Is Vitamin K (dietary) Safe with warfarin sodium?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Eat a normal, balanced diet maintaining a consistent amount of vitamin K. Avoid drastic changes in dietary habits, such as eating large amounts of green leafy vegetables.
Why this interaction occurs
Vitamin K is a direct pharmacodynamic antagonist of warfarin. Changes in dietary vitamin K intake, particularly large increases from green leafy vegetables, can significantly reduce warfarin's anticoagulant effect and alter INR.
Evidence
Evidence level: strong.
Data source
FDA Drug Label
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 3,390,437 reports mentioning warfarin sodium. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the warfarin sodium + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Vitamin K (dietary) interactions → · All warfarin sodium interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.