Anaphylaxis: Recognition and Management


Am Fam Physician. 2020 Sep 15;102(6):355-362.

  Patient information: A handout on this topic is available at

Author disclosure: No relevant financial affiliations.

Anaphylaxis is a life-threatening systemic reaction, normally occurring within one to two hours of exposure to an allergen. The incidence of anaphylaxis in the United States is 2.1 per 1,000 person-years. Most anaphylactic reactions occur outside the hospital setting. Urticaria, difficulty breathing, and mucosal swelling are the most common symptoms of anaphylaxis. The most common triggers are medications, stinging insect venoms, and foods; however, unidentified triggers occur in up to one-fifth of cases. Coexisting asthma, mast cell disorders, older age, underlying cardiovascular disease, peanut and tree nut allergy, and drug-induced reactions are associated with severe or fatal anaphylactic reactions. Clinicians can obtain serum tryptase levels, reflecting mast cell degranulation, when the clinical diagnosis of anaphylaxis is not clear. Acute management of anaphylaxis involves removal of the trigger; early administration of intramuscular epinephrine; supportive care for the patient's airway, breathing, and circulation; and a period of observation for potential biphasic reactions. Only after epinephrine administration should adjunct medications be considered; these include histamine H1 and H2 antagonists, corticosteroids, beta2 agonists, and glucagon. Patients should be monitored for a biphasic reaction (i.e., recurrence of anaphylaxis without reexposure to the allergen) for four to 12 hours, depending on risk factors for severe anaphylaxis. Following an anaphylactic reaction, management should focus on developing an emergency action plan, referral to an allergist, and patient education on avoidance of triggers and appropriate use of an epinephrine auto-injector.

Anaphylaxis is a severe allergic reaction that occurs quickly and can be fatal. The incidence of anaphylaxis in the United States between 2004 and 2016 was 2.1 per 1,000 person-years, with one-fourth of anaphylactic reactions affecting children younger than 17 years.1  Most anaphylactic reactions occur outside the hospital setting (Table 1),2,3 and most individuals go to the hospital or emergency department for treatment.2,4 In the United States, the incidence of anaphylaxis peaks in children two to 12 years of age and in adults between 50 and 69 years of age.1 One out of 20 of all anaphylaxis cases may require hospitalization1,2; in the United States, hospitalizations for anaphylaxis have steadily increased over the past 10 years.5 The annual number of confirmed anaphylaxis-related deaths in the United States ranges from 186 to 225.5 The average fatality rate is 0.3% for most hospitalizations or emergency department presentations for anaphylaxis.5 Risk factors for severe or fatal anaphylaxis include coexisting asthma, mast cell disorders, age older than 50 years, underlying cardiovascular disease, peanut and tree nut allergy, and drug-induced reactions.610


One out of 20 of all anaphylaxis cases requires hospitalization; in the United States, hospitalizations for anaphylaxis have steadily increased over the past 10 years.

Gastrointestinal and respiratory symptoms of anaphylaxis are more likely to be overlooked in children. Only 55% of health care professionals recognize anaphylaxis without cutaneous involvement.

One-half of patients presenting to the emergency department who meet the National Institute of Allergy and Infectious Diseases/Food Allergy and Anaphylaxis Network diagnostic criteria for anaphylaxis receive treatment with epinephrine.

The Authors

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MATTHEW C. PFLIPSEN, MD, is a candidate in the Masters of Health Professions Education program and an assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences, Bethesda, Md....

KARLA M. VEGA COLON, MD, FAAFP, is the officer in charge and medical director of the Madigan Army Medical Center Family Medicine Residency Program, Tacoma, Wash.; an assistant professor in the Department of Family Medicine at the Uniformed Services University of the Health Sciences; and a clinical instructor in the Department of Family Medicine at the University of Washington, Seattle.

Address correspondence to Matthew C. Pflipsen, MD, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814 (email: Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.


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