Red flags
- Stridor, upper airway swelling
- Persistent hypotension
- Biphasic reaction risk
First steps
- Remove trigger
- Adrenaline 0.5 mg IM (anterolateral thigh) — repeat q5 min
- Lie flat with legs raised (sit up if resp distress)
- High-flow O₂
- IV crystalloid 500-1000 mL
Key investigations
- Serum tryptase at 1-2 h and 24 h
- Consider ABG if resp compromise
Differentials
- Vasovagal
- Panic attack
- Acute severe asthma
- ACE-i angioedema
Initial management
- Second-line: chlorphenamine 10 mg IV, hydrocortisone 200 mg IV, nebulised salbutamol/ipratropium
- Refractory: adrenaline infusion 0.05-1 mcg/kg/min, glucagon if on β-blocker
- Observe ≥6 h (biphasic risk)
Referral
- Allergist follow-up
- EpiPen × 2 + written action plan on discharge
AI clinical assessment
Enter patient details to generate evidence-based guidance.
This tool is for educational and clinical support only. It does not replace professional medical judgment or institutional protocols.
