Warfarin overdose successfully treated using prophylactic vitamin K infusion without severe coagulopathy: A case report

Background: Warfarin, a vitamin K antagonist, is widely used for preventing and treating thromboembolic diseases. While guidelines exist for managing elevated prothrombin time-international normalized ratio (INR) in patients on warfarin, the treatment for warfarin overdose in these patients is yet to be standardized. Case Presentation: A 41-year-old woman ingested 230 mg of warfarin with suicidal intent, along with other medications. Initially unconscious, her INR was 1.0, and laboratory results were normal. Prophylactic continuous menaquinone-4, vitamin K2, injections were administered before the INR increased. After stopping vitamin K2 72 h later, her INR rose to 1.8, but she recovered without severe coagulopathy or bleeding, despite a high initial warfarin concentration. Conclusion: This is the first case of warfarin overdose managed with prophylactic vitamin K2 injections before INR elevation, successfully preventing severe complications. Prophylactic vitamin K infusion may be a practical approach for warfarin overdose treatment in non-dependent patients.