(Anaphylactic Reaction; Severe Allergic Reaction)
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:
- Seizure medicines
- Muscle relaxants
- Opioid pain medicines
- Cancer medicines
- Blood transfusions
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Things that may raise the risk are:
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
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: https://www.dynamed.com/condition/anaphylaxis. Accessed January 29, 2021.
Anaphylaxis. Merck Manual Professional Version website. Available at: http://www.merckmanuals.com/professional/immunology-allergic-disorders/allergic,-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 Last Updated: 3/1/2021