Adrenaline reaction after local anaesthetic — ORE Part 1 MCQ

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ModerateOral SurgeryAdrenaline reaction after local anaestheticORE Part 1

A 34-year-old patient develops palpitations, tremor and anxiety within one minute of receiving lidocaine with adrenaline for an upper premolar restoration. There is no urticaria, wheeze, hypotension or facial swelling. The symptoms settle within several minutes with reassurance. What is the most likely cause?

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Reveal the answer and explanation

Correct answer: D — Intravascular adrenaline effect

Explanation lettering: B = shown as A · E = shown as B · A = shown as E

D is correct. A brief onset immediately after injection, with palpitations, tremor and anxiety that resolve with reassurance, is characteristic of an acute adrenaline effect after inadvertent intravascular uptake. The UK SmPC notes that an intravascular injection may cause a temporary rise in heart rate and that systemic reactions can occur within seconds to minutes. Lidocaine allergy and latex anaphylaxis would be expected to produce features such as urticaria, angioedema, wheeze or hypotension; these are specifically absent. Hypoglycaemia is not temporally linked to the injection and would more typically include sweating, hunger, confusion or impaired consciousness. Significant local-anaesthetic toxicity is less likely because early neurological warning features such as circumoral paraesthesia, tongue numbness, tinnitus or visual disturbance are not described.

Reference: Electronic Medicines Compendium. Lidocaine 20 mg/ml (2% w/v) with Adrenaline (Epinephrine) 1:200,000 solution for injection — Summary of Product Characteristics, sections 4.4, 4.8 and 4.9, updated February 2026. https://www.medicines.org.uk/emc/product/101881/smpc