What is the recommended dose of Vitamin K (Vitamin K) for adults and newborns?

Vitamin K Dosing Recommendations

Newborns (Term Infants)

All newborns should receive a single intramuscular dose of 0.5 to 1.0 mg vitamin K1 within one hour of birth, as this is the most effective route for preventing all forms of vitamin K deficiency bleeding. 1, 2

Intramuscular Administration (Preferred)

• Single IM dose of 0.5-1.0 mg at birth is the gold standard and most reliable method to prevent early, classic, and late vitamin K deficiency bleeding (VKDB) 1, 2, 3, 4
• Should be administered within one hour of birth 1, 2
• This route is preferred because it ensures complete absorption and compliance, eliminating the risk of regurgitation or missed doses 5, 3

Oral Administration (Alternative if Parents Decline IM)

If parents refuse intramuscular administration after adequate counseling about increased bleeding risk, use one of these oral regimens 5, 3, 4:

• Option 1: 2 mg at birth, 2 mg at 4-6 days, and 2 mg at 4-6 weeks 6, 5
• Option 2: 2 mg at birth, then weekly 1 mg doses for 3 months (12 weeks total) 6, 5, 7

Critical caveat: Oral prophylaxis is significantly less effective than IM administration for preventing late VKDB, and parents must be explicitly informed of this increased risk 8, 5, 3, 4. If the infant vomits or regurgitates within 1 hour of oral administration, the dose should be repeated 5.

Contraindications to Oral Route

Oral vitamin K should never be used in 5:

• Preterm infants
• Infants with cholestasis or impaired intestinal absorption
• Infants too unwell to take oral medication
• Infants whose mothers took medications interfering with vitamin K metabolism (anticonvulsants, anticoagulants, antituberculosis drugs)

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Preterm Infants

Preterm infants on parenteral nutrition require 10 μg/kg/day of vitamin K1. 6, 1, 9

• The first dose must be given IM or slow IV route, not orally 8
• Subsequent doses should be individualized based on clinical status and coagulation parameters 8
• These infants are at higher risk due to immature hepatic function and delayed enteral feeding 8

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High-Risk Newborns

For infants at elevated risk (premature, birth asphyxia, difficult delivery, maternal anticoagulant use, known hepatic disease), the initial dose must be given IM or slow IV 8:

• First dose: 1 mg IM or slow IV (not exceeding 1 mg per minute) 2, 8
• Higher doses may be necessary if mother received oral anticoagulants 2
• Repeat dosing based on clinical response and coagulation studies 8

Maternal Anticoagulant Use

• Mothers on vitamin K-inhibiting drugs should receive antenatal prophylaxis: 10-20 mg/day orally for 15-30 days before delivery to prevent early VKDB 8
• Newborns still require standard prophylaxis at birth 8

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Adults

For adults requiring vitamin K supplementation, the dose ranges from 2.5 to 10 mg for most indications, with higher doses (up to 25-50 mg) reserved for severe deficiency or anticoagulant reversal. 1, 2

Routine Supplementation

• General supplementation: 1-10 mg/day depending on age and risk factors 10
• Parenteral nutrition: 200 μg/day 1
• Daily administration is preferred over intermittent dosing due to low storage capacity 10

Anticoagulant Reversal

• Initial dose: 2.5-10 mg, up to 25 mg initially 2
• In rare instances, 50 mg may be required 2
• Maximum effect occurs within 6-12 hours for IV administration, 24 hours for oral 1
• If prothrombin time not corrected in 6-8 hours, repeat the dose 2
• Route: subcutaneous preferred; if IV unavoidable, inject slowly not exceeding 1 mg per minute 2

Hypoprothrombinemia from Other Causes

• Dose range: 2.5-25 mg, rarely up to 50 mg 2
• Amount and route depend on severity and response 2

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Special Populations

Cystic Fibrosis and Malabsorption

• Infants: 0.3-1.0 mg/day 10
• Older children and adults: 1-10 mg/day depending on age 10
• Higher doses for those on long-term antibiotics or with liver disease 10
• All exclusively breastfed CF infants require supplementation 10

Exclusively Breastfed Infants

• Breast milk contains inadequate vitamin K, making these infants particularly vulnerable 6, 8
• Must receive prophylaxis at birth and continued supplementation if oral route chosen 10, 6

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Administration Considerations

Route-Specific Guidelines

• IM/Subcutaneous: Preferred routes when possible 2
• IV: Only when unavoidable; inject very slowly (≤1 mg/minute) to avoid anaphylactoid reactions 2
• Oral: Less reliable due to variable absorption and compliance issues 5, 3

Dilution and Preparation

• May be diluted with preservative-free 0.9% sodium chloride, 5% dextrose, or 5% dextrose with sodium chloride 2
• Benzyl alcohol-containing diluents are contraindicated in newborns due to toxicity risk 2
• Administer immediately after dilution and discard unused portions 2
• Protect from light at all times 2

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Monitoring

Newborns

• Routine monitoring of vitamin K concentrations is not recommended 6
• Prothrombin time (PT) and partial thromboplastin time (PTT) can be used for indirect assessment in low-risk infants but lack specificity 6, 9
• PIVKA-II (undercarboxylated vitamin K-dependent proteins) is the preferred biomarker for at-risk patients when available 6, 9
• Prompt PT shortening within 2-4 hours after vitamin K administration is diagnostic of VKDB 6, 2

Adults

• Monitor coagulation parameters, especially in patients on anticoagulant therapy 1
• PIVKA-II and undercarboxylated osteocalcin can assess status but are not routinely used due to cost 10

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Safety

Vitamin K1 (phylloquinone) has no known adverse effects or toxicity concerns with supplementation. 10, 6

• The theoretical concern about childhood leukemia from IM administration has been definitively excluded for solid tumors, though a very low potential risk cannot be completely ruled out 8
• This minimal theoretical risk is vastly outweighed by the proven life-threatening consequences of VKDB 5, 3