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Updated: Aug 19, 2026

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Published on: May 31, 2016
Influence of warfarin on symptoms of fatigue: findings of a randomized trial
Michael J Kovacs1, Clive Kearon, Jim A Julian
1Department of Medicine, University of Western Ontario, London, Ontario, Canada. michael.kovacs@lhsc.on.ca
Background:
Some patients develop fatigue while taking warfarin, but causality is uncertain.
Objective:
To assess whether warfarin use is associated with fatigue.
Methods:
This investigation was a substudy of a randomized double-blind trial in 13 outpatient thromboembolism clinics. Subjects who had received one month of open-label warfarin therapy for venous thromboembolism due to a transient risk factor were randomly assigned to receive warfarin or placebo for 2 months and followed for another 9 months after stopping the study drug. Fatigue was measured using a Likert scale, and change of fatigue was measured by the patient's global rating.
Results:
In 87 subjects, the overall ratings of fatigue were 0.1 unit lower (95% CI 0.6 units lower to 0.4 units higher) while taking warfarin. Global rating for change in fatigue intensity showed no increase of fatigue with warfarin use.
Conclusions:
The short-term use of warfarin was not associated with symptoms of fatigue.
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