Rifampicin is one of the most potent enzyme inducers in clinical use. It strongly induces CYP3A4 and several other enzymes and transporters, and can lower levels of many drugs to the point of failure.
Common casualties include hormonal contraceptives, warfarin and the direct oral anticoagulants, many antiretrovirals, tacrolimus and ciclosporin, azole antifungals, some statins, methadone, and corticosteroids. Induction builds over about a week and takes around two weeks to wear off after stopping, so interacting doses need review both when rifampicin starts and when it ends.
Rifabutin is a weaker inducer and is sometimes substituted when an interaction cannot be managed.
- Check every co-prescribed drug against an interaction resource before starting rifampicin
- Advise non-hormonal or injectable contraception during rifampicin treatment and for a month after
- Avoid direct oral anticoagulants with rifampicin; manage warfarin with close INR monitoring
- Review doses again about two weeks after rifampicin stops
Why it matters
Rifampicin's interactions cause treatment failures across specialties, often weeks after it is started.
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