Augmentin-Warfarin Interaction Guidelines

Mechanism and Clinical Evidence

• The American Heart Association acknowledges that gut microbiome disruption by Augmentin (amoxicillin/clavulanate) alters vitamin K-producing intestinal flora, potentiating warfarin's anticoagulant effects 1

Management and Monitoring

• The American College of Cardiology recommends documenting baseline INR if a patient has been stable on warfarin before prescribing Augmentin, and considering alternative antibiotics if clinically appropriate 1
• Close monitoring of INR is advised when initiating Augmentin in warfarin patients, with checks within 3-4 days of starting Augmentin 1
• For high-dose Augmentin (≥10 g/day), consider preemptive warfarin dose reduction of 25% and monitor INR every 2-3 days 1
• After completing Augmentin, continue monitoring INR for 3-7 days as changes may persist, and document the interaction and INR response for future reference 2