Last reviewed: 27 Dec 2021
Last updated: 06 Jan 2022
08 Jul 2021

Updated UK guidance on the emergency treatment of anaphylaxis

The Resuscitation Council UK has released an update (May 2021) of its guidelines on the emergency treatment of anaphylaxis. New or revised recommendations include the following:

Corticosteroids (e.g., hydrocortisone) are no longer advised for routine emergency treatment of anaphylaxis.

  • Consider giving corticosteroids after initial resuscitation for refractory reactions or ongoing asthma or shock. Do not give corticosteroids preferentially to adrenaline.

Non-sedating oral antihistamines (e.g., cetirizine) are now recommended after stabilisation in preference to chlorphenamine, which causes sedation, especially in patients with persisting skin symptoms (urticaria and/or angioedema).

  • Antihistamines are considered a third-line treatment and should not be used to treat Airway/Breathing/Circulation problems during initial emergency management.

Intravenous fluids are recommended for refractory anaphylaxis, and must be given early if hypotension or shock is present.

Monitor for biphasic reactions as follows (this replaces guidance from NICE to monitor patients over 16 years old for 6-12 hours from onset of symptoms):

  • For at least 2 hours after resolution of symptoms (consider fast-track discharge) if:

    • A good response (within 5-10 minutes) to a single dose of adrenaline given within 30 minutes of onset of reaction, and

    • Complete resolution of symptoms, and

    • The patient has unused adrenaline and has been trained how to use them, and

    • There is adequate supervision following discharge

  • For at least 6 hours after resolution of symptoms if 2 doses of intramuscular adrenaline were given or there was a previous biphasic reaction.

  • For at least 12 hours following resolution of symptoms for patients with:

    • Severe reaction requiring >2 doses of adrenaline

    • Severe asthma or reaction involved severe respiratory compromise

    • The possibility of continuing absorption of the allergen (e.g., slow-release medicines)

    • Presentation late at night

    • Possible inability to respond to deterioration

    • Difficulty accessing emergency care.

See Management: approach

See Management: treatment algorithm

Original source of update



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
  • angio-oedema
  • 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
  • urea and electrolytes
  • arterial blood gases

Treatment algorithm


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




AA declares that he has no competing interests.

Thomas Palmer, BSc MBChB FRCEM

ST6 Emergency Medicine

Royal London Hospital




TP declares that he has no competing interests.


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



Michael Henning Andreae MD

Associate Professor

Department of Anesthesiology

Penn State Health Milton S. Hershey Medical Center




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




RT declares that he has no competing interests.


Celia Pincus,

Section Editor, BMJ Best Practice


CP declares that she has no competing interests.

Susan Mayor,

Lead Section Editor, BMJ Best Practice


SM works as a freelance medical journalist and editor, video editorial director and presenter, and communications trainer. In this capacity, she has been paid, and continues to be paid, by a wide range of organisations for providing these skills on a professional basis. These include: NHS organisations, including the National Institute for Health and Care Excellence, NHS Choices, NHS Kidney Care, and others; publishers and medical education companies, including the BMJ Group, the Lancet group, Medscape, and others; professional organisations, including the British Thoracic Oncology Group, the European Society for Medical Oncology, the National Confidential Enquiry into Patient Outcome and Death, and others; charities and patients’ organisations, including the Roy Castle Lung Cancer Foundation and others; pharmaceutical companies, including Bayer, Boehringer Ingelheim, Novartis, and others; and communications agencies, including Publicis, Red Healthcare and others. She has no stock options or shares in any pharmaceutical or healthcare companies; however, she invests in a personal pension, which may invest in these types of companies. She is managing director of Susan Mayor Limited, the company name under which she provides medical writing and communications services.

Rachel Wheeler,

Lead Section Editor, BMJ Best Practice


RW declares that she has no competing interests.

Julie Costello,

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

Adam Mitchell,

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

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