Is St. John's Wort Safe with Acenocoumarol?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Avoid combining St. John's Wort with Acenocoumarol — St. John's Wort speeds up the liver enzyme (CYP2C9) that breaks down Acenocoumarol, potentially reducing its effectiveness. Consult your doctor.
Why this interaction occurs
PXR activation increases CYP2C9 expression. Result: decreased drug levels.
Evidence
Evidence level: strong.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 4,114 reports mentioning Acenocoumarol. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Acenocoumarol + 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 St. John's Wort interactions → · All Acenocoumarol interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.