ModerateAntifungals, triazole derivatives×Vitamin K antagonist anticoagulants
Updated · Methodology
Mechanism
Fluconazole moderately inhibits CYP2C9, which clears the more potent S-warfarin, and also CYP3A4 (fluconazole and warfarin labels). The warfarin effect increases: prothrombin time was prolonged up to 2-fold during co-administration (fluconazole SmPC). Bleeding events have been reported with this combination.
Symptoms
Bruising, nosebleeds, blood in the urine, black tarry stools and gastrointestinal bleeding, with a prolonged prothrombin time and a rising INR.
Management
The combination is not contraindicated but needs frequent coagulation checks. While both drugs are taken, monitor prothrombin time carefully and adjust the warfarin dose if needed (fluconazole SmPC). The Spanish warfarin SmPC requires close coagulation control whenever a concomitant medicine is added or stopped, and the US warfarin label (FDA) asks for close INR monitoring when any antifungal is started or stopped. So check the INR more often after the fluconazole course ends as well.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Jantoven (warfarin sodium tablets) – Prescribing Information (2025)– FDA, DailyMed SPL, Upsher-Smith Laboratories, разделы 5.1, 7.1 и 7.3
- AEMPS: Ficha técnica: Fluconazol (nº registro 67929), sección 4.5 (2026)– AEMPS, CIMA, nº registro 67929, revisión 10/2026, sección 4.5
- FDA: Diflucan (fluconazole) prescribing information (2026)– FDA Diflucan label, DailyMed setid f694c617-3383-416c-91b6-b94fda371204, revised 04/2026, Contraindications and Drug Interactions
- AEMPS: Ficha técnica: Warfarina (Aldocumar 5 mg) (nº registro 63064), sección 4.5 (2023)– AEMPS, CIMA, nº registro 63064, revisión 01/2023, sección 4.5
- AEMPS: Ficha técnica: Fluconazol (Diflucan 100 mg) (nº registro 58804), secciones 4.4 y 4.5 (2024)– AEMPS, CIMA, nº registro 58804, revisión 07/2024, secciones 4.4 y 4.5