Bismuth subcitrate, metronidazole, and tetracycline and Doxycycline interaction
Bismuth subcitrate, metronidazole, and tetracycline and Doxycycline: both prescribing labels flag 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 Doxycycline (Doxycycline Hyclate) label · effective 2026-06-30
Doxycycline hyclate are contraindicated in persons who have shown hypersensitivity to any of the tetracyclines.
Avoid co-administration of tetracyclines with penicillin.
Penicillin Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines, including doxycycline hyclate in conjunction with penicillin.
A decrease in fibula growth rate has been observed in premature infants given oral tetracycline in doses of 25 mg/kg every 6 hours.
Women of childbearing age who are overweight or have a history of IH are at greater risk for developing tetracycline associated IH.
From the Bismuth subcitrate, metronidazole, and tetracycline (Bismuth Subcitrate Potassium, Metronidazole and Tetracycline Hydrochloride) label · effective 2026-04-13
As with other antibacterial drugs, use of tetracycline hydrochloride may result in overgrowth of nonsusceptible organisms, including fungi.
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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.