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Updated: Jul 14, 2026

Doxycycline Loaded Collagen-Chitosan Composite Scaffold for the Accelerated Healing of Diabetic Wounds
Published on: August 21, 2021
Interaction of doxycycline and warfarin: an enhanced anticoagulant effect
1Mayo Clinic, Jacksonville, FL 32224, USA. Hasan.saiyid@mayo.edu
Purpose:
To highlight the importance of recognizing the increased anticoagulant effect of warfarin associated with use of doxycycline.
Design:
Case report.
Methods:
Clinical review describing initial presentation, course, and outcome of one patient who received oral doxycycline for corneal melt while on warfarin in a multi-specialty clinic.
Results:
Concomitant use of doxycycline and warfarin resulted in prominent ecchymosis of the upper extremities associated with a marked elevation in the international normalized ratio (INR = 6.5). Discontinuation of doxycycline resulted in reduction of INR to therapeutic levels (INR = 2.3).
Conclusions:
Doxycycline can enhance the anticoagulant effect of warfarin. This is likely due to competitive interaction for albumin binding and possibly inhibition of the cytochrome P-450 system. An increase in plasma levels of free warfarin may result in severe bleeding. It is important to recognize this potential interaction and obtain a complete medication profile prior to initiating doxycycline.
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