Summary
Definition
History and exam
Key diagnostic factors
- acute onset
- airway swelling (angio-oedema)
- inspiratory stridor and hoarse voice
- shortness of breath
- wheezing, chest hyperinflation, and accessory muscle use
- cyanosis
- respiratory arrest
- pale, clammy skin
- hypotension
- increased pulse rate (tachycardia)
- bradycardia
- cardiac arrest
- confusion or disorientation
- urticaria (hives)
- erythema
- pruritus
- rhinitis
- bilateral conjunctivitis
Other diagnostic factors
- risk factors
- nausea, vomiting, diarrhoea, and incontinence
- abdominal cramps and pain
- agitation, anxiety, and a sense of impending doom (angor animi)
Risk factors
- adult age: food-, insect venom- and medicine-related
- <30 years old: food-associated, exercise-induced
- female sex
- atopy/asthma
- history of anaphylaxis
- exposure to a common sensitiser (e.g., latex)
Diagnostic investigations
1st investigations to order
- mast cell tryptase
- 12-lead ECG
- blood gases
- urea and electrolytes
Investigations to consider
- chest x-ray
Treatment algorithm
presumed anaphylaxis: in cardiorespiratory arrest
presumed anaphylaxis: not in cardiorespiratory arrest
after initial treatment: not in cardiorespiratory arrest
post-anaphylaxis
Contributors
Expert advisers
Alexander Alexiou, MB BS BSc DCH FRCEM Dip IMC RCSEd
Emergency Medicine Consultant
Barts Health NHS Trust
Physician Response Unit Consultant
London’s Air Ambulance
Royal London Hospital
London
UK
Disclosures
AA declares that he has no competing interests.
Thomas Palmer, BSc MBChB FRCEM
Emergency Medicine Consultant
Royal London Hospital
London
UK
Disclosures
TP declares that he has no competing interests.
Acknowledgements
BMJ Best Practice would like to gratefully acknowledge the previous team of expert contributors, whose work has been retained in parts of the content:
Doerthe Adriana Andreae MD
Assistant Professor
Pediatric Allergy and Immunology
Penn State Health Milton S. Hershey Medical Center
Hershey
PA
Michael Henning Andreae MD
Associate Professor
Department of Anesthesiology
Penn State Health Milton S. Hershey Medical Center
Hershey
PA
Disclosures
DAA is author of an UpToDate article on food allergy and a number of references cited in this topic. MHA is an author of a reference cited in this topic.
Peer reviewers
Robert Taylor, MBChB MRCP(UK) MRCP(London) DipMedTox DipTher PGDME FHEA FRCEM
Acute Hospital Sub Dean (Cornwall)
Honorary Clinical Senior Lecturer
Consultant Emergency Physician
The Knowledge Spa
Royal Cornwall Hospital
Truro
UK
Disclosures
RT declares that he has no competing interests.
References
Key articles
Resuscitation Council (UK). Emergency treatment of anaphylactic reactions: guidelines for healthcare providers. May 2021 [internet publication].Full text
Cardona V, Ansotegui IJ, Ebisawa M, et al. World allergy organization anaphylaxis guidance 2020. World Allergy Organ J. 2020 Oct;13(10):100472.Full text Abstract
National Institute for Health and Care Excellence. Anaphylaxis: assessment and referral after emergency treatment. August 2020 [internet publication].Full text
Muraro A, Worm M, Alviani C, et al. EAACI guidelines: anaphylaxis (2021 update). Allergy. 2022 Feb;77(2):357-77.Full text Abstract
Reference articles
A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
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