• Anaphylaxis

    (Anaphylactic Reaction; Severe Allergic Reaction)


    Anaphylaxis is a severe, sometimes life-threatening, allergic reaction. It affects multiple organs, including the heart and lungs.
    It is important to seek emergency medical care right away if you have symptoms of anaphylaxis.


    Substances that cause anaphylaxis are often called allergens or triggers. Common triggers include:
    • Foods and food additives, especially eggs, peanuts, seafood, cow's milk, soy, fish, shellfish, seeds, and tree nuts
    • Insect stings or bites from bees, wasps, hornets, yellow jackets, and fire ants
    • Medications such as antibiotics (especially penicillin), medications used in anesthesia, seizure medications, and muscle relaxants
    • Exercise
    • Vaccines
    • Latex products such as gloves, medical tubing, and condoms
    • Blood transfusions
    Allergic Reaction to Medication (Hives)
    Hives Medication
    Copyright © Nucleus Medical Media, Inc.
    Some triggers, like dyes used in x-ray procedures, can cause a reaction similar to anaphylaxis.

    Risk Factors

    Anyone can have anaphylaxis. Factors that may increase your risk of anaphylaxis include:
    • Previous allergic reaction to an allergen, even if it is a mild reaction
    • History of eczema, hay fever , or asthma
    • Children who have certain conditions, such as spina bifida and urogenital defects may be at increased risk for latex allergy due to heavy exposure to latex during multiple surgeries


    The symptoms of anaphylaxis usually occur within minutes after exposure to an allergen, but can occur hours later. Symptoms may be mild or severe, including death. They include:
    • Hives and itching
    • Warmth or redness of skin
    • Swelling, redness, stinging or burning, especially on the face, mouth, eyes, or hands
    • Lightheadedness and pale/blue skin color
    • Chest tightness, shortness of breath, difficulty breathing, and wheezing
    • Nausea, vomiting, cramping, diarrhea , or abdominal pain
    • Loss of consciousness


    The diagnosis of allergy with a risk of anaphylactic reactions is made based on the person's history. Anaphylaxis will be suspected if you have symptoms and have been exposed to a likely allergen. It is important to see a doctor who specializes in allergies. Skin tests and sometimes blood tests can done by allergy specialists to confirm the cause of the reaction.


    Anaphylaxis is a medical emergency that requires immediate medical treatment, including:
    • Epinephrine (adrenaline) injection—Makes blood vessels constrict, relaxes the airway, stops itching and hives, and relieves gastrointestinal cramping.
    • Other medications—Corticosteroids and/or antihistamines may be given after the epinephrine to decrease inflammation and improve breathing.
    • Bronchodilators—To improve breathing.
    • IV fluids—To maintain blood pressure.
    • Oxygen
    • Cardiopulmonary resuscitation (CPR)—May be necessary in severe cases when anaphylaxis leads to cardiovascular collapse. Severe anaphylaxis may require mechanical ventilation until swelling is brought under control.
    Note : If you receive emergency epinephrine, you should go to the emergency room right away, even if your symptoms have gone away.


    Avoiding substances that trigger anaphylaxis is the best prevention. In addition:
    • Allergy shots can decrease the risk of anaphylaxis and reduce the severity of the reactions to certain triggers.
    • Wear a medical alert bracelet that lists your allergies.
    • Tell your doctor or dentist about your allergies before taking any medication. When possible, ask that medications be taken as a pill. Allergic reactions can be more severe with injected medications.
    • Your doctor may give you a self-injectable epinephrine kit to keep with you at home, work, in the car, and when you travel. Be sure family and friends know how to use the kit too. Get training from your doctor and practice using it in the doctor's office.
    • Make sure your epinephrine kit is not expired.
    • Avoid any exercise that triggers a reaction. In some cases, exercise-induced anaphylaxis can be triggered by food or specific food allergies. Stop exercising at the first sign of a reaction.
    • Make sure the school nurse and teachers know about any allergies your child has. If your child has self-injectable epinephrine, make sure school staff knows how to use it and understand when it is needed.
    • If you are allergic to insect stings, wear protective clothing when outside.
    • Always remain in the doctor or dentist's office 30 minutes after you have an injection. Report any symptoms right away.


    American Academy of Allergy, Asthma & Immunology http://www.aaaai.org

    FARE—Food Allergy Research & Education https://www.foodallergy.org


    Allergy Asthma Information Association http://aaia.ca

    Calgary Allergy Network http://www.calgaryallergy.ca


    Anaphylaxis. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T113858/Anaphylaxis. Updated August 22, 2017. Accessed October 2, 2017.

    Anaphylaxis. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/immunology-allergic-disorders/allergic,-autoimmune,-and-other-hypersensitivity-disorders/anaphylaxis. Updated June 2016. Accessed October 2, 2017.

    Arnold JJ, Willimas PM. Anaphylaxis: recognition and management. Am Fam Physician. 2011;84(10):1111-1118.

    Sampson, HA, Munoz-Furlong, A, Campbell, 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. J Allergy Clin Immunol. 2006;117(2):391-397.

    Simons E. Anaphylaxis. J Allergy Clin Immunol. 2010;125(2 Suppl 2): S161-S181.

    Revision Information

    • Reviewer: EBSCO Medical Review Board Marcin Chwistek, MD
    • Review Date: 09/2017
    • Update Date: 09/10/2014
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