Vitamin K is NOT indicated for anaphylaxis treatment
Vitamin K does not treat anaphylaxis—it causes anaphylaxis. The question appears to conflate two separate clinical scenarios: treating anaphylaxis (which requires epinephrine) versus reversing anticoagulation in a patient who happens to be experiencing anaphylaxis from vitamin K itself.
If the Question is About Treating Anaphylaxis
Epinephrine 0.3-0.5 mg intramuscularly in the anterolateral thigh is the only first-line treatment for anaphylaxis, regardless of anticoagulation status. 1, 2
- Epinephrine should be administered immediately upon recognition of anaphylaxis, as delays can be fatal 1, 2
- The pediatric dose is 0.01 mg/kg intramuscularly 2
- No other medication has life-saving effects across multiple organ systems in anaphylaxis 1
- Anticoagulation status does not change this recommendation—the risk of death from untreated anaphylaxis far exceeds bleeding risk from a single IM injection 1
If the Question is About Vitamin K-Induced Anaphylaxis
Vitamin K itself can cause fatal anaphylactoid reactions, particularly when given intravenously. This is a critical safety concern when reversing anticoagulation.
Incidence and Risk
- Anaphylactoid reactions occur in approximately 3 per 100,000 IV vitamin K doses via a non-IgE mechanism, possibly due to the polyoxyethylated castor oil solubilizer 3, 4
- These reactions can result in cardiac arrest, severe hypotension, bronchospasm, bradycardia/tachycardia, and dyspnea 3, 4
- Fatal reactions have been documented even with low doses (<5 mg) given by slow dilute infusion 5
- The FDA database contains 132 anaphylactoid reactions from IV vitamin K with 24 fatalities (18% case fatality rate) 5
Route-Specific Risk
- IV route carries the highest risk: 69% of IV vitamin K adverse reactions were anaphylactoid with 18% fatality rate 5
- Non-IV routes are safer: Only 18% of non-IV vitamin K reactions were anaphylactoid with 3% fatality rate 5
- Oral route is preferred for non-emergency reversal due to predictable effectiveness, convenience, and superior safety profile 3, 4
- Subcutaneous administration has unpredictable absorption and is not recommended 3
Anticoagulation Reversal in Patients Requiring Urgent Treatment
For patients on warfarin who develop life-threatening bleeding or require emergency surgery, use 4-factor prothrombin complex concentrate (PCC) 25-50 U/kg IV plus vitamin K 5-10 mg by slow IV infusion over 30 minutes. 3, 4
Dosing Algorithm Based on INR
- INR 2-4: PCC 25 U/kg 3, 4
- INR 4-6: PCC 35 U/kg 3, 4
- INR >6: PCC 50 U/kg 3, 4
- Maximum PCC dose is 5,000 units (capped at 100 kg body weight) 3
Critical Safety Measures for IV Vitamin K
Always administer IV vitamin K by slow infusion over 30 minutes, never as IV push, to minimize anaphylaxis risk. 3, 4
- Co-administer vitamin K with PCC because factor VII has only a 6-hour half-life, requiring vitamin K for sustained endogenous factor synthesis 3, 4
- Do not exceed 10 mg vitamin K in acute reversal, as higher doses create a prothrombotic state and prevent re-warfarinization for days 3, 4
- Have resuscitation equipment immediately available when administering IV vitamin K 6, 5
Alternative for Non-Life-Threatening Situations
For elevated INR without major bleeding, use oral vitamin K to avoid IV-associated anaphylaxis risk. 3, 4
- INR 5-9 without bleeding: Oral vitamin K 1-2.5 mg (only if high bleeding risk factors present) 3, 4
- INR >10 without bleeding: Oral vitamin K 5 mg 3, 4
- Oral administration achieves INR <4 within 24 hours in 85% of patients without the anaphylaxis risk of IV administration 3, 4
Key Clinical Pitfall
The most dangerous error is administering IV vitamin K too rapidly or without proper monitoring. Even slow infusion carries risk, and fatal anaphylaxis has occurred despite adherence to recommended administration techniques 6, 5. The oral route should be strongly preferred whenever the clinical situation permits a 24-hour timeframe for INR correction 3, 4.