Observation and patient disposition after warfarin poisoning

Admit all patients for at least 48 hours of INR monitoring with:

• deliberate warfarin poisoning
• any ingestion of more than 0.5 mg/kg of warfarin
• a raised international normalised ratio (INR)
• any bleeding complications.

Discharge them once:

• bleeding is controlled
• INR is less than 2 (or within the target range if the patient taking warfarin therapeutically)
• at least 12 hours have elapsed since their last dose of phytomenadione (vitamin K₁).

Patients who have unintentionally ingested less than 0.5 mg/kg warfarin do not need investigations and can be discharged.

Stop any drugs that inhibit CYP2C9 and may have contributed to warfarin toxicity.