Managing Allergic Reactions and Anaphylaxis in the Emergency Department
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Management of Allergic Reactions and Anaphylaxis in the Emergency Department (Pharmacology CME)

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Table of Contents

About This Issue

A patient with an allergic reaction can present with symptoms ranging from mild rash, to gastrointestinal complaints, to complete respiratory collapse. Predicting which patients are likely to suffer moderate to severe allergic and/or anaphylactic reactions can be difficult, though noting history and risk factors for severity will dictate treatment plans. In this issue, you will review:

How the diagnosis of anaphylaxis and allergic reactions are defined and graded by criteria from national and international organizations.

The ways augmenting factors, concomitant diseases, and co-factors can increase or worsen allergic reactions.

The prevalence of certain anaphylaxis signs and symptoms of skin, respiratory, gastrointestinal, cardiovascular, and neurologic systems.

The latest evidence on administering epinephrine: dosage, routes, and monitoring, including special cautions on intravenous dosing.

Fluids, corticosteroids, antihistamines: is there any evidence they are helpful?

Unusual types of reactions to watch for: alpha-gal (tick-borne) allergy, scombroid poisoning, and Kounis syndrome.

The risk factors for biphasic anaphylactic reaction and whether observation can help reduce risk.

Disposition recommendations for mild, moderate, and severe anaphylaxis as well as nonanaphylactic reactions.

Table of Contents
  1. About This Issue
  2. Abstract
  3. Case Presentations
  4. Introduction
  5. Critical Appraisal of the Literature
    1. Criteria for Diagnosis of Anaphylaxis
    2. Criteria for Diagnosis of Acute Allergic Reactions
  6. Pathophysiology and Epidemiology
    1. Pathophysiology
    2. Epidemiology and Common Triggers
      1. Risk Factors
      2. Onset
      3. Duration
      4. Biphasic Reaction
  7. Differential Diagnosis
  8. Prehospital Care
  9. Emergency Department Evaluation
    1. History
    2. Physical Examination
  10. Diagnostic Studies
  11. Treatment
    1. Anaphylaxis Management
      1. Airway Protection
      2. Epinephrine
        • Intramuscular Epinephrine
        • Intravenous Epinephrine
      3. Decontamination
      4. Intravenous Fluids
      5. Corticosteroids
      6. Antihistamines
      7. Bronchodilators
      8. Vasopressors
      9. Glucagon
    2. Non–anaphylactic Allergic Reaction Management
      1. Antihistamines for Non–anaphylactic Allergic Reactions
        • Extended Allergic Reactions and Chronic Urticaria
  12. Special Populations and Circumstances
    1. Alpha-gal Allergy
    2. Scombroid Poisoning
    3. Kounis Syndrome
  13. Controversies and Cutting Edge
  14. Disposition
    1. Low-Risk, Resolved Anaphylaxis
    2. High-Risk, Mild to Moderate Anaphylaxis
    3. Severe Anaphylaxis
    4. Non-anaphylactic Allergic Reaction
  15. Summary
  16. Risk Management Pitfalls for Managing Allergic Reactions and Anaphylaxis in the Emergency Department
  17. Time- and Cost-Effective Strategies
  18. 5 Things That Will Change Your Practice
  19. Case Conclusions
  20. Clinical Pathway for Managing Allergic Reactions and Anaphylaxis in the Emergency Department
  21. Tables and Figures
  22. References


An acute allergic reaction is a rapid-onset, IgE-mediated hypersensitivity reaction. Although it is most commonly caused by food, insect stings, and medications, there are many additional causes. Symptoms can range from mild urticaria and swelling, to abdominal cramping, to respiratory collapse. Anaphylaxis and anaphylactic shock are the most severe, life-threatening forms of allergic reaction, with fast onset and decompensation, requiring urgent airway monitoring and support. This issue reviews the current evidence on managing allergy and anaphylaxis with epinephrine, and reviews the evidence on corticosteroids, antihistamines, and other adjunctive therapies. Guidelines are reviewed to offer assistance with grading of symptoms, which can help determine treatment and disposition. Biphasic reactions and allergic reactions caused by alpha-gal, scombroid poisoning, and Kounis syndrome are also reviewed.

Case Presentations

You are called to the resuscitation bay, where you see a young woman who is struggling to breathe…
  • She is in obvious respiratory distress, with stridor, wheezing, and a widespread urticarial rash. Her vital signs are stable except for mild tachycardia.
  • The patient’s friend at the bedside is tearful, worrying that she may have accidentally given the patient food that contained peanuts.
  • You wonder how aggressive you should be in managing this patient‘s symptoms and whether she should be given epinephrine, antihistamine, and/or corticosteroids . . .
A young man arrives complaining of persistent nausea and abdominal cramping for the last 30 minutes…
  • The 30-year-old previously healthy patient reports having eaten some tuna sushi. You start to think about gastroenteritis or food poisoning, when he asks if this could be an allergic reaction to the tuna.
  • His vital signs are all within normal limits.
  • You wonder if this could be an allergic reaction, and whether you should ask the resident to call the health department…
When you circle back to the first patient you treated 4 hours ago, you note that her blood pressure has dropped, and she is somnolent...
  • On your previous re-evaluations, you noted some improvement in the young woman‘s symptoms, but now you notice that her stridor and rash have returned. In addition to her somnolence, her blood pressure is now 80/40 mm Hg.
  • You treat her with the same medications as earlier, but her symptoms do not improve.
  • You wonder what is happening, and what your next steps should be . . .

How would you manage these patients? Subscribe for evidence-based best practices and to discover the outcomes.

Clinical Pathway for Managing Allergic Reactions and Anaphylaxis in the Emergency Department

Clinical Pathway for Managing Allergic Reactions and Anaphylaxis in the Emergency Department

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Tables and Figures

Table 6. Differential Diagnosis for Allergic Reactions
Table 2. Clinical Criteria for Diagnosing Anaphylaxis (World Allergy Organization, 2020)
Table 3. Severity Grading System for Acute Allergic Reactions
Table 4. Grading System for Generalized Hypersensitivity Reactions
Table 5. Factors Influencing Allergic Reactions

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Key References

Following are the most informative references cited in this paper, as determined by the authors.

1. * Rowe B, Gaeta T. Anaphylaxis, allergies, and angioedema. In: Tintinalli J, Stapczynski J, Ma O, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 8th ed: McGraw-Hill; 2016:74-79. (Textbook chapter)

3. * Long B, Gottlieb M. Emergency medicine updates: anaphylaxis. Am J Emerg Med. 2021;49:35-39. (Review) DOI: 10.1016/j.ajem.2021.05.006

6. * Campbell RL, Li JTC, Nicklas RA, et al. Emergency department diagnosis and treatment of anaphylaxis: a practice parameter. Ann Allergy Asthma Immunol. 2014;113(6):599-608. (Literature search, practice parameter) DOI: 10.1016/j.anai.2014.10.007

8. * Sampson HA, Muñoz-Furlong A, Campbell RL, 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. Ann Emerg Med. 2006;47(4):373-380. (Symposium guidelines) DOI: 10.1016/j.jaci.2005.12.1303

10. * Cardona V, Ansotegui IJ, Ebisawa M, et al. World Allergy Organization anaphylaxis guidance 2020. World Allergy Organ J 2020;13(10):100472-100472. (Systematic review, guidelines) DOI: 10.1016/j.waojou.2020.100472

16. * Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis—a 2020 practice parameter update, systematic review, and grading of recommendations, assessment, development and evaluation (grade) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123. (Systematic review) DOI: 10.1016/j.jaci.2020.01.017

53. U.S. Food and Drug Administration. Vistaril® (hydroxyzine pamoate) capsules and oral suspension. 2014. Accessed June 10, 2022. (FDA drug package insert)

54. U.S. Food and Drug Administration. Zyrtec® (ceterizine hydrochloride) tablets and syrup for oral use. 2002. Accessed June 10, 2022. (FDA drug package insert)

55. U.S. Food and Drug Administration. Claritin® brand of loratidine tablets, syrup, and rapidly-disintegrating tablets. 2000. Accessed June 10, 2022. (FDA drug package insert)

Subscribe to get the full list of 68 references and see how the authors distilled all of the evidence into a concise, clinically relevant, practical resource.

Keywords: allergy, anaphylaxis, urticaria, alpha-gal, biphasic, epinephrine, corticosteroids, antihistamines, glucagon, scombroid, Kounis

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Publication Information

Andrea Zeke, MD; Amita Sudhir, MD

Peer Reviewed By

Ronna L. Campbell, MD, PhD; Jennifer Maccagnano, DO, FACEP, FACOEP

Publication Date

July 1, 2022

CME Expiration Date

July 1, 2025

CME Credits

4 AMA PRA Category 1 Credits™, 4 ACEP Category I Credits, 4 AAFP Prescribed Credits, 4 AOA Category 2-A or 2-B Credits.
Specialty CME Credits: Included as part of the 4 credits, this CME activity is eligible for 2 Pharmacology CME credits.

Pub Med ID: 35737570

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CME Information

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