
  • Weak yet rapid pulse
  • Dizziness
  • Fainting
  • Stomach cramps
  • Anxiety
  • Palpitations
  • Slurred speech

These symptoms typically begin within 5 minutes of exposure to the allergen but can also present themselves 30 minutes after exposure. If the reaction begins as mild allergies, it may take up to an hour for a person to determine that the reaction is anaphylactic. Thus, it is best not to rule an allergic reaction out as mild or normal and observe the symptoms closely as reactions can worsen or escalate into anaphylactic shock pretty quickly.

Who to See and Types of Treatments Available

If a person is having or is suspected of having an anaphylactic reaction, he or she should be brought to the emergency room immediately, where he will be given an epinephrine injection. This treatment is used for both anaphylaxis and anaphylactoid reactions.

In some cases, patients may require a long-term treatment plan for managing severe allergic reactions. These cases should be brought to the attention of an allergist or immunologist.

Patients who are prone to having severe allergic reactions are sometimes given an epinephrine autoinjector by their attending physician. This can be used in cases of an anaphylactic attack. A single shot of an autoinjector, such as EpiPen or EpiPen Jr. can help control the symptoms and prevent complications or threat to life while on the way to the emergency room. Nevertheless, a patient given a shot of an epinephrine autoinjector should still be brought to the emergency department to help prevent recurrences.

Despite its potentially fatal effects, anaphylaxis deaths are rare. Patients usually make a full recovery after receiving prompt treatment.


  • Lieberman PL. Recognition and first-line treatment of anaphylaxis. Am J Med. 2014;127:S6-S11.

  • Lieberman PL, Nicklas RA, Oppenheimer J, and the Joint Task Force on Practice Parameters of the American Academy of Allergy, Asthma and Immunology; American College of Allergy, Asthma and Immunology; and Joint Council of Allergy, Asthma and Immunology. The diagnosis and management of anaphylaxis practice parameter: 2010 update. J Allergy Clin Immunol. 2010;126:477-480.

  • Schwartz LB. Systemic anaphylaxis, food allergy, and insect sting allergy. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 261.

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