Anaphylaxis: assessment and referral after emergency treatment: Draft for consultation

Document the acute clinical features of suspected anaphylaxis (rapidly developing, life-threatening problems involving the airway [pharyngeal or laryngeal oedema] or breathing [bronchospasm with tachypnoea] or circulation [hypotension or tachycardia] and, in most cases, associated skin and mucosal changes). [2011]

Record the time of onset of suspected anaphylaxis. [2011]

Record the circumstances immediately before the onset of suspected anaphylaxis to help to identify the possible trigger. [2011]

After suspected anaphylaxis in an adult or young person aged 16 years or older, take timed blood samples for mast cell tryptase testing as follows:

• a sample as soon as possible after emergency treatment has started

• a second sample ideally within 1 to 2 hours (but no later than 4 hours) from the onset of symptoms. [2011]

After suspected anaphylaxis in a child younger than 16 years, consider taking blood samples for mast cell tryptase testing as follows if the cause is thought to be venom-related, drug-related or idiopathic:

• a sample as soon as possible after emergency treatment has started

• a second sample ideally within 1 to 2 hours (but no later than 4 hours) from the onset of symptoms. [2011]

Inform the person (or, as appropriate, their parent or carer) that a blood sample may be required at follow-up with the specialist allergy service to measure baseline mast cell tryptase. [2011]

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 adrenaline given within 30 minutes of the onset of suspected anaphylaxis and

• symptoms have completely resolved, and

• the person already has a supply of prescribed adrenaline auto-injectors and knows how to use them, and

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

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 guidance]

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 may not be able to seek help in response to 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 guidance]

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 guidance]

Admit children under 16 years who cannot be discharged under the care of a paediatric medical team. [2026]

After emergency treatment for suspected anaphylaxis, offer the adult, young person or child (or their parent or carer, as appropriate) 2 adrenaline auto-injectors to use if needed and as a safety measure before the specialist allergy service appointment, unless the anaphylaxis was due to a drug allergy and the drug can be easily avoided (see NICE's guideline on drug allergy). [2026]

Each hospital trust providing emergency treatment for suspected anaphylaxis should have separate referral pathways for suspected anaphylaxis in adults, young people and children. [2011]

Before discharge a healthcare professional with the appropriate skills and competencies should offer the adult, young person or child (or their parent or carer, as appropriate) the following:

• information about anaphylaxis, including the signs and symptoms of anaphylaxis

• information about the risk of a biphasic reaction

• advice about how to avoid the suspected trigger (if known)

• information about the need for referral to a specialist allergy service and the referral process

• a prescription for 2 further adrenaline auto-injectors with advice to carry the injectors with them at all times, unless the anaphylaxis was due to a drug allergy and the drug can be easily avoided (see recommendation 1.4.3)

• information on what to do if anaphylaxis occurs (use the adrenaline auto-injector and call emergency services)

• a brand-specific demonstration of the correct use of the adrenaline auto-injector and when to use it, including advice that the person should lie down after using the injector (or sit up if they are struggling to breathe) and should not stand up or change position suddenly, even if they feel better

• information about patient support groups. [2011, amended 2026]