Drug Interaction Report

Minocycline and Bismuth Subsalicylate: Interaction Details

A pharmacist-reviewed analysis of the Minocycline and Bismuth Subsalicylate interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Bismuth Subsalicylate

Bismarex Bismusal Bismusal® Estomaquil Kaopectate Reformulated Aug 2006 Kaopectate® Peptic Relief® Pepto-bismol
+

Minocycline

Amzeeq Arestin Cleeravue-M Dynacin® Emrosi Minocin Minocin® Minolira
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 112 documented Minocycline interactions, 23 are rated moderate — including this one.
Onset
delayed
Evidence
theoretical
Severity
Moderate

What happens

Decreased minocycline effectiveness

Interaction Deep Dive

The concurrent use of a tetracycline and bismuth subsalicylate may result in a 30% to 50% reduction in the absorption of the tetracycline12.

Why it happens (mechanism)

Decreased tetracycline absorption

Literature reports

1 report — tap to read

a) A study was conducted to evaluate the effect of bismuth subsalicylate on the absorption of doxycycline. Six patients received the following regimens with a two-week washout period separating each course: doxycycline 200 mg with or without bismuth subsalicylate 60 mL; bismuth subsalicylate administered 2 hours before or 2 hours after doxycycline 200 mg; multi-dose regimen of bismuth subsalicylate every 6 hours for 5 doses followed immediately by one dose of doxycycline 200 mg. Bismuth subsalicylate 60 mL significantly reduced peak serum concentrations of doxycycline when administered simultaneously, 2 hours before doxycycline, and with the multi-dose regimen. The bioavailability of doxycycline measured by area under the curve was similarly reduced 37% and 51%, respectively, with the concomitant administration of both preparations and the multi-dose regimen of bismuth subsalicylate 1.

Common questions

Can I take Minocycline and Bismuth Subsalicylate together?

Decreased minocycline effectiveness Always confirm with your pharmacist or prescriber before making any change.

How serious is the Minocycline and Bismuth Subsalicylate interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

How quickly could this interaction happen?

The documented onset is "delayed". Effects tend to build up gradually over days to weeks.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

  • Does my dose of Minocycline or Bismuth Subsalicylate need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there anything you'd monitor while I'm on both?

References (2)

  1. Ericsson CD, Feldman S, Pickering LK, et al: Influence of subsalicylate bismuth on absorption of doxycycline. JAMA 1982; 247:2266-2267. DOI
  2. Albert KS, Welch RD, DeSante KA, et al: Decreased tetracycline bioavailability caused by a bismuth subsalicylate antidiarrheal mixture. J Pharm Sci 1979; 68:586-588. PubMed
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Bismuth Subsalicylate

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All Bismuth Subsalicylate interactions (24) Bismuth Subsalicylate drug information
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Minocycline

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All Minocycline interactions (112) Minocycline drug information
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Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Minocycline + Activated Charcoal Asarabacca Beer Danshen Oleander Piracetam Siberian Cocklebur St. John's Wort + 323 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.