Anaphylaxis (an–a–fi–LAK–sis) is a serious allergic reaction that typically comes on quickly 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. If warranted, your doctor will prescribe injectable epinephrine to use in an emergency.
Anaphylaxis is triggered when the immune system overreacts to a usually harmless substance (an allergen 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.
Anaphylaxis requires immediate medical treatment, including an injection of epinephrine and a trip to a hospital emergency room. If it isn’t treated properly, anaphylaxis can be fatal. Sometimes symptoms go away, and then return a few hours later, so it is important to take these steps 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.
Foods: Any food can cause an allergic reaction, but foods that cause the majority of anaphylaxis are peanuts, tree nuts (such as 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, use your autoinjectable epinephrine and get to the closest emergency room. The sooner the reaction is treated, the less severe it is likely to become. 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 immunotherapy (allergy shots) 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 autoinjectable 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.
• 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 an allergist, you can expect an accurate diagnosis, a treatment plan that works and educational information to help you manage your disease.
The AAAAI's Find an Allergist / Immunologist service is a trusted resource to help you find a specialist close to home.
Find out more about anaphylaxis.
Podcast Episode: Anaphylaxis Update: What's New in the 2020 Practice Parameter
Marcus Shaker, MD, MS, FAAAAI, discusses the recently published anaphylaxis practice parameter. Listen now to learn about updates to the parameter and important discussion points surrounding biphasic anaphylaxis and use of steroids or antihistamines in the management of anaphylaxis. This is practical, thorough, and extremely useful for anyone who cares for patients at risk for anaphylaxis—and patients themselves. (August 12, 2020)
Click here to listen to the podcast.
Read the transcript of the conversation.
Anaphylaxis Practice Parameter
This article has been reviewed by Andrew Moore, MD, FAAAAI