People have the right to be involved in discussions and make informed decisions about their care, as described in making decisions about your care.
Making decisions using NICE guidelines explains how we use words to show the strength (or certainty) of our recommendations, and has information about prescribing medicines (including off-label use), professional guidelines, standards and laws (including on consent and mental capacity), and safeguarding.
The following guidance is based on the best available evidence. The full guideline gives details of the methods and the evidence used to develop the guidance.
Document the acute clinical features of the suspected anaphylactic reaction (rapidly developing, life-threatening problems involving the airway [pharyngeal or laryngeal oedema] and/or breathing [bronchospasm with tachypnoea] and/or circulation [hypotension and/or tachycardia] and, in most cases, associated skin and mucosal changes).
Record the time of onset of the reaction.
Record the circumstances immediately before the onset of symptoms to help to identify the possible trigger.
After a suspected anaphylactic reaction in adults or young people 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.
After a suspected anaphylactic reaction in children 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.
Inform the person (or, as appropriate, their parent and/or carer) that a blood sample may be required at follow-up with the specialist allergy service to measure baseline mast cell tryptase.
Adults and young people aged 16 years or older who have had emergency treatment for suspected anaphylaxis should be observed for 6 to 12 hours from the onset of symptoms, depending on their response to emergency treatment. In people with reactions that are controlled promptly and easily, a shorter observation period may be considered provided that they receive appropriate post‑reaction care prior to discharge.
Children younger than 16 years who have had emergency treatment for suspected anaphylaxis should be admitted to hospital under the care of a paediatric medical team.
After emergency treatment for suspected anaphylaxis, offer people a referral to a specialist allergy service (age-appropriate where possible) consisting of healthcare professionals with the skills and competencies necessary to accurately investigate, diagnose, monitor and provide ongoing management of, and patient education about, suspected anaphylaxis.
After emergency treatment for suspected anaphylaxis, offer people (or, as appropriate, their parent and/or carer) an appropriate adrenaline injector as an interim measure before the specialist allergy service appointment.
Before discharge a healthcare professional with the appropriate skills and competencies should offer people (or, as appropriate, their parent and/or carer) the following:
information about anaphylaxis, including the signs and symptoms of an anaphylactic reaction
information about the risk of a biphasic reaction
information on what to do if an anaphylactic reaction occurs (use the adrenaline injector and call emergency services)
a brand-specific demonstration of the correct use of the adrenaline injector and when to use it, including advice that the person should lie down after using the adrenaline injector (or sit up if they are struggling to breathe) and should not stand up or change position suddenly, even if they feel better
a prescription for 2 further adrenaline injectors, with advice to carry the injectors with them at all times
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
information about patient support groups.
Each hospital trust providing emergency treatment for suspected anaphylaxis should have separate referral pathways for suspected anaphylaxis in adults (and young people) and children.
Anaphylaxis is a severe, life-threatening, generalised or systemic hypersensitivity reaction. It is characterised by rapidly developing, life-threatening problems involving: the airway (pharyngeal or laryngeal oedema) and/or breathing (bronchospasm with tachypnoea) and/or circulation (hypotension and/or tachycardia). In most cases, there are associated skin and mucosal changes.
After complete recovery of anaphylaxis, a recurrence of symptoms within 72 hours with no further exposure to the allergen. It is managed in the same way as anaphylaxis.
Denotes a form of anaphylaxis where no identifiable stimulus can be found. All known causes of anaphylaxis must be excluded before this diagnosis can be reached.
The diagnosis, prior to assessment by a specialist allergist, for people who present with symptoms of anaphylaxis.
In emergency departments a person who presents with the signs and symptoms of anaphylaxis may be classified as having a 'severe allergic' reaction rather than an 'anaphylactic' reaction. Throughout this guideline, anyone who presents with such signs and symptoms is classed as experiencing a 'suspected anaphylactic reaction', and should be diagnosed as having 'suspected anaphylaxis'.
Please see the NICE glossary for an explanation of terms not described above.