Anaphylaxis

Overview

Anaphylaxis is the most severe clinical presentation of acute systemic allergic reactions. It is a life-threatening generalized or systemic allergic or hypersensitivity reaction that is rapid in onset and may cause death. The occurrence of anaphylaxis has increased in recent years, and every healthcare professional is expected to recognize and manage it.^[1][31]

The diagnosis is clinical, made by recognizing a constellation of presenting features — not by any single test or threshold. All four major international guideline groups (WAO, EAACI, NICE and national resuscitation councils) concur on the core features that indicate a likely diagnosis and on prompt intramuscular adrenaline as initial treatment.^[3][4]

Two failures dominate real-world care. First, adrenaline is given late, or not at all, while antihistamines and corticosteroids are given instead. Second, patients leave without auto-injectors, without training and without specialist referral. Both failures are correctable in general practice, and both are the difference between a survived and a fatal recurrence.^[1][13]

References36ShowHide

1. [1]Cardona V, Ansotegui IJ, Ebisawa M et al. World allergy organization anaphylaxis guidance 2020. The World Allergy Organization journal, 2020.PMID 33204386
2. [2]Muraro A, Worm M, Alviani C et al. EAACI guidelines: Anaphylaxis (2021 update). Allergy, 2022.PMID 34343358
3. [3]Muraro A, Roberts G, Worm M et al. Anaphylaxis: guidelines from the European Academy of Allergy and Clinical Immunology. Allergy, 2014.PMID 24909803
4. [4]Simons FE, Ardusso LR, Bilò MB et al. International consensus on (ICON) anaphylaxis. The World Allergy Organization journal, 2014.PMID 24920969
5. [5]Campbell RL, Bellolio MF, Knutson BD et al. Epinephrine in anaphylaxis: higher risk of cardiovascular complications and overdose after administration of intravenous bolus epinephrine compared with intramuscular epinephrine. The journal of allergy and clinical immunology. In practice, 2015.PMID 25577622
6. [6]Lee S, Bellolio MF, Hess EP et al. Time of Onset and Predictors of Biphasic Anaphylactic Reactions: A Systematic Review and Meta-analysis. The journal of allergy and clinical immunology. In practice, 2015.PMID 25680923
7. [7]Lee S, Bellolio MF, Hess EP et al. Predictors of biphasic reactions in the emergency department for patients with anaphylaxis. The journal of allergy and clinical immunology. In practice, 2014.PMID 24811018
8. [8]Simard D, Bouchard V, Plourde A et al. Factors influencing emergency department observation time following anaphylaxis: a systematic review. CJEM, 2021.PMID 33844191
9. [9]Schroter S, Laubach S, Bialostozky M et al. Reducing Emergency Department Observation Time for Patients with Low-Risk Anaphylaxis. Pediatrics, 2026.PMID 42556817
10. [10]Koken G, Ertoy Karagol HI, Polat Terece S et al. Biphasic, Refractory, and Persistent Anaphylaxis in Children. Clinical and translational allergy, 2026.PMID 42086893
11. [11]Choo KJ, Simons FE, Sheikh A Glucocorticoids for the treatment of anaphylaxis. Evidence-based child health : a Cochrane review journal, 2013.PMID 23877942
12. [12]Sheikh A Glucocorticosteroids for the treatment and prevention of anaphylaxis. Current opinion in allergy and clinical immunology, 2013.PMID 23507835
13. [13]Delli Colli L, Al Ali A, Gabrielli S et al. Managing anaphylaxis: Epinephrine, antihistamines, and corticosteroids: More than 10 years of Cross-Canada Anaphylaxis REgistry data. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 2023.PMID 37689113
14. [14]Mateja A, Wang Q, Chovanec J et al. Defining baseline variability of serum tryptase levels improves accuracy in identifying anaphylaxis. The Journal of allergy and clinical immunology, 2022.PMID 34425177
15. [15]Vitte J, Sabato V, Tacquard C et al. Use and Interpretation of Acute and Baseline Tryptase in Perioperative Hypersensitivity and Anaphylaxis. The journal of allergy and clinical immunology. In practice, 2021.PMID 33746087
16. [16]Gonzalez C, Sun M, Morand A et al. Pediatric anaphylaxis in the emergency department: Performances of dynamic tryptase measurement. The journal of allergy and clinical immunology. Global, 2025.PMID 40697951
17. [17]Srivastava S, Huissoon AP, Barrett V et al. Systemic reactions and anaphylaxis with an acute serum tryptase ≥14 μg/L: retrospective characterisation of aetiology, severity and adherence to National Institute of Health and Care Excellence (NICE) guidelines for serial tryptase measurements and specialist referral. Journal of clinical pathology, 2014.PMID 24782357
18. [18]Tanno LK, Luong PTV, Dieval M et al. Anaphylaxis and pregnancy: Epidemiology, elicitors, and recurrences. The World Allergy Organization journal, 2025.PMID 41488546
19. [19]McKenzie BA, Marshall SD, Sanci LA et al. Mechanism of Cardiac Arrest in Fatal Anaphylaxis. Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology, 2026.PMID 41876126
20. [20]Yamaguchi M, Fukutomi Y, Kondo Y et al. Is intramuscular adrenaline used promptly against drug-induced anaphylaxis? A perspective from recent analyses of fatal cases in Japan. Allergology international : official journal of the Japanese Society of Allergology, 2026.PMID 41792003
21. [21]Khalaf R, Saleem R, Prosty C et al. Clinical Presentation, Triggers, Comorbidities, and Management of Anaphylaxis in the Elderly: A Cross-Sectional Study. International archives of allergy and immunology, 2026.PMID 40924635
22. [22]Keser-Ozturk N, Maghdeed Y, Bozkurt S et al. Triggers, clinical spectra and outcomes of pediatric anaphylaxis in a tertiary center: impact of comorbidities and cofactors on severity. Allergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology, 2026.PMID 42321881
23. [23]Vale S, Smith J, Said M et al. ASCIA guidelines for prevention of anaphylaxis in schools, pre-schools and childcare: 2015 update. Journal of paediatrics and child health, 2015.PMID 26428419
24. [24]Patel N, Isaacs E, Duca B et al. Optimal dose of adrenaline auto-injector for children and young people at risk of anaphylaxis: A phase IV randomized controlled crossover study. Allergy, 2023.PMID 36794963
25. [25]Hlady AL, Weinman AF, Zhang Y et al. Outcomes associated with prehospital epinephrine in adult and pediatric patients with anaphylaxis. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 2024.PMID 39154908
26. [26]Lieberman P, Simons FE Anaphylaxis and cardiovascular disease: therapeutic dilemmas. Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology, 2015.PMID 25711241
27. [27]McLure M, Eastwood K, Parr M et al. A rapid review of advanced life support guidelines for cardiac arrest associated with anaphylaxis. Resuscitation, 2021.PMID 33068641
28. [28]Krishnaswamy G Critical Care Management of the Patient With Anaphylaxis: A Concise Definitive Review. Critical care medicine, 2021.PMID 33653974
29. [29]Galvan-Blasco P, Pereira-Gonzalez J, Cardona V Update on refractory anaphylaxis. Current opinion in allergy and clinical immunology, 2025.PMID 40747971
30. [30]Golden DBK, Wang J, Waserman S et al. Anaphylaxis: A 2023 practice parameter update. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 2024.PMID 38108678
31. [31]Sicherer SH, Simons FER Epinephrine for First-aid Management of Anaphylaxis. Pediatrics, 2017.PMID 28193791
32. [32]Worm M, Nguyen D, Rackley R et al. Epinephrine delivery via EpiPen(®) Auto-Injector or manual syringe across participants with a wide range of skin-to-muscle distances. Clinical and translational allergy, 2020.PMID 32528643
33. [33]Kadivec S, Košnik M The Ability to Use Epinephrine Autoinjector in Patients Who Receive Prescription Immediately after Anaphylaxis. International archives of allergy and immunology, 2021.PMID 33486490
34. [34]Narchi H, Elghoudi A, Al Dhaheri K Barriers and challenges affecting parents' use of adrenaline auto-injector in children with anaphylaxis. World journal of clinical pediatrics, 2022.PMID 35433301
35. [35]Michaelis LJ, Owen T, Bright AD et al. Adrenaline Auto-Injector Prescribing in Primary Care in England: An Analysis of Non-Standard Dosing. Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology, 2026.PMID 41178123
36. [36]Dzingina M, Stegenga H, Heath M et al. Assessment and referral after emergency treatment of a suspected anaphylactic episode: summary of NICE guidance. BMJ, 2011.PMID 22171344