Rifampicin and Warfarin: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Rifampicin and Warfarin unless specifically directed by your doctor.
How Rifampicin interacts with Warfarin
Rifampicin induces CYP2C9, CYP3A4, and CYP1A2, accelerating metabolism of both warfarin enantiomers and reducing anticoagulant effect, often requiring 2-3 fold dose increases.
What you should do
Increase INR monitoring weekly during rifampicin therapy and for 2-4 weeks after stopping; titrate warfarin dose accordingly.
Key facts
Severity
Major — avoid combination
Mechanism
Rifampicin induces CYP2C9, CYP3A4, and CYP1A2, accelerating metabolism of both warfarin enantiomers and reducing anticoa...
Action
Increase INR monitoring weekly during rifampicin therapy and for 2-4 weeks after stopping; titrate warfarin dose accordi...
Frequently asked questions
Can I take Rifampicin and Warfarin together?
No — this combination should generally be avoided. Increase INR monitoring weekly during rifampicin therapy and for 2-4 weeks after stopping; titrate warfarin dose accordingly.
What is the severity of this interaction?
The interaction between Rifampicin and Warfarin is classified as Major — avoid combination. Rifampicin induces CYP2C9, CYP3A4, and CYP1A2, accelerating metabolism of both warfarin enantiomers and reducing anticoagulant effect, often requiring 2-3 fold dose increases.
What should I do if I'm prescribed both?
Increase INR monitoring weekly during rifampicin therapy and for 2-4 weeks after stopping; titrate warfarin dose accordingly. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.