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Fluconazole and warfarin — GPhC CRA MCQ

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HardDrug InteractionsFluconazole and warfarinGPhC CRA

A 62-year-old woman taking warfarin asks to buy fluconazole 150mg for thrush. Her INR was 3.4 yesterday, and she has noticed gum bleeding when brushing. She has used fluconazole before without contacting her anticoagulation clinic. What is the most important interaction to flag?

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

Fluconazole can potentiate warfarin and raise INR. The current INR is already high and gum bleeding suggests clinically relevant anticoagulation effect. The pharmacist should avoid OTC supply and refer for prescriber or anticoagulation clinic advice.

Reference: BNF