Suspected anaphylaxis
Sudden illness after exposure to a possible trigger (food, drug, sting, contrast). Stop any suspected IV drug or infusion at once.
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Emergency MedicineEmergency
Anaphylaxis: Acute Management (ASCIA 2026; GA²LEN 2024 criteria)
Anaphylaxis: Acute Management (ASCIA 2026; GA²LEN 2024 criteria): Suspected anaphylaxis → Anaphylaxis possible? → Give IM adrenaline (epinephrine) now →...
Pathway Overview
16 steps
Algorithm Steps
16 total
01Start 02Decision Anaphylaxis possible?
Clinical diagnosis; do not wait for tests. Yes: skin signs plus breathing, circulation or persistent severe GI signs; or sudden low BP, bronchospasm or upper airway obstruction, even with no skin signs; or abdominal pain or vomiting after an insect sting. Infant or child: pale and floppy; fast heart rate first, low BP late. If in doubt, give adrenaline.
- Skin or mucosal signs PLUS breathing, circulation or persistent severe GI symptoms
- OR sudden low BP, bronchospasm or upper airway obstruction, even with NO skin signs
- Sudden wheeze in a person with asthma and allergy: treat as anaphylaxis
- Insect sting: abdominal pain or vomiting is a sign of anaphylaxis
- Infant or child: pale and floppy, drooling, irritability, somnolence, hypotonia or mottled skin; persistent fast heart rate comes first, low BP comes late
- If Yes
03Action Give IM adrenaline (epinephrine) now
Outer mid-thigh. No absolute contraindication. 1 mg/mL (1:1000): 0.01 mg/kg (0.01 mL/kg), max 0.5 mg. Pregnancy: same dose, do not withhold. Under anaesthesia or sedation: follow the ANZAAG-ANZCA perioperative guideline.
- Adult or child 50 kg or more: 0.5 mg (0.5 mL of 1 mg/mL)
- Repeat every 5 min if no or poor response
- Infant under 7.5 kg: 0.1 mL of 1 mg/mL (ASCIA dose table; smaller volumes are hard to measure)
- Device (AU): 150 microgram for 7.5-20 kg; 300 microgram for 20 kg or more; 500 microgram device option for 50 kg or more
- Nasal device (neffy): 1 mg for 15-30 kg (age 4 years or more); 2 mg for 30 kg or more
04Action Lay flat. Do not let the patient stand or walk
Legs raised if low BP. Breathing hard: sit with legs out. Pregnant, vomiting or unconscious: on the side (pregnant: left side).
- Hold young children flat, not upright or over a shoulder
- Stay flat even if recovered: move by stretcher or wheelchair with legs out
- Remove trigger if quick: stop IV drug or infusion; flick out sting; tick: freeze it and let it drop off, do not pull it out. Do not delay adrenaline
05Action Call for help and give supportive care
Resuscitation team (000 outside hospital). Monitor SpO2, BP, ECG.
- Give oxygen
- IV or IO access. Low BP: sodium chloride 0.9% 10-20 mL/kg IV rapidly; repeat as needed
- Unresponsive or not breathing normally: start CPR (ANZCOR)
06Decision Improving 5 min after adrenaline?
Check breathing, BP, perfusion and conscious state
- If Yes
07Action Improving: adjuncts for remaining symptoms only
Never instead of adrenaline. Do not give injectable promethazine or sedating antihistamines.
- Persistent wheeze: salbutamol 8-12 puffs of 100 microgram by spacer, or 5 mg nebulised
- Hives or itch only: oral non-sedating antihistamine (e.g. cetirizine, loratadine)
- Persistent wheeze: consider prednisolone 1 mg/kg oral (max 50 mg) or hydrocortisone 5 mg/kg IV (max 200 mg); benefit unproven
- Antihistamines do not treat breathing or circulation problems
08Action Serum mast cell tryptase
Supports the diagnosis later. Never delay treatment for it. Child: only if the diagnosis is in doubt or on paediatric allergy specialist advice.
- First sample as soon as possible after onset, once treatment has started
- Repeat at about 1-4 h after onset
- Baseline sample 24 h or more after recovery
- A normal tryptase does not exclude anaphylaxis
09Action Observe at least 4 h after the last adrenaline dose
Relapse or biphasic reaction can occur (3-20%, within 48 h). No standing or walking until stable: at least 1 h after 1 dose, 4 h after more than 1 dose. Symptoms return: give IM adrenaline again at once and treat as not improving.
- Overnight: severe or refractory reaction (repeated adrenaline, IV fluids or infusion)
- Overnight: past severe, refractory or biphasic anaphylaxis
- Overnight: severe asthma, arrhythmia, mastocytosis or other mast cell disorder
- Overnight: lives alone, remote from care, or presents late in the evening
10Action Discharge planning
Adrenaline device, action plan, specialist referral. Return or call 000 if symptoms recur.
- Prescribe and, if possible, dispense an adrenaline device; teach with a trainer device
- Give an ASCIA Action Plan for Anaphylaxis and teach how to use it
- Refer all patients to a clinical immunology/allergy specialist
- Asthma: review control before discharge; give adrenaline first for sudden breathing difficulty
11Outcome Resolved: discharge with plan
Symptoms settled after the observation period
If No12Action Not improving: repeat IM adrenaline
Same dose, other thigh, every 5 min. Infants: more than 2 doses can cause high BP and fast HR; use BP to guide doses. On a beta-blocker: adrenaline may work less well; keep dosing and get senior help.
- Call ED senior, ICU or anaesthetics now
- Stridor: nebulised adrenaline 5 mL of 1 mg/mL (1:1000), in addition to IM; consider early intubation
- Low BP: repeat sodium chloride 0.9% 10-20 mL/kg IV rapidly
- Wheeze: salbutamol and ipratropium nebulised with oxygen
13Decision Still unwell after 2 doses of adrenaline?
Persisting breathing or circulation problems despite 2 doses = refractory anaphylaxis. No (improving after dose 2): go to adjuncts and observation.
- If Yes
14Action Refractory: start IV adrenaline infusion
With senior or ICU help. Dedicated line. IV adrenaline bolus: not recommended, except peri-arrest (see details). On a beta-blocker: consider glucagon. No infusion possible: keep giving IM adrenaline every 5 min and arrange transfer to a centre with critical care.
- ED or tertiary: 1 mg (1 mL of 1 mg/mL) in 100 mL sodium chloride 0.9% (10 microgram/mL); start 0.5 mL/kg/h (about 0.1 microgram/kg/min) by pump; titrate to response
- Keep giving IM adrenaline every 5 min until the infusion runs
- Continuous ECG and SpO2, frequent BP; not on the BP cuff arm
- Non-tertiary: 1 mg in 1000 mL sodium chloride 0.9% (1 microgram/mL), start 5 mL/kg/h, with senior advice; temporary use only (risk of fluid overload)
- IV adrenaline bolus: not recommended. Only an experienced clinician in a specialist setting or peri-arrest (school-age child or adult): 1 microgram/kg (max 50 microgram) over 1-2 min
- Beta-blocker, refractory: glucagon IV; adult 1-2 mg every 5 min; child 40 microgram/kg (max 1 mg)
- Low BP despite infusion: fluid boluses and a second vasopressor (e.g. noradrenaline) with ICU; cardiac arrest: ANZCOR ALS
15Outcome ICU admission
Refractory anaphylaxis needs critical care. Before discharge: tryptase, adrenaline device, ASCIA Action Plan and allergy specialist referral.
If No- Path rejoins step 07Shared downstream outcome
If No16Action Anaphylaxis unlikely: consider other causes
Reassess often. Give IM adrenaline at once if breathing or circulation signs appear.
- Hives or lip or face swelling only (no tongue or throat swelling): mild to moderate allergic reaction; observe for progression
- Vasovagal episode (pallor, slow pulse, settles lying flat). A slow pulse does not exclude anaphylaxis (late shock, insect sting, beta-blocker)
- Panic attack, vocal cord dysfunction
- Angioedema without hives: consider ACE-inhibitor or hereditary angioedema
- Path rejoins step 02Shared downstream outcome
Guideline Source
ASCIA Guidelines: Acute Management of Anaphylaxis (2026); GA²LEN 2024 anaphylaxis consensus report (criteria, IM dosing)
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adrenaline IM is first line. Never delay it for antihistamines, steroids, positioning or tests.
- Doses and devices follow ASCIA 2026 (Australia and New Zealand). Use your local adrenaline infusion protocol where one exists.
- Beta-blocker use can make anaphylaxis refractory to adrenaline.
- Anaphylaxis under anaesthesia: use the ANZAAG-ANZCA perioperative guideline.
- Does not cover allergen immunotherapy, drug challenges or hereditary angioedema.
Contraindicated Populations
Hereditary or ACE-inhibitor angioedema without anaphylaxis (bradykinin-mediated; not treated by this pathway)
Applicable Regions
AUNZUSEUInternational
AU: ASCIA 2026: IM adrenaline 1 mg/mL, 0.01 mg/kg, max 0.5 mg. TGA-registered devices: EpiPen Jr and Jext Jr 150 microgram, EpiPen and Jext 300 microgram, Anapen 500 500 microgram, neffy 1 mg and 2 mg nasal. Use ASCIA Action Plans.
EU: Several auto-injector brands and strengths are available; follow national product information.
NZ: ASCIA guidelines apply. Check local device funding (Pharmac).
US: Auto-injectors per US labelling: 0.1 mg for 7.5-15 kg, 0.15 mg for 15-30 kg, 0.3 mg for 30 kg or more. Nasal epinephrine (neffy, age 4 years or more): 1 mg for 15-30 kg, 2 mg for 30 kg or more.
International: If no device: IM adrenaline 1 mg/mL (1:1000) by ampoule and syringe, 0.01 mg/kg, max 0.5 mg.
Version 2Next review: 2027-09-30
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Frequently Asked Questions
What is the Anaphylaxis: Acute Management (ASCIA 2026; GA²LEN 2024 criteria)?
The Anaphylaxis: Acute Management (ASCIA 2026; GA²LEN 2024 criteria) is a emergency clinical algorithm for Emergency Medicine. It provides a structured decision tree to guide clinical decision-making, based on ASCIA Guidelines: Acute Management of Anaphylaxis (2026); GA²LEN 2024 anaphylaxis consensus report (criteria, IM dosing).
What guideline is the Anaphylaxis: Acute Management (ASCIA 2026; GA²LEN 2024 criteria) based on?
This algorithm is based on ASCIA Guidelines: Acute Management of Anaphylaxis (2026); GA²LEN 2024 anaphylaxis consensus report (criteria, IM dosing).
What are the limitations of the Anaphylaxis: Acute Management (ASCIA 2026; GA²LEN 2024 criteria)?
Known limitations include: Adrenaline IM is first line. Never delay it for antihistamines, steroids, positioning or tests.; Doses and devices follow ASCIA 2026 (Australia and New Zealand). Use your local adrenaline infusion protocol where one exists.; Beta-blocker use can make anaphylaxis refractory to adrenaline.; Anaphylaxis under anaesthesia: use the ANZAAG-ANZCA perioperative guideline.; Does not cover allergen immunotherapy, drug challenges or hereditary angioedema.. Individual patient factors may require deviation from these recommendations.
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