Dextromethorphan and quinidine and Rifampin interaction
Dextromethorphan and quinidine and Rifampin: the Rifampin prescribing label flags this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
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
…exposure Progestins Anticonvulsants Phenytoin Administered with rifampin 450 mg daily Decrease exposure Antiarrhythmics Disopyramide 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…
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Open in the checkerNot 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.