Anaphylaxis: assessment and referral after emergency treatment

  • NICE guideline
  • NG258
  • Published: 
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Period of observation

1.1.7

A suitably qualified and experienced healthcare professional should consider discharging the adult, young person or child after 2 hours of observation, starting from resolution of airway swelling and resumption of normal breathing and stable blood pressure and heart rate if:

  • there was a good response (within 5 to 10 minutes) to a single dose of intramuscular (IM) adrenaline given within 30 minutes of the onset of suspected anaphylaxis and

  • symptoms have completely resolved, and

  • the person already has 2 in-date adrenaline auto-injectors and knows how and when to use them, and

  • there is adequate supervision from an appropriate adult, if needed, following discharge. [2026, adapted from Resuscitation Council UK 2021 guidance]

1.1.8

Observe the adult, young person or child for a minimum of 6 hours after resolution of all symptoms if:

  • 2 doses of intramuscular (IM) adrenaline were needed to treat the anaphylaxis or

  • there is a history of biphasic reaction. [2026, adapted from Resuscitation Council UK 2021 guidance]

1.1.9

Observe the adult, young person or child for a minimum of 12 hours after resolution of all symptoms if:

  • the person had severe anaphylaxis requiring more than 2 doses of adrenaline, or

  • the person has severe asthma or had anaphylaxis that involved severe respiratory compromise, or

  • there is a possibility of continuing absorption of allergen, for example, slow-release medicines, or

  • the person presents out-of-hours, or

  • the person may not be able to respond in the event of a deterioration in their condition, or

  • the person would be discharged to a geographical area where access to emergency care is difficult. [2026, adapted from Resuscitation Council UK 2021 guidance]

1.1.10

A suitably qualified and experienced healthcare professional should consider discharging the adult, young person or child after 2 hours of observation from resolution of anaphylaxis following a supervised allergy challenge even if 2 doses of IM adrenaline were needed. [2026, adapted from Resuscitation Council UK 2021 guidance]