see also: [[Rat poison]], [[Warfarin, DOAC, heparin reversal]], [[DOAC overdose]] see: [Murray Tox - Warfarin](x-devonthink-item://DA1896AC-D57C-4A67-B2C7-65B1D27BB53E?page=403), [Austin Tox - warfarin guideline](x-devonthink-item://A84AE488-4A23-4DF3-A02A-86833E8F712B) > [!key points] > - Acute ingestion <0.5 mg/kg is unlikely to cause a clinically significant ↑ in INR and does not require further investigation > - **Paeds:** accidental ingestion of > 0.5mg/kg requires assessment in hospital > - risk of haemorrhage increases significantly with INR > 5 - most patients with acute overdose are *asymptomatic* at presentation - warfarin effect id delayed 24-48 hours post ingestion - bleeding more likely to occur in pts who have become over-anticoagulated while already on therapeutic dosing - pts with active bleeding require urgent [[Warfarin, DOAC, heparin reversal|anticoagulation reversal]] - large intentional overdoses may cause recurrent or prolonged elevation of INR after initial antidote administration and standard [[Warfarin, DOAC, heparin reversal#vitamin K|Vitamin K]] doses may not be adequate (similar seen in large [[Rat poison]] overdoses) *Risk factors for major bleeding related to elevated INR:* - older age - recent major bleed within 4 weeks - major surgery in prior 2 weks - [[thrombocytopaenia]] plt < 50 - liver disease - concurrent antiplatlet therapy # Treatment ![[Pasted image 20250127173454.png]] **General** - consider activated charcoal and MDAC if large OD and within 2 hours of ingestion PCC / FFP if bleeding may have delayed bleeding ## Acute overdose - [[paeds tox|children]] who accidentally ingest > 0.5mg/kg can safely be treated with vitamin K orally (eg 10 mg od for 3 days) without documenting serial INRs, as the risk of developing severe coagulopathy will be very low with this intervention. this will allow early discharge and remove the requirement for serial INR assays - follow up INR can be performed > 12 hours after the last dose of vitamin K to ensure that no coagulopathy is present if additional reassurance is required - other pts with intentional OD of warfain but no therapeutic requirement for anticoagulation are admitted for serial INR measurements and titrated doses of vitamin K - reasonable to consider tx w/ large doses of vitamin K orally eg 10mg BD - follow up INR at 48-72 hours including at least one INR > 12 hours post dosing with vitamin K to ensure coagulopahty has resolved - pts with a therapuetic requirement for anticoagulation are admitted for serial monitoring of INR and receive titrated vitamin K doses ## therapeutic over-anticoagulation - therapeutic over-anticoagulation can be managed as either an inpatient or an outpatient based on the INR level and the consideration of bleeding risk (see high risk factors list above) for the individual patient.