Table 2.

Duration of observation following anaphylaxis; reproduced with permission from the 2021 Resuscitation Council UK guideline, Emergency treatment of anaphylaxis: Guidelines for healthcare providers¹

Consider fast-track discharge (after 2 hours observation from resolution of anaphylaxis) if all or the following:	A minimum of 6 hours observation after resolution of symptoms recommended if:	Observation for at least 12 hours following resolution of symptoms if any one of the following:
Good response (within 10–15 minutes) to a single dose of adrenaline given within 30 minutes of onset of reaction. and Complete resolution of symptoms. and The patient already has unused adrenaline auto-injectors (AAI) and has been trained how to use them. and There is adequate supervision following discharge.	Two doses of IM adrenaline needed to treat reaction.a or Previous biphasic reaction.	Severe reaction requiring >2 doses of adrenaline. or Patient has severe asthma or reaction involved severe respiratory compromise. or Possibility of continuing absorption of allergen eg slow-release medicines. or Patient presents late at night or may not be able to respond to any deterioration. or Patients in areas where access to emergency care is difficult.

In all cases, discharge must comply with National Institute for Health and Care Excellence clinical guidance CG134.⁵⁴

^aIt may be reasonable for some patients to be discharged after 2 hours, eg following a supervised allergy challenge in a specialist allergy setting. IM = intramuscular.