Bismuth subcitrate, metronidazole, and tetracycline and Lithium interaction
Bismuth subcitrate, metronidazole, and tetracycline and Lithium: 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 Bismuth subcitrate, metronidazole, and tetracycline (Bismuth Subcitrate Potassium, Metronidazole and Tetracycline Hydrochloride) label · effective 2026-04-13
Lithium In patients stabilized on relatively high doses of lithium, short-term use of bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride may cause elevation of serum lithium concentrations and signs of lithium toxicity due to the interaction between metronidazole and lithium.
Monitor serum lithium and serum creatinine concentrations daily for several days after beginning treatment with bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride to detect any increase that may precede clinical symptoms of lithium toxicity [see Drug Interactions ( 7.5 )] .
Lithium: Increased lithium serum concentrations; measure serum lithium and serum creatinine concentrations during therapy.
Serum lithium and serum creatinine concentrations should be monitored several days after beginning treatment with bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride to detect any increase that may precede clinical symptoms of lithium toxicity [see Warnings and Precautions ( 5.14 )] .
From the Lithium (Lithium Carbonate) label · effective 2026-08-16
• Diuretics, NSAID, renin-angiotensin system antagonists, or metronidazole may increase lithium serum concentrations.
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.