People over-anticoagulated with warfarin who have an INR between 4.5 and 10 are at increased risk of bleeding, but is the administration of vitamin K an effective and safe strategy to adopt if there is no active bleeding? A systematic review of relevant randomized controlled trials yielded six studies (1074 participants) for consideration. Pooled estimates indicate a non-significant increased risk of mortality (RR = 1.42; 95% confidence interval [CI], 0.62-2.47), bleeding (RR = 2.24; 95% CI, 0.81-7.27), and thromboembolism (RR = 1.29; 95% CI, 0.35-4.78) after the use of vitamin K, as well as a non-significant increase in the likelihood of reaching goal INR afterwards RR = 1.95; 95% CI, 0.88-4.33). On balance, this suggests that giving vitamin K administration in addition to holding warfarin probably adds little and may even be counterproductive. Read more here