Health Library

Anaphylaxis(Anaphylactic Reaction; Severe Allergic Reaction)

Pronounced: ANNA-fill-AX-is

Definition

Anaphylaxis is a severe, sometimes life-threatening, allergic reaction. It affects multiple organs, including the heart and lungs.

It is important to seek medical care right away if you have symptoms of anaphylaxis.

Causes

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
  • Medicines (such as antibiotics, seizure medications, muscle relaxants)
  • Vaccines
  • Latex products (such as gloves, medical tubing, condoms)
  • Blood transfusion
  • Some pain medicines, especially narcotics

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

These factors increase your chance of developing anaphylaxis. Anyone can have anaphylaxis. Tell your doctor if you have any of these risk factors:

  • Previous allergic reaction to the substances listed above, 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 (because of heavy exposure to latex during multiple surgeries)
Symptoms

The symptoms of anaphylaxis usually occur within minutes after exposure to an allergen, but can occur hours later. Symptoms may be mild or very 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, pale/blue skin color, low pulse, dizziness
  • Obstruction of the nose, mouth, and throat
  • Severe respiratory distress (such as chest tightness, shortness of breath, wheezing)
  • Nausea, vomiting, cramping, diarrhea, or abdominal pain
  • Heart arrhythmias
  • Convulsions
  • Low blood pressure
  • Shock
  • Feelings of anxiety
Diagnosis

The doctor will suspect anaphylaxis if you have symptoms and have been exposed to a likely allergen. It is also important to follow up with a doctor who specializes in allergies (allergist/immunologist). The diagnosis of allergy with a risk of anaphylactic reactions is made based on the patient’s history. It is confirmed with skin tests and sometimes blood tests done by allergy specialists.

Treatment

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 medicines—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.

If you are diagnosed with anaphylaxis, follow your doctor's instructions.

Prevention

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 medicine. When possible, ask that medicines be taken as a pill. Allergic reactions can be more severe with injected medicines.
  • Your doctor may give you 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.
  • 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.

RESOURCES:

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

The Food Allergy and Anaphylaxis Network
http://www.foodallergy.org

CANADIAN RESOURCES:

Allergy Asthma Information Association
http://aaia.ca

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

References:

Anaphylaxis. Am Fam Physician. 2003 Oct 1;68(7):1339-1340. Available at: http://www.aafp.org/afp/20031001/1339ph.html. Accessed February 28, 2008.

Anaphylaxis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated September 7, 2012. Accessed November 2, 2012.

Kay AB. Allergy and allergic diseases–second of two parts. N Engl J Med. 2001;344:109-113.

Lieberman P, Kemp SF, et al. The diagnosis and management of anaphylaxis: An updated practice parameter. J Allergy Clin Immunol. 2005 Mar;115(3 Suppl 2):S483-523.

Pumphrey R. Anaphylaxis: can we tell who is at risk of a fatal reaction?. Curr Opin Allergy Clin Immunol. 2004; 4:285.

Sampson, HA, Munoz-Furlong, A, 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;117:391.

Simons E. Anaphylaxis. J Allergy Clin Immunol. 2010;125: S161-81.

Winbery SL, Lieberman PL. Anaphylaxis. Immunol Allergy Clin North Am. 1995;15:447.



Last reviewed September 2013 by Marcin Chwistek, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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