Chlorphenamine Allergic Reaction — MFDS Part 1 MCQ

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ModeratePharmacologyChlorphenamine Allergic ReactionMFDS Part 1

An adult develops a localised pruritic urticarial rash during dental treatment. The rash remains stable, and there is no facial, lip or tongue swelling, hoarseness, stridor, wheeze, hypotension or altered consciousness. While the patient is monitored, which drug is most appropriate for symptomatic relief of this mild allergic reaction?

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Reveal the answer and explanation

Correct answer: B — Chlorphenamine 4 mg orally

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

A is correct. The stable, localised urticaria without airway, breathing or circulatory compromise represents a mild allergic reaction rather than anaphylaxis. SDCEP states that dental practices may stock oral chlorphenamine 4 mg to aid management of mild allergic reactions; patients should be warned that it can cause drowsiness and should continue to be observed for progression. Intramuscular adrenaline is first-line when anaphylaxis causes, or threatens to cause, airway, breathing or circulatory compromise. Aspirin is used for suspected acute coronary syndrome, glucagon for severe hypoglycaemia when oral glucose cannot be given, and buccal midazolam for a prolonged or recurrent convulsion.

Reference: Scottish Dental Clinical Effectiveness Programme (SDCEP), Practice Support Manual, “Medical emergency drugs,” current 2026: https://www.psm.sdcep.org.uk/topics/medical-emergencies-and-life-support/medical-emergency-drugs/