Is Vitamin K Safe with Warfarin?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Maintain a consistent daily intake of dietary vitamin K rather than avoiding it entirely. Consider daily low-dose oral vitamin K supplementation to stabilize INR if dietary intake is highly variable. Monitor INR closely whenever vitamin K intake changes significantly.
Why this interaction occurs
Warfarin acts as a vitamin K antagonist; fluctuations in vitamin K intake directly alter INR control, increasing risk of bleeding (subtherapeutic) or thromboembolism (supratherapeutic). Stable vitamin K intake improves anticoagulation stability.
Evidence
Evidence level: strong.
Data source
PubMed - PMID 28635328
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 134,328 reports mentioning Warfarin. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Warfarin + 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 interactions → · All Warfarin interactions →
Already checked this one — check your whole list
Educational only — not medical advice.
Always confirm with your doctor or pharmacist.