Overdose may result from accidental ingestion of rat poison (containing a warfarin-like substance) or overdose of warfarin used for therapeutic purposes.

Warfarin inhibits the production of coagulation factors in the liver.

Clinical features

  • Bleeding (can be life threatening) internal or from mucosae
  • Usually evident 24 hours after ingestion


  • Empty the stomach
  • Give activated charcoal 50 g if presenting early
  • Child: 25 g (50 g if severe)
  • Phytomenadione (vitamin K1) 5 mg IV slowly
  • Supportive treatment (IV fluids, blood transfusion, fresh frozen plasma if active bleeding)


  • Intoxication with rat poison may require prolonged treatment with vitamin K