Vitamin K Injection for Epistaxis in Warfarin-Associated Coagulopathy
For epistaxis in patients on warfarin, vitamin K injection should NOT be used routinely—first-line management consists of local measures (nasal compression, vasoconstrictors, cautery, or packing), with vitamin K reserved only for life-threatening bleeding or when INR exceeds 10. 1
First-Line Management: Local Control Without Reversal
The American Academy of Otolaryngology strongly recommends attempting first-line interventions (nasal compression, topical vasoconstrictors, nasal cautery, and/or nasal packing) before administering vitamin K, withholding anticoagulation, or giving blood products for epistaxis in anticoagulated patients. 1
Good local control efforts are critical because reversal strategies carry significant risks, including thromboembolism and blood product exposure. 1
Even patients on warfarin with elevated INR can achieve hemostasis with proper local measures in most cases, avoiding the thrombotic risks associated with anticoagulation reversal. 1
When to Consider Vitamin K Administration
INR 4.5-10 Without Life-Threatening Bleeding
For patients with INR 4.5-10 and epistaxis that is controlled or controllable with local measures, the American College of Chest Physicians recommends AGAINST routine vitamin K use (Grade 2B). 1
Pooled analysis of four randomized trials showed no reduction in major bleeding rates between vitamin K and placebo groups (2% vs 0.8%) over 1-3 months, despite faster INR normalization with vitamin K. 1
Simply withholding warfarin and monitoring serial INR determinations is sufficient for most patients without active life-threatening bleeding. 2
INR >10 Without Life-Threatening Bleeding
For INR >10 with epistaxis controlled by local measures, consider oral vitamin K 2.5-5 mg in addition to holding warfarin, as the bleeding risk becomes clinically significant at this level (3.9% major bleeding rate at 90 days). 1, 2
The decision to administer vitamin K should factor in patient-specific bleeding risk factors including advanced age (>65 years), history of bleeding, renal failure, or concomitant antiplatelet drugs. 2
Life-Threatening Epistaxis
For life-threatening epistaxis with massive hemorrhage or hemodynamic instability, immediately administer 4-factor prothrombin complex concentrate (PCC) 25-50 U/kg IV PLUS vitamin K 5-10 mg by slow IV infusion over 30 minutes, targeting INR <1.5. 1, 2
PCC achieves INR correction within 5-15 minutes versus hours with fresh frozen plasma, making it the preferred agent for life-threatening bleeding. 2
Always co-administer vitamin K with PCC because factor VII in PCC has only a 6-hour half-life, requiring vitamin K to stimulate endogenous production of vitamin K-dependent factors. 2
Dosing Algorithm for Vitamin K
INR 4.5-10 without life-threatening bleeding: No vitamin K recommended; withhold warfarin only. 1
INR >10 without life-threatening bleeding: Oral vitamin K 2.5-5 mg. 2
Major bleeding (not life-threatening): IV vitamin K 5-10 mg by slow infusion over 30 minutes. 2
Life-threatening bleeding: IV vitamin K 10 mg PLUS 4-factor PCC 50 U/kg (for INR >6). 2
Route of Administration Considerations
Oral vitamin K is preferred for non-emergency situations due to lower risk of anaphylactoid reactions, which occur in 3 per 100,000 IV doses and can result in cardiac arrest. 2
IV vitamin K should be reserved exclusively for major or life-threatening bleeding and must be administered by slow infusion over 30 minutes to minimize anaphylaxis risk. 2, 3
The subcutaneous route is not recommended due to unpredictable absorption and cutaneous reactions. 4
Critical Pitfalls and Caveats
Excessive vitamin K (≥10 mg) creates warfarin resistance for up to a week, making re-anticoagulation difficult and potentially requiring heparin bridging. 2, 5
Vitamin K administration increases thrombotic risk during the recovery period, and thromboprophylaxis must be considered as early as possible after bleeding control. 2
The risk of thromboembolism from overcorrection appears to be in the same range as the risk of bleeding from over-anticoagulation, emphasizing the importance of judicious vitamin K use. 4
For patients with mechanical heart valves requiring urgent procedures, use low-dose vitamin K (1-2 mg) to avoid difficulty achieving therapeutic INR post-procedure. 2
Monitoring After Vitamin K Administration
Recheck INR 15-60 minutes after PCC administration to assess degree of correction. 2
For oral vitamin K, recheck INR within 24-48 hours to confirm appropriate reduction. 2
Monitor INR serially every 6-8 hours for the first 24-48 hours, as some patients require over a week to clear warfarin and may need additional vitamin K. 2