At a Glance - Acute anaphylaxis

Epidemiology 

- Acute anaphylaxis is rare but life-threatening.

- Incidence is increasing, with female preponderance.

Pathophysiology

- Usually type-1 IgE-mediated hypersensitivity.

Aetiology

- Foods: dairy products, nuts, seafood and fruits.

- Drugs: antibiotics, opioid analgesics and NSAIDs.

- Wasp or bee stings.

- Miscellaneous causes include latex and exercise, and it can also be idiopathic.

Clinical features

- Feeling of impending doom.

- Respiratory features include laryngeal oedema, stridor and bronchospasm.

- Cardiovascular features include palpitations, chest pain and loss of consciousness.

- Skin features include pruritus, urticaria and angio-oedema.

- Gastrointestinal features include lip and tongue swelling, nausea and vomiting, abdominal pain and diarrhoea.

- Rhino-conjunctivitis.

Investigations

- Mast cell tryptase is the only test indicated at the time of reaction to confirm the diagnosis.

- Subsequent investigations are directed at detecting the trigger agent.

Management

- Acute management involves adrenaline IM, oxygen, parenteral hydrocortisone and parenteral chlorpheniramine.

- Admit to hospital.

- Subsequent management involves identifying the trigger and advising on avoidance.

- Prescribe EpiPen and educate patient about how and when to use it.

- Recommend a Medic Alert bracelet/necklace.

Key features

- Death is common in the elderly and asthmatics.

Contributed by Dr Aziz Sheikh, professor of primary care research and development, Division of Community Health Sciences, GP Section, University of Edinburgh.

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