Bismuth subcitrate, metronidazole, and tetracycline and Phenytoin interaction
Bismuth subcitrate, metronidazole, and tetracycline and Phenytoin: the Bismuth subcitrate, metronidazole, and tetracycline prescribing label describes 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 Bismuth subcitrate, metronidazole, and tetracycline (Bismuth Subcitrate Potassium, Metronidazole and Tetracycline Hydrochloride) label · effective 2026-04-13
Inducers of CYP450 liver enzymes The simultaneous administration of bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride and drugs that induce microsomal liver enzymes, such as phenytoin or phenobarbital, may accelerate the elimination of metronidazole, resulting in reduced plasma concentrations of metronidazole.
Monitor phenytoin concentrations during treatment with bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride.
Impaired clearance of phenytoin has also been reported in this situation.
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.