Anaphylaxis management¶
Emergency — act immediately
If anaphylaxis is suspected, do not delay treatment to confirm diagnosis.
Recognition¶
Anaphylaxis is likely if any ONE of the following:
- Acute onset illness with skin/mucosal involvement (urticaria, flushing, angioedema) AND at least one of: respiratory compromise, hypotension, or end-organ dysfunction
- Two or more of the following after exposure to a likely allergen: skin/mucosal involvement, respiratory compromise, hypotension, gastrointestinal symptoms
- Hypotension alone after known allergen exposure
Immediate management¶
1. Stop the drug / remove allergen¶
Cease infusion or remove SPT/IDT materials if possible.
2. Call for help¶
Activate emergency response — call 2222 (RPAH internal emergency).
3. Adrenaline — first-line treatment¶
Adrenaline is the ONLY first-line treatment
Do not delay adrenaline to administer antihistamines or corticosteroids.
Adrenaline 1:1000 (1 mg/mL) — intramuscular (IM), mid-outer thigh
| Patient weight | Dose | Volume (1:1000) |
|---|---|---|
| < 20 kg | 0.01 mg/kg | 0.01 mL/kg |
| 20–50 kg | 0.3 mg | 0.3 mL |
| > 50 kg | 0.5 mg | 0.5 mL |
- Route: IM, mid-outer thigh (through clothing if needed)
- Repeat: every 5 min if no improvement
- Pre-drawn adrenaline syringe must be available before commencing any IDT or challenge
4. Position¶
- Lay patient flat with legs elevated (unless respiratory distress — sit upright)
- Do not allow patient to stand or sit up suddenly
5. Oxygen¶
High-flow O₂ via non-rebreather mask.
6. IV access¶
Establish large-bore IV access if not already in situ. Give IV fluid bolus (NS 20 mL/kg) if hypotensive.
7. Adjunct medications (secondary — after adrenaline)¶
| Drug | Dose | Route | Purpose |
|---|---|---|---|
| Salbutamol | 5 mg nebulised | Inhaled | Bronchospasm |
| Promethazine | 25–50 mg (adult) | IM/IV slow | Antihistamine (H1) |
| Hydrocortisone | 200 mg (adult) | IV | Prevent biphasic reaction |
| Ranitidine | 50 mg (adult) | IV slow | Antihistamine (H2) |
Biphasic reaction¶
- Can occur 1–72 h after initial anaphylaxis (typically 8–12 h)
- All patients who receive adrenaline should be observed for minimum 4–6 hours
- Discuss extended observation or admission with AMO
Documentation¶
Record in patient notes: - Time of reaction onset - Signs and symptoms observed - Adrenaline dose, route, time, and response - All subsequent medications given - Vital signs before and after treatment - Outcome and disposition plan
References¶
- ASCIA Anaphylaxis guidelines: allergy.org.au
- Australian Prescriber Anaphylaxis wallchart