Isoniazid and Ketoconazole interaction
Isoniazid and Ketoconazole: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Isoniazid label · effective 2026-04-27
When ketoconazole is given in combination with isoniazid and rifampin the AUC of ketoconazole is decreased by as much as 88% after 5 months of concurrent isoniazid and rifampin therapy 4 .
Ketoconazole Potential interaction of ketoconazole and isoniazid may exist.
From the Ketoconazole label · effective 2026-07-07
Examples include: Antibacterials: isoniazid, rifabutin (see also under 'Drugs that may have their plasma concentrations increased'), rifampicin.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
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.