Vitamin K (Phytomenadione)
Brand names: Konakion MM Paediatric
Vitamin K (phytomenadione) is administered to newborn infants to prevent vitamin K deficiency bleeding (haemorrhagic disease of the newborn).
Adult dose
Paediatric dose
Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.
This per-kilogram figure is the label's own dose for PRETERM NEONATES OF LESS THAN 36 WEEKS GESTATION WEIGHING LESS THAN 2.5 kg: 0.4 mg/kg (equivalent to 0.04 ml/kg) intramuscularly or intravenously at birth or soon after birth, and the SPC states that this parenteral dose should not be exceeded. It is a single birth dose, not a daily total. Healthy neonates of 36 weeks gestation and older, preterm neonates weighing 2.5 kg or greater, and term neonates at special risk receive a fixed 1 mg parenteral dose instead, not this weight-based dose — see adultDose. SPC weight table for preterm babies at birth: 1 kg, 0.4 mg, 0.04 ml; 1.5 kg, 0.6 mg, 0.06 ml; 2 kg, 0.8 mg, 0.08 ml; 2.5 kg, 1 mg, 0.1 ml; over 2.5 kg, 1 mg, 0.1 ml. CAUTION FROM THE LABEL: care is required when calculating and measuring the dose in relation to the baby's weight — ten-times dosing errors are common; use 0.5 ml syringes with 0.01 ml graduations for volumes of 0.04 ml to 0.1 ml. Parenteral administration to premature babies weighing less than 2.5 kg may increase the risk of kernicterus (bilirubin encephalopathy). Verify against a children's formulary and local neonatal policy.
Contraindications
- Hypersensitivity to the active substance or to any of the excipients listed in section 6.1
Side effects
- Anaphylactoid reactions have been reported after intravenous injection of this medicine
- Local irritation may occur at the injection site, but is unlikely because of the small injection volume
- Rarely, injection site reactions may occur which may be severe, including inflammation, atrophy and necrosis
Monitoring
- Base the amount and frequency of any further doses on the neonate's coagulation status
- Parenteral administration to premature babies weighing less than 2.5 kg may increase the risk of kernicterus (bilirubin encephalopathy)
- Inspect the ampoule before use — the contents should be clear; if incorrect storage has made them turbid or caused phase separation, the ampoule must not be used
- When used as an antidote to coumarin anticoagulants: measure prothrombin time 2 to 6 hours after the dose and repeat administration if the response has not been adequate; frequent monitoring of vitamin K dependent clotting factors is essential in these patients
Clinical monograph
How it works
It is an essential cofactor for the hepatic gamma-carboxylation of clotting factors II, VII, IX and X (and proteins C and S), enabling synthesis of functional coagulation factors that newborns are otherwise deficient in.
Prescribing in practice
- Routine prophylaxis is recommended for all newborns because vitamin K deficiency bleeding, including late and intracranial bleeding, can be severe or fatal and is largely preventable.
- The intramuscular route gives reliable single-dose protection, whereas the oral route requires a multi-dose schedule and is less protective against late bleeding, particularly with exclusive breastfeeding or cholestasis.
- Administer according to the SPC and local neonatal policy, ensuring the correct neonatal preparation and route are used.
Monitoring
Routine laboratory monitoring is not required for prophylaxis; ensure any oral schedule is completed and remain alert to bleeding in infants with malabsorption or cholestasis.
Counselling the patient
- Explain that vitamin K is offered to all newborns to prevent a rare but serious bleeding problem.
- A single injection gives the most reliable protection; if the oral route is chosen, all the scheduled doses must be completed.
- Breastfed babies are at higher risk, so completing the recommended vitamin K is particularly important.
Evidence & guidelines
Routine neonatal vitamin K prophylaxis is long-established UK practice endorsed by national guidance, with intramuscular administration recognised as the most effective route for preventing vitamin K deficiency bleeding.
Reference: RCPCH/BAPM Vitamin K Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).
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Curated clinical cross-links plus same-class fallbacks.
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