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Metronidazole warfarin — GPhC CRA MCQ

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ModerateInfectionsMetronidazole warfarinGPhC CRA

A patient taking warfarin is prescribed metronidazole for dental infection. What is the most important interaction to flag?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Metronidazole can increase warfarin effect and bleeding risk

Metronidazole can potentiate warfarin and raise INR. In this scenario, the pharmacist should prioritise safe supply, appropriate counselling and timely referral or clarification where needed. This is the single best answer because the other options would either delay assessment, ignore a clinically significant risk, or create an unsafe legal or professional outcome.

Reference: BNF