Is Cigarette Smoking (Tobacco) Safe with warfarin?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Inform your doctor if you start or stop smoking. Changes in smoking habits can significantly alter warfarin levels and require INR monitoring and possible dose adjustment.
Why this interaction occurs
Cigarette smoking is listed as a CYP1A2 inducer in the FDA label. Induction of CYP1A2 increases metabolism of the R-enantiomer of warfarin, potentially decreasing INR and reducing anticoagulant effectiveness.
Evidence
Evidence level: strong.
Data source
FDA Drug Label (OpenFDA)
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 Cigarette Smoking (Tobacco) interactions → · All warfarin interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.