Anaphylaxis or allergic reactions

Any person, 16 years and over, presenting with acute onset of a generalised reaction or a multisystem allergic reaction, characterised by cardiovascular or respiratory symptoms usually associated with typical skin features and/or gastrointestinal symptoms.

History prompts, signs and symptoms

These are not exhaustive lists. Maintain an open mind and be aware of cognitive bias.

Red flags

Recognise: identify indicators of actual or potential clinical severity and risk of deterioration.

Respond: carefully consider alternative ECAT protocol. Escalate as per clinical reasoning and local CERS protocol, and continue treatment.

Clinical assessment and specified intervention (A to G)

If the patient has any Yellow or Red Zone observations or additional criteria (as per the relevant NSW Standard Emergency Observation Chart), refer and escalate as per local CERS protocol and continue treatment.

Position

Assessment	Intervention
General appearance/first impressions	Do not allow patient to sit up suddenly, stand, or walk Allow patient to adopt a safe position of comfort as tolerated If hypotensive, elevate feet

Airway

Assessment	Intervention
Patency of airway Signs of airway compromise Stridor Hoarseness Difficulty talking Changes in voice or cry Tongue or facial swelling	Maintain airway patency Consider airway opening manoeuvres and positioning

Breathing

Assessment	Intervention
Respiratory rate and effort Auscultate chest (breath sounds) Oxygen saturation (SpO2)	Assist ventilation, as clinically indicated Apply oxygen Apply continuous cardiorespiratory monitoring To assist with breathing difficulties, keep patient supine at 45° – do not sit upright suddenly

Circulation

Assessment	Intervention
Perfusion (capillary refill, skin warmth and colour) Pulse Blood pressure Cardiac rhythm	Assess circulation Attach cardiac monitor (consider defibrillator) Check blood pressure every 5 minutes until normal (outside Yellow Zone and Red Zone criteria)
IVC and/or pathology	Insert IV cannula, if trained and clinically indicated If unable to obtain IV access, insert intraosseous, if trained See pathology section
Signs of shock: tachycardia and CRT 3 seconds and over and/or abnormal skin perfusion and/or hypotension	If signs of shock present and/or SBP less than 90 mmHg, give 250 mL of sodium chloride 0.9% IV/intraosseous bolus Repeat every 10 minutes (up to 1000 mL) until SBP over 90 mmHg or signs of shock have resolved

Disability

Assessment	Intervention
ACVPU	If ACVPU shows reduced level of consciousness, continue to GCS, pupillary response and limb strength
GCS, pupillary response and limb strength	Obtain baseline and repeat assessment as clinically indicated
Pain	Assess pain. If indicated, give early analgesia as per analgesia section then resume A to G assessment

Exposure

Assessment	Intervention
Temperature	Measure temperature
Skin and mucous membrane inspection, including posterior surfaces	Check and document any abnormalities Consider progressive urticaria, angioedema or pallor

Fluids

Assessment	Intervention
Hydration status: last ate, drank, bowels opened, passed urine or vomited	Commence fluid balance chart
Nausea and/or vomiting	If present, see nausea and/or vomiting section

Glucose

Assessment	Intervention
BGL	Measure BGL, if clinically indicated If less than 4 mmol/L, consider hypoglycaemia protocol

Focused assessment

• No specific focused assessment. Use clinical judgement and A to G assessment to determine focused assessment.

Precautions and notes

• Sitting upright suddenly or standing during anaphylaxis can be fatal.
• Most reactions occur within 30 minutes of exposure but may be delayed several hours.
• Antihistamines have no role in treating or preventing respiratory or cardiovascular symptoms of anaphylaxis.
• Antihistamines primarily relieve cutaneous symptoms such as urticaria, itchiness and erythema.

Interventions and diagnostics

Specific treatment

All patients with anaphylaxis require escalation as per local CERS protocol

• Do not allow patient with anaphylaxis to walk, sit up or stand suddenly. It can be fatal.
• Treat patients supine or on their side.

Known asthma and/or wheeze

• Treat anaphylaxis first, including repeat doses of adrenaline.
• Follow patient's own management plan if available.
• Able to breathe via spacer: give 12 puffs of salbutamol 100 microg/puff MDI via spacer, every 20 minutes for up to 3 doses, if required.
• Unable to breathe adequately via spacer: give salbutamol 5 mg with 8–10 L of oxygen via nebuliser, every 20 minutes for up to 3 doses, if required.
• If anaphylaxis has resolved but wheeze persists, consider shortness of breath with history of asthma protocol.

Urticarial rash

• For symptomatic treatment once hemodynamically stable: give loratadine 10 mg, orally once daily.

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Analgesia

If pain score 1–6 (mild–moderate): give paracetamol 1000 mg orally once only.

If severe pain present, give analgesia and escalate as per local CERS protocol.

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Nausea and/or vomiting

If nausea and/or vomiting is present, give:

• metoclopramide 10 mg orally or IV/IM once only (over 20 years only)
• or ondansetron 4 mg orally or IV/IM. If symptoms persist after 60 minutes, repeat once, maximum dose 8 mg
• or prochlorperazine 5 mg orally once only or 12.5 mg IV/IM once only

Choice of antiemetic should be determined by cause of symptoms.

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Radiology

Not usually indicated. If there is concern for urgent radiology, escalate care as per local CERS protocol.

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Pathology

Not usually indicated. If there is concern for urgent pathology, escalate care as per local CERS protocol.

Medications

The shaded sections in this protocol are only to be used by registered nurses who have completed the required education.

Medications with contraindications or requiring dose adjustment are marked:

• ^H for patients with known hepatic impairment
• ^R for patients with known renal impairment.

Escalate to medical or nurse practitioner.

Evidence informed	Information was drawn from evidence-based guidelines and a review of latest available research. For more information, see the development process.
Collaboration	This protocol was developed by the ECAT Working Group, led by the Agency for Clinical Innovation. The group involved expert medical, nursing and allied health representatives from local health districts across NSW. Consensus was reached on all recommendations included within this protocol.
Currency	Due for review: Jan 2026. Based on a regular review cycle.
Feedback	Email ACI-ECIs@health.nsw.gov.au