This institutional review board–approved retrospective cohort study evaluated the impact of intravenous versus subcutaneous phytonadione on length of stay in hospitalized patients requiring urgent warfarin reversal. All patients were 18 years or older, on warfarin therapy with an international normalized ratio (INR) between 3.1 and 10.0, and had warfarin therapy restarted at discharge. Patients who received intramuscular or oral phytonadione, phytonadione by more than 1 route, fresh frozen plasma, or any other blood products containing clotting factors, patients with active or severe liver disease, and patients who received other forms of anticoagulation were excluded. A total of 4425 patients receiving phytonadione were evaluated and 79 patients were included. Baseline characteristics were similar between the intravenous and subcutaneous groups, including mean age, gender, warfarin indication, Charlson comorbidity index, and indication for phytonadione. Geometric mean length of stay in the intravenous group was 211.7 hours compared with 191.0 hours in the subcutaneous group (P = 0.47). Though intravenous phytonadione administration resulted in significantly lower INRs at all time points <36 hours, geometric mean time to restart of warfarin therapy was not impacted (66.3 hours vs. 64.1 hours, P = 0.72). Despite demonstrating significantly greater INR reductions, hospital length of stay and time to restart of warfarin therapy were not improved with the administration of intravenous over subcutaneous phytonadione.