Rifampin and Toremifene interaction

Rifampin and Toremifene: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.

Major

Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.

What the FDA labels say

From the Rifampin label · effective 2026-05-05

Major

…Decrease exposure Mexiletine Decrease exposure Quinidine Decrease exposure Propafenone Decrease AUC by 50%-67% Tocainide Decrease exposure Antiestrogens Tamoxifen Decrease AUC by 86% Toremifene Decrease steady state concentrations of toremifene in serum Antithrombotic Agents Clopidogrel Prevention or Management: Concomitant use of clopidogrel and rifampin should…

Drug interactionsnames ToremifeneView label on DailyMed

From the Toremifene (Fareston) label · effective 2024-11-13

Major

Coadministration with a strong CYP3A4 inducer may result in a relevant decrease in FARESTON exposure and should be avoided.

Drug interactionsby drug classView label on DailyMed
Minor

Effect of Strong CYP3A4 Inducers on Toremifene Strong CYP3A4 enzyme inducers, such as dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, phenobarbital, St.

Drug interactionsby drug classView label on DailyMed

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Not medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.