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ACAAI > Patients & Public > Allergies > Anaphylaxis

What Is Anaphylaxis? Arm Yourself with These Facts

  • Anaphylaxis is a life-threatening, often unexpected, allergic reaction that affects many parts of the body at once. Like other allergic reactions, anaphylaxis is the body’s overreaction to a foreign substance that ordinarily is harmless.
  • Symptoms of anaphylaxis include hives, swelling and flushing, difficulty breathing and wheezing, a swelling of the tongue, throat and nose, dizziness and a dangerous drop in blood pressure, nausea and cramping.
  • The symptoms can occur within minutes of exposure to the offending allergen but also can develop after 30 minutes or more. In some cases, a second or biphasic reaction may occur eight to 12 hours after the initial reaction. If symptoms develop quickly, the condition is more likely to be severe and potentially fatal.
  • Patients who have a history of allergic conditions or have had a previous severe reaction are at greater risk for anaphylaxis.
  • Identifying the cause of anaphylaxis requires a detailed history of all food and medication ingested before the reaction and a review of all activities including exercise and sex. While a patient’s history is often the most important tool, skin tests or challenge tests also may be performed to identify specific triggers, confirm a diagnosis or rule out other causes.
  • Allergic reactions to food, latex, medication and insect stings are the most common causes of anaphylaxis. The condition can be triggered by exercise, seminal fluid and there also is a small risk of reaction to allergen imunotherapy.
  • Food allergy accounts for 35% to 55% of anaphylactic reactions with peanuts, tree nuts, fish, milk and eggs being the most common.
  • Up to 6.5% of the general population has a latex sensitivity with health care workers, children with spina bifida and genitourinary abnormalities, and workers with occupational exposures to latex at higher risk.
  • Penicillin is the most common cause of drug-induced anaphylaxis followed by aspirin and non-steroidal anti-inflammatory drugs.
  • If no cause of a reaction is determined, the condition is called idiopathic anaphylaxis.
  • Heart attacks, anxiety disorders, seizure disorders and poisoning are some of the conditions that may be mistaken for anaphylaxis.
  • Immediate emergency treatment is required for all patients who experience any anaphylactic symptoms.

Patients who have had an anaphylactic reaction should see an allergist. An allergist can determine the risk for future reactions, take a detailed history, conduct diagnostic tests, review avoidance techniques and provide instruction on the self-administration of epinephrine.

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