What is the maximum recommended dose of vitamin K (phytonadione) for an adult?

Maximum Recommended Dose of Vitamin K for Adults

The maximum recommended single dose of vitamin K (phytonadione) for adults is 10 mg, with higher doses (up to 25-50 mg) reserved only for rare, severe cases of anticoagulant-induced bleeding, though doses exceeding 10 mg can create a prothrombotic state and should be avoided in most clinical situations. 1, 2, 3

Standard Maximum Dosing by Clinical Scenario

Emergency Anticoagulation Reversal

• Maximum single dose: 10 mg IV administered by slow infusion over 30 minutes to minimize anaphylactoid reaction risk (approximately 3 per 100,000 doses) 1, 2, 3
• For life-threatening warfarin-associated bleeding, combine 10 mg IV vitamin K with four-factor prothrombin complex concentrate for rapid INR correction 2, 3
• Do not exceed 10 mg per dose as higher amounts induce a prothrombotic state and prevent re-anticoagulation for days 1

Anticoagulant-Induced Prothrombin Deficiency

• Initial dose: 2.5 to 10 mg, or up to 25 mg in rare instances 3
• In exceptional circumstances, 50 mg may be required, though this represents the absolute upper limit 3
• The FDA label specifies these higher doses (25-50 mg) are for rare, severe cases only 3

Rate of Administration

• Never exceed 1 mg per minute when administering intravenously 3
• Slow infusion over 30 minutes is recommended to minimize anaphylactoid reactions 1, 2

Context-Specific Maximum Doses

Parenteral Nutrition

• Weekly IV supply of 250-500 mcg (0.25-0.5 mg) phylloquinone from lipid emulsions is sufficient for maintenance 4, 2
• Adult multivitamin preparations provide additional 150 mcg (0.15 mg) to maintain carboxylation status 4, 2
• Caution: Doses >150 mcg may cause vitamin K antagonist resistance in patients on warfarin 4, 2

Bariatric Surgery Patients

• For vitamin K deficiency: 10 mg IM or subcutaneous, followed by 1-2 mg/week parenterally or orally 4
• After biliopancreatic diversion: 300 mcg (0.3 mg) daily as part of routine supplementation 4

Cystic Fibrosis Patients

• Adults: 1-10 mg/day depending on age and risk factors 4
• Higher doses may be considered for those with documented low vitamin K levels or on long-term antibiotics 4
• No known adverse effects from phylloquinone supplementation, making toxicity not a concern 4

Liver Disease

• 10 mg IV or oral as a diagnostic/therapeutic trial, with INR reassessment after 12-24 hours 1
• A decrease in INR ≥0.5 within 24-72 hours confirms vitamin K deficiency component 1
• Vitamin K has minimal efficacy in decompensated chronic liver disease when hepatic synthetic function is severely impaired 1

Critical Safety Considerations

Why 10 mg Is the Practical Maximum

• Doses exceeding 10 mg create a prothrombotic state and prevent effective re-anticoagulation for several days 1
• The risk-benefit ratio favors lower doses, as vitamin K takes >12 hours to begin correcting hemostatic defects 1
• In a study of mainly cirrhotic patients receiving 10 mg IV daily for 3 days, the overall adjusted INR decrease was only 0.3, suggesting minimal clinical impact of repeated high doses 5

Route-Specific Concerns

• Subcutaneous administration is ineffective in correcting coagulopathy in liver disease 1
• IV administration carries anaphylactoid risk (3 per 100,000 doses) with potential for cardiac arrest, severe hypotension, arrhythmias, dyspnea, or bronchospasm 1
• Oral administration shows similar INR reduction by 24 hours compared to IV, though IV has more rapid onset 2, 6

Common Pitfalls to Avoid

Overcorrection Risk

• High-dose IV vitamin K (>5 mg) causes overcorrection (INR <2.0) more frequently than lower doses 7
• For INR 6-10, use 0.5 mg IV or 2.5 mg oral; for INR >10, use 1 mg IV or 5 mg oral 3, 7
• Oral doses of 1-2.5 mg reduce INR from 5.0-9.0 to 2.0-5.0 within 24-48 hours without overcorrection 8

Inappropriate Use in Liver Disease

• Routine correction of elevated INR with vitamin K is not supported by evidence in chronic liver disease without active bleeding 1
• Vitamin K is only effective when true deficiency exists (prolonged antibiotics, malnutrition, cholestasis), not in hepatic synthetic dysfunction 1
• Factors associated with poor response include higher body weight, presence of cirrhosis, and higher bilirubin levels 5

Monitoring Requirements

• Re-check INR 12-24 hours after administration 1, 3
• If INR remains abnormal, monitor every 6-8 hours for the next 24-48 hours 1
• If prothrombin time has not shortened satisfactorily in 6-8 hours after parenteral administration, repeat the dose 3

Algorithm for Dose Selection

For warfarin over-anticoagulation without bleeding:

• INR 5-9: 1-2.5 mg oral 8, 9
• INR >10: 5 mg oral 8, 9

For warfarin-associated bleeding:

• Minor bleeding: 2.5-5 mg IV 3
• Major bleeding: 10 mg IV (maximum) + prothrombin complex concentrate 1, 2, 3

For suspected vitamin K deficiency in liver disease:

• Diagnostic/therapeutic trial: 10 mg IV or oral, reassess INR in 12-24 hours 1

For maintenance in special populations:

• Parenteral nutrition: 150-500 mcg weekly 4, 2
• Cystic fibrosis: 1-10 mg daily 4
• Post-bariatric surgery: 0.3 mg daily (BPD) or as needed 4