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False LA Allergy Vasovagal — ORE Part 1 MCQ

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EasyPharmacology & TherapeuticsFalse LA Allergy VasovagalORE Part 1

A patient requires a dental extraction and reports an allergy to a previous local anaesthetic injection. They recall becoming sweaty, nauseous and faint during the procedure, without rash, wheeze or facial swelling. What is the most likely explanation?

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Correct answer: A — A vasovagal reaction to the injection

**A is correct.** Sweating, nausea and feeling faint, with no rash, wheeze or swelling, are typical of a psychogenic vasovagal reaction associated with injection anxiety or pain. Such reactions are common around dental local anaesthetic administration and are not evidence of local anaesthetic allergy. Immediate allergy or anaphylaxis would be more likely to include urticaria, angioedema, bronchospasm, hypotension or other rapidly progressive systemic features. Latex allergy can also cause immediate allergic features, but the history does not suggest these. Methaemoglobinaemia from prilocaine presents with cyanosis, dyspnoea and reduced oxygen saturation rather than a brief faint episode. Cartridge-excipient anaphylaxis is similarly inconsistent with the described symptoms.

Reference: NHS Specialist Pharmacy Service. Managing reactions to dental local anaesthetic injections. Current guidance. https://www.sps.nhs.uk/articles/managing-reactions-to-dental-local-anaesthetic-injections/