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(Anaphylactic Reaction; Severe Allergic Reaction)

How to Say It: ANNA-fill-AX-is


Anaphylaxis is a severe allergic reaction. It can be life threatening. It needs to be treated right away.


Anaphylaxis is caused by the immune system overreacting to allergens or triggers. It is not always known what triggers it. Common triggers are:

  • Foods and food additives, such as:
    • Peanuts, treenuts, and seeds
    • Fish and shellfish
    • Eggs and cow's milk
  • Insect stings or bites from bees, wasps, hornets, yellow jackets, and fire ants
  • Medicines, such as certain types of:
    • Antibiotics
    • Anesthesia
    • Seizure medicines
    • Muscle relaxants
    • Opioid pain medicines
    • Cancer medicines
  • Vaccines
  • Latex
  • Exercise
  • Blood transfusions

Allergic Reaction to Medication (Hives)
Hives Medication

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Risk Factors

Things that may raise the risk are:

  • Previous anaphylaxis
  • Family or personal history of eczema, hay fever, or asthma
  • Exposure to an allergen
  • Certain immune system problems
  • Sensitivity to latex, more common in:
    • Workers who use latex gloves
    • Children with spina bifida
    • Patients exposed to latex gloves or devices from health care


Symptoms often occur within minutes after contact with an allergen. Some may happen hours later. They may be mild or severe enough to cause death. Symptoms may be:

  • Hives and itching
  • Warmth or redness of skin
  • Swelling, redness, stinging or burning—especially on the face, mouth, eyes, or hands
  • Lightheadedness, headache, or pounding heartbeat
  • Pale skin or blue skin color
  • Problems breathing or swallowing
  • Nausea, vomiting, cramping, diarrhea, or belly pain
  • Loss of consciousness


The doctor will ask about your symptoms and health history. A physical exam will be done. This may be enough to make a diagnosis. Blood and urine tests may also be done.

You may be referred to a doctor who treats allergies.


Anaphylaxis needs medical care right away, including:

  • An epinephrine (adrenaline) injection to help:
    • Open airways
    • Narrow blood vessels
    • Stop itching and hives
    • Ease stomach cramps
  • Corticosteroids or antihistamines—to reduce inflammation and improve breathing
  • Bronchodilators—to open airways
  • IV fluids—to help blood pressure
  • Oxygen

Severe anaphylaxis may require:


To reduce the risk of anaphylaxis:

  • Avoid contact with triggers.
  • Ask the doctor about allergy shots.
  • Carry an epinephrine injector at all times.
  • Wear a medical alert bracelet at all times.

American Academy of Allergy, Asthma & Immunology

FARE—Food Allergy Research & Education


Allergy Asthma Information Association

Food Allergy Canada


Anaphylaxis. EBSCO DynaMed website. Available at: Accessed January 29, 2021.

Anaphylaxis. Merck Manual Professional Version website. Available at:,-autoimmune,-and-other-hypersensitivity-disorders/anaphylaxis. Accessed January 29, 2021.

Kelly KJ, Sussman G. Latex allergy: where are we now and how did we get there? J Allergy Clin Immunol Pract. 2017;5(5):1212-1216.

Last reviewed Janaury 2021 by EBSCO Medical Review Board Shawna Grubb, RN