Metronidazole Dual Interaction — MFDS Part 1 MCQ

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EasyPharmacologyMetronidazole Dual InteractionMFDS Part 1

Which medicine that may be prescribed in dentistry is associated with both a disulfiram-like reaction with alcohol and potentiation of warfarin anticoagulation?

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Correct answer: C — Metronidazole

Metronidazole is the single best answer. Its UK SmPC advises avoiding alcohol during treatment and for at least 48 hours afterwards because of a possible disulfiram-like reaction. It can also potentiate warfarin-type oral anticoagulants, increasing the INR and bleeding risk; anticoagulation monitoring and possible warfarin dose adjustment may therefore be needed. Amoxicillin and other antibiotics can sometimes alter anticoagulation during infection, but amoxicillin is not associated with the specified alcohol reaction. Ibuprofen increases bleeding risk through its NSAID effects rather than producing this characteristic pair of interactions. Paracetamol and lidocaine likewise do not cause both effects. A mechanism for the alcohol reaction should not be asserted as established because it remains uncertain.

Reference: Electronic Medicines Compendium, Metronidazole 400 mg Tablets, Summary of Product Characteristics, section 4.5 Interactions, updated 30 April 2025. https://www.medicines.org.uk/emc/product/12817/smpc