A systemic type I (IgE mediated) life-threatening hypersensitivity reaction. 10-20% of cases may not have skin/mucosal changes (i.e. just bronchospasm or hypotension).

Initial actions

Immediately get help, call medical emergency team on 2222 (tell switchboard it is a medical emergency and the location) and remove allergen (i.e. stop any infusions).

Airway

• Secure airway
• If stridor/airway obstruction, adrenaline nebuliser (5ml 1:1000) and consider intubation

Breathing

• Apply sats probe
• Attach 15L/minute oxygen via a non-rebreather mask
• Bag-mask ventilation or intubation if apnoeic 
• If wheeze, salbutamol (5mg) and ipratropium (500mcg) nebulisers with oxygen
• ABG

Circulation

• Check blood pressure and apply 3-lead cardiac monitoring
• Secure IV access (2 large-bore IV cannulas) – get IO access if unable to estabish IV access
• IV fluids 500-1000ml 0.9% saline/Hartmann’s solution STAT fluid challenge initially (may need 3-5L IV fluids – give as fast as needed and titrate to BP)
• Take bloods (including mast cell tryptase) and blood gas

Further short-term management

• Document allergy on drug chart and event in notes
• Admit for observation (at least 6 hours post-adrenaline because biphasic reactions can occur)
• Consider oral non-sedating antihistamine
• Monitor ECG
• Further IV fluids if required

Longer-term management

• Educate patient
• Teach about self-injected adrenaline (Epipen)
• Medic alert bracelet 
• Refer to allergy clinic ± skin prick tests to identify allergens if unknown
• Clinical incident form if given allergic antibiotic

Reference: UK Resuscitation Council ‘Emergency treatment of anaphylactic reactions: Guidelines for healthcare providers’ 2021

Questions to test yourself

Try an OSCE station

1. Anaphylaxis
2. There are loads of OSCE stations for our subscribers available here