Anaphylaxis: assessment and referral after emergency treatment

Anaphylaxis

Anaphylaxis is a serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death.

Severe anaphylaxis is characterised by potentially life-threatening compromise in airway, breathing or the circulation, and may occur without typical skin features or circulatory shock being present.

Biphasic anaphylaxis

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.

Idiopathic anaphylaxis

Denotes a form of anaphylaxis where no identifiable stimulus can be found. All known causes of anaphylaxis (including presentations associated with a delayed reaction, for example, alpha-gal allergy) must be excluded before this diagnosis can be reached.

Supervised allergy challenge

A clinically supervised test where increasing doses of a suspected allergen are given to confirm or rule out an allergy. It is considered the gold standard method in diagnosing food or drug allergy.

Suspected anaphylaxis

The diagnosis, prior to assessment by a specialist allergist, for people who present with symptoms of anaphylaxis.

In A&E departments a person who presents with the signs and symptoms of anaphylaxis may be classified as having a 'severe allergic reaction' rather than anaphylaxis. Throughout this guideline, anyone who presents with such signs and symptoms is classed as experiencing 'suspected anaphylaxis', and should be diagnosed as having 'suspected anaphylaxis'. The use of the adjective 'anaphylactic' should be reserved to describe 'anaphylactic shock' where circulatory shock occurs in the context of anaphylaxis.

Please see the NICE glossary for an explanation of terms not described above.