Anaphylaxis | Acute Management | ABCDE

Anaphylaxis is a life-threatening condition that you need to be able to recognise and manage in an acute setting. This guide gives an overview of the recognition and immediate management of anaphylaxis (using an ABCDE approach). You can check out our overview of the ABCDE approach here.

This guide has been created to assist students in preparing for emergency simulation sessions as part of their training, it is not intended to be relied upon for patient care.

Clinical features of anaphylaxis

Anaphylaxis can present in a wide variety of ways, making early diagnosis sometimes difficult.

The resuscitation council (UK) have devised the following set of criteria that if met suggest anaphylaxis is likely:

  • Sudden onset and rapid progression of symptoms (most reactions occur over several minutes)
  • Life-threatening Airway and/or Breathing and/or Circulation problems
  • Skin and/or mucosal changes (flushing, urticaria, angioedema)

The exposure to a known allergen also helps support the diagnosis of anaphylaxis.


Other key points:

  • Skin or mucosal changes alone are not a sign of an anaphylactic reaction
  • Skin and mucosal changes can be subtle or absent in up to 20% of reactions
  • There can also be gastrointestinal symptoms (e.g. vomiting, abdominal pain, incontinence)

Tips before you begin

  • Treat all problems as you find them
  • Re-assess regularly and after every intervention to see if your management is effective
  • Make use of the team around you to delegate tasks where appropriate – is another clinical member of staff available to help you?
  • All critically unwell patients should have continuous monitoring equipment attached for accurate observations, blood pressure and if necessary ECG readings – this will save you time!
  • Communicate how often would you like these readings to be relayed to you
  • If you need senior input for your patient, call for help early using an appropriate SBARR handover structure (check out the guide here)
  • Review results e.g. laboratory investigations as they become available
  • Make use of medical school/hospital guidelines and algorithms in managing specific situations such as anaphylaxis
  • Any medications or fluids will need to be prescribed
  • Your assessment and management should be documented in the notes

Initial steps

You are likely to see this patient after a brief handover from another member of staff.


Introduce yourself to whoever has requested a review of the patient.



Perform a quick general inspection of the patient to get a sense of how unwell they are:

  • Check consciousness level using AVPU
  • How do they look?
  • How is their breathing?
  • Are there obvious skin/mucosal changes?
  • What is around the bedside? (look for IV lines, monitoring equipment etc).



  • Introduce yourself to the patient
  • Ask the patient how they are feeling – patients’ with anaphylaxis often experience an initial sense of anxiety that progresses rapidly to them feeling and looking very unwell



  • Make sure the patient’s notes, observation chart and prescription chart are on hand
  • Ask for another clinical member of staff to assist you if possible

If the patient is unconscious or unresponsive, start the basic life support (BLS) algorithm as per resuscitation guidelines.


If anaphylaxis is suspected, the immediate removal of potential anaphylactoid triggers such as IV antibiotics should be performed. In addition, you should ask another member of staff to source adrenaline (1:1000) to allow this to be administered quickly once you have confirmed the diagnosis.



Assess the patient’s ability to speak, listen to the patient’s breathing for added sounds and inspect the mouth:

  • Airway swelling may be present (pharyngeal/laryngeal oedema) causing the patient to have difficulty speaking (hoarse voice), breathing, and swallowing (the patient may complain of feeling like their airway is closing up)
  • Stridor (a high pitched inspiratory noise) indicates upper airway obstruction
  • Angioedema (tongue and lip swelling) may be present



If any of the above features are present you should immediately put out a crash call as you require urgent anaesthetic input to secure the airway. In the meantime, you can perform some basic airway manoeuvres to help maintain the airway.

Maintaining the airway whilst awaiting senior input

1. Perform head tilt, chin lift manoeuvre 

2. If noisy breathing persists try a jaw thrust

3. If airway still appears compromised use an airway adjunct:

  • Insert an oropharyngeal airway (Guedel) only if unconscious (as otherwise may gag/aspirate)
  • Alternatively, use a nasopharyngeal airway (better tolerated if the patient is partially conscious)

Re-assess after any intervention.




Respiratory rate:

  • Tachypnoea is concerning and suggestive of significant respiratory compromise.
  • A falling or normal respiratory rate in the context of hypoxia is a sign of impending respiratory arrest and need for urgent critical care review.

Oxygen saturation monitoring – aim for 94-98%



Auscultate both lungs:

  • Assess air entry – reduced air entry suggests significant airway compromise and need for critical care input
  • Note any wheezing – wheeze becomes less apparent with increasing airway obstruction

Cyanosis may be present in severe cases and is a late sign.



Arterial blood gas

An arterial blood gas may be useful in quantifying the degree of hypoxia, however, it should not delay emergency management of anaphylaxis.


Chest x-ray

A portable chest x-ray may be useful in ruling out other respiratory diagnoses if shortness of breath is the primary issue (e.g. pneumothorax/pneumonia/pulmonary oedema).  Chest x-ray should not delay emergency management of anaphylaxis and should only be performed if the diagnosis is in doubt.



Administer oxygen

Sit the patient upright if hypoxia is the primary issue, however, if the patient is hypotensive this can result in loss of consciousness and therefore may need to be avoided.

Give high-flow oxygen (15 litres) via a non-rebreathe mask.

In practice, high flow oxygen should be administered as soon as it is available whilst you continue your assessment.

Maintain oxygen saturations between 94–98%.


Administer nebulised bronchodilators

Give nebulised bronchodilators if there is suspicion of bronchospasm (e.g. wheezing):

  • Salbutamol – doses vary – in severe cases, continuous nebulisation is advised
  • Ipratropium bromide – 500mcg nebulised

Re-assess after any intervention.





  • Tachycardia is common due to hypovolaemic shock
  • Bradycardia is a late sign, often preceding cardiac arrest


Blood pressure:

  • Haemodynamic shock occurs secondary to fluid compartment shifts resulting in significant hypotension
  • The patient may complain of feeling faint or lose consciousness if hypotension is severe



Inspection – patient may be pale/clammy


  • Peripherally cool due to hypotension
  • Pulse – weak/thready due to hypotension
  • Prolonged capillary refill time (normally <2 seconds)



Take blood samples (ideally during cannulation) – FBC / U&E / LFT / Clotting / CRP / Mast cell tryptase

Record an ECG – this should not delay any other treatment however an ECG should be performed at some point as anaphylaxis can cause myocardial ischaemia (even in patients with normal coronary arteries). ²



Administer intramuscular (IM) adrenaline

Administer IM adrenaline (1:1000) immediately: ²

  • Adult dose – 0.50 mL of 1:1000 adrenaline
  • Repeat administration every 5 minutes if patient remains in haemodynamic shock (max 5mL)
  • The recommended site for injection is the anterolateral aspect of the middle third of the thigh
  • If the patient remains shocked after 2 doses then an adrenaline infusion may be needed (this will be a consultant/critical care led decision).


Administer intravenous (IV) fluids and medication

Gain IV access – large bore cannulas required for rapid fluid resuscitation

Intravenous fluids (STAT)  – NaCl 0.9% / Hartmann’s solution – titrate to fluids depending on haemodynamic stability – large volumes may be required (an initial bolus of 500-1000mls is recommended) 2

Chlorphenamine – 10mg IV (adult) – stabilises mast cells – reducing histamine release ¹ (give after fluid resuscitation – DO NOT delay fluid resuscitation)

Hydrocortisone – 200mg IV (adult) – prevents rebound of inflammation over next few hours ¹ (give after fluid resuscitation – DO NOT delay fluid resuscitation)


If the patient remains hypotensive, they will need admission to critical care for inotropic support.

If the patient has a cardiac arrest, commence CPR as per advanced life support guidelines.

Re-assess after any intervention.


Assess level of consciousness – AVPU/GCS:

  • The above Airway, Breathing and Circulation problems can all alter the patient’s neurological status because of decreased cerebral perfusion, causing the patient to be confused and agitated.
  • Loss of consciousness can occur due to hypotension and severe hypoxia.

A falling level of consciousnesses is a sign of serious deterioration and will require critical care input for further support (e.g. intubation).

Re-assess after any intervention.


Allergens – identify and remove any potential anaphylactoid triggers

Expose the patient’s body looking for any skin or mucosal changes (often the first feature present in anaphylaxis):

  • Erythema – patchy or generalised red rash
  • Urticaria:
    • Can appear anywhere on the body (weals may be pale, pink or red and may look like nettle stings)
    • They can be different shapes/sizes and are often surrounded by a red flare
    • They are usually itchy
  • Angioedema:
    • Similar to urticaria but involves the swelling of deeper tissues
    • Most commonly the areas affected include the eyelids, lips, mouth and throat

Re-assess after any intervention.

Reassess ABCDE

It is essential to continually reassess ABCDE and treat issues as you encounter them.  This allows continual reassessment of the response to treatment and early recognition of deterioration.

If anaphylaxis is suspected then critical care should be contacted immediately as their support will be needed.

Next steps

Well done! You’ve stabilised the patient and they’re doing much better. Just a few more things to do…

Take a history

Take a more detailed history of what has happened and how the patient has been. Involve staff or family members as appropriate.
Check out our history taking guides here


Review the patient’s notes, observations, fluid charts, and any investigation findings. Double check the medications you have just prescribed, and any routine medications the patient is taking.


Document your ABCDE assessment clearly, including examination, observations, investigations, interventions, and patient response/changing condition. Write down any pertinent details from your history-taking. If you suspect a particular substance caused the anaphylactic reaction this should be documented clearly in the patient’s allergy status on all drug charts and in the notes.

See documentation guide



If a senior doctor hasn’t already been involved, it is important to contact them and make them aware of the unwell patient. As a junior doctor, it would be appropriate to give an SBARR handover outlining your assessment and actions, and to discuss the following:

  • Are any further assessments or interventions required?
  • Does the patient need a referral to HDU/ICU?
  • Should they be referred for a review by a speciality doctor?
  • Should any changes be implemented to the management of any underlying conditions?


The next team of doctors on shift should be made aware of any patient in their department who has become acutely unwell.


1. Australian Prescriber – Emergency management of Anaphylaxis – [LINK]
2. Resuscitation Council (UK) – Emergency treatment of anaphylactic reactions – [LINK]

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