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Allergy and anaphylaxis – Emergency

Allergy and anaphylaxis – Emergency management in children

Key points

  • Anaphylaxis is a rapidly evolving generalised multi-system allergic reaction to an allergen or trigger characterised by respiratory and/or cardiovascular features that can be fatal.
  • Anaphylaxis is under-recognised as symptoms may have resolved prior to ED presentation.
  • Adrenaline IM into the thigh is the first line treatment for anaphylaxis.
  • Caregivers of a child who has suffered anaphylaxis must receive two Adrenaline autoinjectors along with education on use and an individualised action plan on discharge from ED.
  • Adrenaline autoinjectors must be prescribed (and if possible dispensed) to all children who have suffered any allergic reaction (mild, moderate or severe) secondary to nut exposure as subsequent exposures may lead to more severe reactions (including anaphylaxis) and are less predictable compared to other foods.


This document provides clinical guidance for all staff involved in the care and management of a child presenting to an Emergency Department (ED) in Queensland with symptoms suggestive of an acute allergic reaction or anaphylaxis.

This guideline has been developed by senior ED clinicians and Paediatricians across Queensland, with input from Immunologists, Queensland Children’s Hospital, Brisbane. It has been endorsed for use statewide by the Queensland Emergency Care of Children Working Group in partnership with the Queensland Emergency Department Strategic Advisory Panel and the Healthcare Improvement Unit, Clinical Excellence Queensland.


An allergic reaction is an immunologically-mediated adverse reaction which occurs when a person’s immune system reacts to a substance (allergen) in the environment which would normally be innocuous. Allergens can enter the body via a number of different portals, including inhalation, ingestion, contact with skin and injection (parenteral medication or insect stings and bites).

Up to 40% of children in Australia and New Zealand are affected by allergic disorders at some time during their life, with 20% having current symptoms. Allergic diseases have approximately doubled in western countries over the last 25 years. The most common allergic conditions in children are food allergies, eczema, asthma and hayfever (allergic rhinitis).1

Most allergic reactions do not cause major problems, even though for many people they may be a source of extreme irritation and discomfort. A small number of people may experience a severe allergic reaction called anaphylaxis.

Anaphylaxis is an acute systemic allergic reaction in response to an allergen or trigger. It is caused by an IgE-mediated release of histamine, leukotrienes and prostaglandins from tissue mast cells and peripheral blood basophils.1,2 This reaction is multisystem in nature with systemic cardiovascular and/or respiratory symptoms and involvement of other systems such as the skin and gastrointestinal tract. Anaphylaxis may also be accompanied by signs of general allergic reaction.1,3 Urticaria / skin symptoms may be transient or subtle. Emergency departments tend to miss the diagnosis of anaphylaxis if the symptoms have resolved or if there is not a previous history of anaphylaxis.4

Non-immunologic anaphylaxis or ‘anaphylactoid’ reaction is an acute systemic reaction which is clinically identical to anaphylaxis. This occurs as a result of direct mast cell stimulation in response to a trigger and requires the same treatment.3,5

Food allergies are the most common cause of anaphylaxis in children. Common allergens include peanuts, tree nuts, wheat, sesame, egg, cow’s milk, fish, shellfish and on rare occasions spices, fruit and soy.5 Other causative agents include drugs, insects, latex, allergen therapy and, less commonly, exercise, cold and immunisations. In up to 30% of reactions, a cause cannot be identified.1

The prevalence of anaphylaxis in the paediatric population is estimated to be 1 in 1000.6 Admission rates for anaphylaxis are increasing in Australia with food allergies affecting 4 – 8% of children less than five years of age.1 Deaths from anaphylaxis are relatively rare but they are increasing in Australia with 324 deaths recorded between 1997 and 2013.7

Risk factors for fatal anaphylaxis include:1,8

  • asthma
  • delayed administration of adrenaline
  • age (teenagers and adults are at higher risk)
  • nut allergy


Emergency care should always involve a rapid primary survey with evaluation of (and immediate management of concerns with) airway, breathing, circulation and disability (ABCD). Consider pre-hospital treatment.


History taking should include specific information on allergic symptoms prior to hospital presentation with particular emphasis on cardiovascular or respiratory symptoms.

Once the patient is stabilised, the allergen trigger for the event should be identified (if possible).

Questioning should identify:

  • all foods and medications consumed several hours before the reaction
  • any possible stings or bites
  • current medications such as beta-blockers (as may affect response to treatment)
  • co-morbid diseases such as asthma (as can affect the severity of the reaction)


Clinical features of generalised allergic reaction and anaphylaxis
Generalised allergic reaction Anaphylaxis
Characterised by:

  • one or more of the following cutaneous features:
    • generalised pruritus
    • urticaria /angioedema
    • erythema


  • one or more of the following gastrointestinal features:
    • abdominal pain
    • vomiting
    • loose stools


  • no respiratory or cardiovascular signs or symptoms
Rapidly evolving generalised multi-system allergic reaction characterised by:

  • one or more of the following respiratory features:
    • difficulty / noisy breathing
    • swelling of tongue
    • swelling / tightness in throat
    • difficulty talking and/or hoarse voice
    • wheeze or persistent cough


  • one or more of the following cardiovascular features:
    • loss of consciousness
    • collapse
    • pallor and floppiness (in young children)
    • hypotension

May also involve other systems such as the skin or gastrointestinal tract.

Source: The Australian Society of Clinical Immunology and Allergy1

Anaphylaxis requires ONLY ONE respiratory or cardiovascular component to make a diagnosis.

Differential diagnoses

Differential diagnoses for symptoms of anaphylaxis
Clinical presentation Differential diagnoses
Swelling of lips and tongue Idiopathic or hereditary angioedema
Cardio-vascular compromise including hypotension All forms of shock
Stridor, drooling or respiratory distress Upper airway obstruction causes including foreign body, epiglottitis, and croup
Flushing of the face, headache, heart palpitations, itching, blurred vision, cramps and diarrhoea within minutes to an hour of consuming contaminated fish Scombroid poisoning (histamine poisoning from fish) – easily confused as seafood is a common cause of anaphylaxis


Investigations are not routinely recommended. Histamine levels fall too rapidly to be clinically useful.  Occasionally tryptase levels collected within three hours of symptom onset may be useful but should only be collected on advice from Immunologist/Allergist.

The use of other laboratory and radiological tests should be guided by patient co-morbidities and circumstances, including incidental trauma.9


Refer to flowchart for a summary of the emergency management of children with an acute allergic reaction.

  • ALERT – Some insect bites or stings can result in severe abdominal pain and vomiting. This represents a severe allergic reaction and should be managed as for anaphylaxis.

Anaphylaxis is often under-diagnosed due to the variable nature and duration of symptoms.

Given the potential for rapid deterioration administer Adrenaline IM immediately into the thigh if anaphylaxis is suspected.


Initial management includes rapid triage and clinical assessment of the patient’s airway patency, breathing (ventilation and oxygenation) and circulation. Intervention and stabilisation should occur immediately. Continuous cardiac and oxygen saturation monitoring is recommended. Children with less severe generalised allergic symptoms may initially appear stable but have the potential for rapid deterioration.9


  • Adrenaline IM into the thigh is the recommended first-line treatment of anaphylaxis
  • effective for all the symptoms and signs of anaphylaxis2
  • associated with a decreased fatality rate if administered promptly10

Studies have demonstrated that peak plasma levels are achieved significantly faster after IM injection into the thigh compared with SC injection into the arm.11,12

Nebulised Adrenaline may help relieve upper airway obstruction and/or bronchospasm but should only be administered in addition to Adrenaline IM.

  • ALERT – Adrenaline IV should be reserved for the following children:
    • immediately life-threatening profound shock
    • circulatory compromise and continuing to deteriorate after Adrenaline IM
    • ongoing rebound of anaphylaxis despite recurrent Adrenaline IM

Where Adrenaline IV is indicated, a continuous low dose Adrenaline infusion is the safest and most effective form of administration.13 Significant adverse events including fatal cardiac arrhythmia and cardiac infarction have been reported when Adrenaline IV is administered too rapidly, inadequately diluted or in excessive dose.14 An Adrenaline IV bolus is not recommended.

Adrenaline dosing for the treatment of anaphylaxis in children
Adrenaline (IM) 10 microgram/kg (maximum 0.5 mg)
~ 0.01 mL/kg of 1:1000 solution (undiluted)
Repeat as necessary every five minutes
Adrenaline (NEB) 5 mL of undiluted 1:1000 Adrenaline nebulised with oxygen
Adrenaline (IV infusion) With Smart Pump Drug Errors Reducing System:
1 mL of 1:1000 Adrenaline solution (contains 1 mg) in 50 mL of Sodium Chloride 0.9%
Start infusion at 0.1 microgram/kg/min
Without Smart Pump Drug Errors Reducing System:
1 mL of 1:1000 Adrenaline solution in (contains 1 mg) in 50 mL of Sodium Chloride 0.9%
Start infusion at 0.3 mL/kg/hour (0.1 microgram/kg/min)
  • Seek urgent paediatric critical care advice (onsite or via Retrieval Services Queensland (RSQ)) for a child requiring more than two doses of Adrenaline IM or prior to administering Adrenaline IV.


Children suffering from anaphylaxis who have respiratory distress without circulatory instability should be initially nursed in a sitting up position.

While the vast majority of children respond well to Adrenaline IM, airway swelling can occur rapidly. Preparation for early intubation including a range of ETT sizes (with several sizes smaller than usual) is recommended. In anaphylaxis, the airway should always be considered potentially “difficult” and caution should be exercised when opting for heavy sedation or long-acting paralytic agents.9 Laryngeal mask airway (LMA) may not be effective due to oropharyngeal angioedema and bronchospasm.

  • Seek senior emergency/paediatric advice as per local practices for a child with airway concerns following administration of Adrenaline IM.
  • Contact the most senior resources available onsite (critical care/anaesthetic/ENT) prior to intubating a child with anaphylaxis.


  • high flow supplemental oxygen via non-rebreather mask is recommended


  • children with circulatory compromise should be nursed lying down
  • elevate the lower extremities to conserve circulating volume
  • IV access with two large-bore (age-appropriate) cannula, or intraosseous access, is recommended for children with severe symptoms at risk of circulatory compromise
Fluid resuscitation for the management of shocked children
Bolus dose
(IV or IO)
Sodium Chloride 0.9% administered rapidly in 20 mL/kg bolus.
Repeat in 20 mL/kg boluses as clinically indicated.
  • Seek urgent paediatric critical care advice (onsite or via RSQ) for a child in shock who is not responding to Adrenaline and fluids.

Inhaled bronchodilators

  • may help relieve bronchospasm if lower airway obstruction (wheeze) is a concern18
  • should only be used as an adjunct to first-line treatment for anaphylaxis


While corticosteroids are commonly recommended as second-line treatment internationally, little evidence supports their use in anaphylaxis. No randomised controlled trials (in adults or children) were identified in a Cochrane Systematic Review of glucocorticoids for the treatment of anaphylaxis.15 The primary action of glucocorticoids is down-regulation of the late-phase eosinophilic inflammatory response, as opposed to the early-phase response. Short-term glucocorticoid treatment is seldom associated with adverse effects.16 The proposed rationale for corticosteroid administration is to prevent biphasic or protracted reactions.2 However, in two paediatric studies of biphasic reactions the administration of steroids did not appear to be preventative.2 Steroids are not recommended unless there is a component of asthma aggravation with the anaphylaxis which should be treated concurrently as per the Asthma Guideline.


  • not recommended in acute anaphylaxis as there is no evidence to support use17

Generalised and local allergic reaction


  • H1 antagonists are recommended to treat allergy symptoms including urticaria, angioedema and itchiness
  • two-to-four-day-course taken orally is recommended to alleviate persistent symptoms after a severe allergic reaction
  • ALERT – Sedating antihistamines including promethazine (Phenergan) or dexchlorpheniramine maleate (Polaramine) are NOT recommended as may cause significant side effects such as respiratory depression, especially in younger children.
Antihistamine dosing for the treatment of allergic reaction in children
Antihistamine Age Dose
Cetirizine (Oral)
1-2 years 2.5 mg twice daily
2-6 years 5 mg once daily or 2.5 mg twice daily
6-12 years 10 mg once daily or 5 mg twice daily
12-18 years 10 mg once daily

*Loratadine, Fexofenadine and Desloratadine are not available within QH Hospitals but are available in the community. Fexofenadine and Desloratadine can be prescribed to infants 6 months and over.

Escalation and advice outside of ED

  • Critically unwell or rapidly deteriorating child

Includes children with the following (as a guide)
• ongoing airway, breathing or circulation involvement
• requiring more than two doses of Adrenaline IM
• requiring Adrenaline IV
• in shock
• physiological triggers based on age (see below)

Less than 1 year 1-4 years 5-11 years Over 12 years
• RR >50
• HR <90 or >170
• sBP <65
• SpO2 <93% in oxygen or <85% in air
• GCS ≤12
• RR >40
• HR <80 or >160
• sBP <70
• SpO2 <93% in oxygen or <85% in air
• GCS ≤12
• RR >40
• HR <70 or >150
• sBP <75
• SpO2 <93% in oxygen or <85% in air
• GCS ≤12
• RR >30
• HR <50 or >130
• sBP <85
• SpO2 <93% in oxygen or <85% in air
• GCS ≤12
Reason for contact Who to contact
For immediate onsite assistance including airway management
(anticipate difficult airway)
The most senior resources available onsite at the time as per local practices.
Options may include:

  • paediatric critical care
  • critical care
  • ENT
  • anaesthetics
  • paediatrics
  • Senior Medical Officer (or similar)
Paediatric critical care advice and assistance Onsite or via Retrieval Services Queensland (RSQ).
If no onsite paediatric critical care service contact RSQ on 1300 799 127:

  • for access to paediatric critical care telephone advice
  • to coordinate the retrieval of a critically unwell child

RSQ (access via QH intranet)
Notify early of child potentially requiring transfer.
Consider early involvement of local paediatric/critical care service.
In the event of retrieval, inform your local paediatric service.

  • Non-critical child

May include children with:
  • generalised allergic reaction
  • anaphylaxis
Reason for contact Who to contact
(including management, disposition or
Follow local practices. Options:

  • onsite/local paediatric service
  • Queensland Children’s Hospital experts via Children’s Advice and Transport Coordination Hub (CATCH) on 13 CATCH (13 22 82)
    (24-hour service)
  • local and regional paediatric videoconference support via Telehealth Emergency Management Support Unit TEMSU (access via QH intranet) on 1800 11 44 14 (24-hour service)
Referral First point of call is the onsite/local paediatric service

Inter-hospital transfers

Do I need a critical transfer?
Request a non-critical inter-hospital transfer
Non-critical transfer forms


When to consider discharge from ED

Children with a localised or general allergic reaction

Children with a localised allergic reaction may be safely discharged.

Children with a general allergic reaction may be safely discharged provided symptoms have not progressed and are improving within one hour of observation.

On discharge

  • parents / carers should be educated on allergic reactions and instructed to return immediately if symptoms recur
  • Adrenaline autoinjectors must be prescribed (and if possible dispensed) to all children who have suffered any allergic reaction (mild, moderate or severe) secondary to nut exposure as subsequent exposures may lead to more severe reactions (including anaphylaxis) and are less predictable compared to other foods


  • with GP within a week.

For children with a generalised allergic reaction, consider referral to a local Immunologist (via ED or GP) on discharge. Refer to the ASCIA website ( ) for registered local Immunologists. Refer to local Paediatrician if no local Immunology service.

Children with anaphylaxis

Consider discharge for children who meet the following criteria:

  • resolution of respiratory and CVS symptoms
  • an observation period of four hours following administration of Adrenaline IM.

Prior to discharge, consider other factors including the time of day, parents/carers comprehension and compliance, access to transport should return be required and distance to the local hospital.

On discharge

  • caregivers must receive:
    • two Adrenaline autoinjectors (AAI) or ampoules according to weight (see table below)
    • education on how and when to administer the AAI or Adrenaline ampoules (refer to ASCIA website website)
    • an individualised Action Plan (see Action Plan for Anaphylaxis on ASCIA website)
    • general information regarding allergies and anaphylaxis management (see ASCIA website)
  • the child and their caregiver/s should be encouraged to document the circumstances leading up to an episode of anaphylaxis (up to six to eight hours prior to symptoms)
Weight of child Adrenaline recommended on discharge
Less than 8.5 kg Adrenaline ampoules 1:1000
8.5-20 kg Epipen Jr autoinjector
Greater than 20 kg Epipen autoinjector


  • refer (via ED or GP) to Immunologist/Allergy specialist if available locally, otherwise refer to local Paediatrician
  • if allergen known to be food related, consider referral to local dietician

When to consider admission

Facilities without a Short Stay Unit (SSU)

Admission is recommended for children with anaphylaxis who:

  • have persistent symptoms four hours after treatment
  • required more than two Adrenaline doses (due to possibility of recurrent symptoms)

Facilities with a Short Stay Unit (SSU)

Consider admission to a SSU for children who are responding to treatment but require a period of observation prior to meeting the criteria for discharge.

When to consider admission to inpatient ward from SSU
Admission to an inpatient service is recommended for children who require more than two Adrenaline doses (due to possibility of recurrent symptoms) or who are failing to improve after 12 hours of care.


  1. Australian Society of Clinical Immunology and Allergy (ASCIA). (2009), ASCIA Guidelines for adrenaline autoinjector prescription,] online] Available at: [cited 2011 July 21].
  2. Santillanes, G., Davidson, J. (2010), ‘An evidence-based review of pediatric anaphylaxis’, Pediatric Emergency Medicine Practice, 7(10).
  3. de Silva, I.L., Mehr, S.S., Tey, D., et al. (2008), ‘Paediatric anaphylaxis: a 5-year retrospective review‘, Allergy. 63 (8): pp. 1071-1076.
  4. Thomson, H., Seith R., Craig, S. (2017) ‘Inaccurate diagnosis of paediatric anaphylaxis in three Australian Emergency Departments’, Journal of Paediatrics and Child Health, 53: pp 698-704.
  5. Queensland Health, Department of Emergency Medicine: Royal Children’s Hospital (Brisbane). (2008), Department of emergency medicine clinical guidelines, 7th Queensland Government: Brisbane (AU): p. 24
  6. Branganza, S.C., Acworth, J.P., Mckinnon, D.R., et al. (2006), ‘Paediatric emergency department anaphylaxis: Different patterns from adults’, Archives of Disease in Childhood, 91 (2): pp. 159-163.
  7. Mullins, R.J., Wainstein, B.K., Barnes, E.H., Liew, W.K., Campbell, D.E. (2016), ‘Increase in anaphylaxis fatalities in Australia from 1997 to 2013’, Clinical & Experimental Allergy, 46: pp. 1099-1110.
  8. Pumphrey, R. (2004), ‘Anaphylaxis: Can we tell who is at risk of a fatal reaction?’, Current Opinion in Allergy and Clinical Immunology. 4 (4): pp. 285-290.
  9. Davis, J. (2005), ‘Allergies and anaphylaxis: analysing the spectrum of clinical manifestations’, Emergency Medicine Practice, 7(10): pp. 1-23.
  10. Sheikh, A., Shehata, Y.A., Brown, S.G.A., et al. (2008), ‘Adrenaline (epinephrine) for the treatment of anaphylaxis with and without shock’, Cochrane Database of Systematic Reviews, Issue 4. Art. No.: CD006312.
  11. Simons, F.E.R., Roberts, J.R., Gu, X., et al. (1998), ‘Epinephrine absorption in children with a history of anaphylaxis’, Journal of Allergy and Clinical Immunology, 101 (1): pp. 33-37.
  12. Simons, F.E.R., Gu, X., Simons, K.J. (2001), ‘Epinephrine absorption in adults: Intramuscular versus subcutaneous injection’, Journal of Allergy and Clinical Immunology, 108 (5): pp. 871-873.
  13. Davis, J.E., Norris, R.L. (2007), ‘Allergic emergencies in children: The pivotal role of epinephrine’, Pediatric Emergency Medicine Practice, 4 (2).
  14. McLean-Tooke, A.P.C., Bethune, C.A., Fay, A.C., et al. (2003), ‘Adrenaline in the treatment of anaphylaxis: What is the evidence?’, British Medical Journal, 327 (7427): pp. 1332-1335.
  15. Choo, K.J.L., Simons, F.E.R., Sheikh, A. (2010), ‘Glucosteroids for the treatment of anaphylaxis (review)’, Cochrane Database of Systematic Reviews., Issue 3. Art. No.: CD007596.
  16. Schleimer, R.P. (2008), ‘Pharmacology of glucocorticoids in allergic disease’, in Middleton’s Allergy Principles and Practice, eds N.F. Adkinson, B.S. Bochnet, W.W. Busse, et al., 7th edn, Mosby:St Louis, pp. 1549-1574.
  17. Sheikh, A., ten Broek, V.M., Brown, S.G.A., et al. (2007), ‘H1-antihistamines for the treatment of anaphylaxis with and without shock’, Cochrane Database of Systematic Reviews, Issue 1. Art. No.: CD006160.

Guideline approval

Guideline approval history
Document ID CHQ-GDL-60011 Version no. 4.0 Approval date 26/02/2021
Executive sponsor Executive Director Medical Services Effective date 26/02/2021
Author/custodian Queensland Emergency Care Children Working Group Review date 26/02/2024
Supersedes 3.0
Applicable to Queensland Health medical and nursing staff
Document source Internal (QHEPS) + External
Authorisation Executive Director Clinical Services QCH
Keywords Allergy, anaphylaxis, acute allergic reaction, Paediatric, emergency, guideline, children, 60011
Accreditation references NSQHS Standards (1-8): 1 Clinical Governance, 4 Medication Safety, 8 Recognising and Responding to Acute Deterioration


This guideline is intended as a guide and provided for information purposes only. View full disclaimer.
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