Anaphylaxis (pronounced an–a–fi–LAK–sis) is a serious allergic reaction that is rapid in onset and may cause death. This medical emergency requires immediate treatment and then follow-up care by an allergist/immunologist, often referred to as an allergist. Many people may not realize they have an allergy until they experience anaphylaxis. An allergist can examine you and make a proper diagnosis.

Anaphylaxis is triggered when the immune system overreacts to a usually harmless substance (anallergen such as peanut or penicillin) causing mild to severe symptoms that affect various parts of the body. Symptoms usually appear within minutes to a few hours after eating a food, swallowing medication or being stung by an insect. Sometimes symptoms go away, and then return a few hours later, so it is important to get to a hospital (call 911) or seek medical care as soon as an anaphylactic reaction begins and to remain under medical observation for as long as the reaction and symptoms continue.

Symptoms of Anaphylaxis
Symptoms of anaphylaxis may include:

  • Breathing: wheezing, shortness of breath, throat tightness, cough, hoarse voice, chest pain/tightness, trouble swallowing, itchy mouth/throat, nasal stuffiness/congestion
  • Circulation: pale/blue color, low pulse, dizziness, lightheadedness/passing out, low blood pressure, shock, loss of consciousness
  • Skin: hives, swelling, itch, warmth, redness, rash
  • Stomach: nausea, pain/cramps, vomiting, diarrhea
  • Other: anxiety, feeling of “impending doom,” itchy/red/watery eyes, headache, cramping of the uterus

The most dangerous symptoms are low blood pressure, breathing difficulty and loss of consciousness, all of which can be fatal. If you have any of these symptoms, particularly after eating, taking medication or being stung by an insect, seek medical care immediately (call 911). Don’t wait to see if symptoms go away or get better on their own.

Common Causes
Foods: Any food can cause an allergic reaction, but foods that cause the majority of anaphylaxis are peanuts, tree nuts (e.g., walnut, cashew, Brazil nut), shellfish, fish, milk, eggs and preservatives.

Stinging insects: Insect sting venom from yellow jackets, honeybees, paper wasps, hornets and fire ants can cause severe and even deadly reactions in some people.

Medications: Almost any medication can cause an allergic reaction. Common medications that cause anaphylaxis are antibiotics and anti-seizure medicines. Certain post-surgery fluids, vaccines, blood and blood products, radiocontrast dyes, pain medications and other drugs may also cause severe reactions.

Latex: Some products made from natural latex contain allergens that can cause reactions in sensitive individuals. The greatest danger of severe reactions occurs when latex comes into contact with moist areas of the body or internal surfaces during surgery.

Exercise: Although rare, exercise can cause anaphylaxis. Oddly enough, it does not occur after every exercise session and in some cases, only occurs after eating certain foods before exercise.

Treatment and Prevention
If you (or anyone you are with) begin to have an allergic reaction, call for medical help to get to the closest emergency room. The sooner the reaction is treated, the less severe it is likely to become.

Your physician may give an epinephrine (adrenalin) shot to relieve breathing problems and improve circulation, and other medications such as antihistamines (that reduce swelling and itch) or steroids (that further reduce the allergic response).

If you have taken medications and are feeling better, go to the hospital anyway to be sure your reaction is under control.

Once you’ve had an anaphylactic reaction, visit an allergist to get a proper diagnosis. The allergist will take your medical history and conduct other tests, if needed, to determine the exact cause of your reaction. Your allergist can provide information about avoiding the allergen as well as a treatment plan. Avoiding the allergen(s) is the main way to remain safe, but requires a great deal of education. Specific advice may include:

  • Food: how to interpret ingredient labels, manage restaurant dining, avoid “hidden” food allergens
  • Insects: not wearing perfumes, avoiding bright colored clothing and “high risk” activities; wearing long sleeves/pants when outdoors
  • Medications: which drugs/treatments to avoid, a list of alternative medications

In some cases, your allergist may suggest specific treatments, such as allergy shots (or immunotherapy) to virtually eliminate the risk of anaphylaxis from insect stings, or procedures that make it possible to be treated with certain medications to which you are allergic.

Your allergist may also prescribe auto-injectable epinephrine. If so, be sure you understand how and when to use it. Always refill the prescription upon expiration. This medication should be carried with you at all times.

Your allergist may also want you to wear special jewelry that identifies you as having a severe allergy. This ID can provide physicians and others with important information about your medical condition.

If you have had an anaphylactic reaction, inform family, healthcare workers, employers and school staff about your allergy so they can watch for symptoms, help avoid your allergen and develop a treatment plan.

Healthy Tips

  • Anaphylaxis is a serious allergic reaction that comes on quickly, causing at times severe symptoms that affect various parts of the body.
  • The most dangerous symptoms are low blood pressure, breathing difficulty and loss of consciousness, all of which can be fatal.
  • The most common causes of anaphylaxis are foods, medications and insect stings.
  • If you (or anyone you are with) begin to have an allergic reaction, call for medical help to get to the closest emergency room.
  • See an allergist for follow-up care and developing a treatment plan.

Feel Better. Live Better.
An allergist/immunologist, often referred to as an allergist, is a pediatrician or internist with at least two additional years of specialized training in the diagnosis and treatment of problems such as allergies, asthma, autoimmune diseases and the evaluation and treatment of patients with recurrent infections, such as immunodeficiency diseases.

The right care can make the difference between suffering with an allergic disease and feeling better. By visiting the office of an allergist, you can expect an accurate diagnosis, a treatment plan that works and educational information to help you manage your disease.

Find an allergist near you at:

The contents of this brochure are for informational purposes only. It is not intended to replace evaluation by a physician. If you have questions or medical concerns, please contact your allergist/immunologist.

A Trusted Resource
The American Academy of Allergy, Asthma & Immunology (AAAAI) represents allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic disease.

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©2010, American Academy of Allergy, Asthma & Immunology All rights reserved. May not be duplicated or appropriated without permission. Contact



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