Is cranberry juice / cranberry supplements Safe with warfarin?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Limit cranberry juice to normal dietary amounts (less than 240 mL/day). Avoid cranberry juice concentrates or high-dose cranberry supplements (approaching 1–2 L/day or equivalent) while on warfarin. Have your INR checked if you regularly consume cranberry products.
Why this interaction occurs
Cranberry juice inhibits CYP enzymes (CYP3A and CYP2C9) in vitro, and large quantities consumed over extended periods (>3–4 weeks) may alter warfarin's pharmacodynamic effect, potentially increasing bleeding risk. Routine dietary amounts appear safe, but concentrated or excessive intake poses a measurable risk.
Evidence
Evidence level: moderate.
Data source
PubMed - PMID 23958198
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 cranberry juice / cranberry supplements interactions → · All warfarin interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.