About vitamin k
Vitamin K1 (phytonadione)
Used for
- Treats or prevents bleeding caused by vitamin K deficiency
- Reverses certain effects of warfarin and related anticoagulants
Usual adult dose
For deficiency, commonly 2.5–25 mg by mouth, adjusted to cause and response. Warfarin reversal doses vary by bleeding severity and INR.
Usual dose in children
For deficiency, doses are weight-based and depend on age and cause; specialist guidance is required.
Common side effects
- Uncommon: nausea, vomiting, or abdominal discomfort
- Allergic reactions are rare with oral doses
Important warnings
- Not appropriate for every cause of bleeding
- May reduce warfarin’s anticoagulant effect and raise clot risk
- Dose depends on the cause and blood-test results
Pregnancy
Use when needed under medical supervision; vitamin K crosses the placenta.
Breastfeeding
Vitamin K passes into breast milk in small amounts; usual doses are generally compatible.
Interactions
- Warfarin and related vitamin K antagonists: can reduce anticoagulant effects
- Some antibiotics and bile-acid medicines may affect vitamin K status or absorption
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.