Drug & supplement interaction

Kratom + Metronidazole, Tetracyline, Bismuth Subcitrate Potassium

Metronidazole, Tetracyline, Bismuth Subcitrate Potassium brand name: Pylera.

Moderate Interaction
Medically reviewed by · Updated October 2026
The bottom line Moderate

Kratom has a moderate interaction with Metronidazole, Tetracyline, Bismuth Subcitrate Potassium. CYP3A4 inhibitors might increase the concentrations and clinical effects of kratom's primary active alkaloid mitragynine.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Kratom and Metronidazole, Tetracyline, Bismuth Subcitrate Potassium

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INHIBITORS

Why this applies to Metronidazole, Tetracyline, Bismuth Subcitrate Potassium

Metronidazole, Tetracyline, Bismuth Subcitrate Potassium falls under CYTOCHROME P450 3A4 (CYP3A4) INHIBITORS — the group Kratom interacts with.

CYP3A4 inhibitors might increase the concentrations and clinical effects of kratom's primary active alkaloid mitragynine.
A pharmacokinetic study in healthy adults suggests that CYP3A4 inhibition with itraconazole increases the peak plasma concentration (Cmax) of mitragynine by about 1.5-fold. However, CYP3A4 inhibition reduces the Cmax and area under the plasma concentration time curve (AUC) over 72 hours of 7-hydroxymitragynine, one of kratom's active constituents, by about 3-fold, possibly by decreasing the metabolism of mitragynine to 7-hydroxymitragynin.
Animal research suggests that CYP3A4 inhibition with ketoconazole reduces the metabolism and clearance of kratom, increasing the Cmax of the active metabolite mitragynine by 130%, time to reach maximum plasma concentration (Tmax) from 1 to 2.6 hours, and AUC by 120%. Additionally, CYP3A4-mediated conversion of mitragynine into 7-hydroxymitragynine increases systematic exposure by 130%. However, other CYP isoforms are likely involved in this conversion. CYP3A4 inhibition could lead to increased adverse effects and mu-opioid-receptor-mediated behavioral effects associated with kratom and its metabolites.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing about Pylera (the combo of bismuth, metronidazole, and tetracycline): the part that matters here is the metronidazole. Metronidazole can mildly slow down CYP3A4, an enzyme your body uses to process kratom. When that enzyme is blocked, the main kratom compound (mitragynine) can build up a bit higher in your blood, which may make kratom's opioid-like effects and side effects feel stronger. Think more drowsiness, dizziness, nausea, constipation, or slowed breathing.

On top of that, metronidazole comes with its own warning: mixing it with anything that affects the brain can add to grogginess, and metronidazole itself can cause real nausea. I'd hold off on kratom and talk with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kamble SH, Obeng S, León F, et al. Pharmacokinetic and Pharmacodynamic Consequences of Cytochrome P450 3A Inhibition on Mitragynine Metabolism in Rats. J Pharmacol Exp Ther 2023;385(3):180-192. PubMed
  2. Mongar P, Jaisi A, Inkviya T, Wungsintaweekul J, Wiwattanawongsa K. Effects of Itraconazole on Pharmacokinetics of Mitragynine and 7-Hydroxymitragynine in Healthy Volunteers. ACS Pharmacol Transl Sci 2024;7(3):823-833. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Kratom Also Interacts With Other Medications

Kratom has 983 moderate, 12 minor known drug interactions in our database — the Metronidazole, Tetracyline, Bismuth Subcitrate Potassium one above is one of them. If you take anything else, check it against the full list below.

Moderate 983 Minor 12 No known interaction 1,835 (incl. Metronidazole, Tetracyline, Bismuth Subcitrate Potassium)
Taking anything else?

Check Another of Your Medications Against Kratom

Covers the 2,830 medications we’ve checked against Kratom. Pick one to open its full report.

From our Q&A

Questions About Kratom or Metronidazole, Tetracyline, Bismuth Subcitrate Potassium

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Kratom or Metronidazole, Tetracyline, Bismuth Subcitrate Potassium, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Metronidazole, Tetracyline, Bismuth Subcitrate Potassium

This page covers Kratom only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metronidazole, Tetracyline, Bismuth Subcitrate Potassium page lists 148 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Oleander (major) and Siberian Cocklebur (major).

By severity: 6 major · 128 moderate · 14 minor.

From our pharmacist’s overview on the Metronidazole, Tetracyline, Bismuth Subcitrate Potassium page

“Alcohol is the risk to handle first with Pylera (metronidazole, tetracycline, and bismuth subcitrate potassium, usually prescribed for H. pylori stomach infections).”

Reviewed by 2 · Jul 18, 2026

Open the Metronidazole, Tetracyline, Bismuth Subcitrate Potassium interaction page

One more smart check

Taking Kratom as Part of a Dietary Supplement Product? Check It for Interactions

We hold 8 real supplement products containing Kratom, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Kratom. Your product may carry other ingredients that interact with Metronidazole, Tetracyline, Bismuth Subcitrate Potassium too, on top of Kratom — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Kratom and Metronidazole, Tetracyline, Bismuth Subcitrate Potassium Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Kratom
Top 25%

#332 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Metronidazole, Tetracyline, Bismuth Subcitrate Potassium
Top 25%

#537 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Kratom

What is Kratom?

Kratom
  • Pain relief
  • Opioid withdrawal symptoms
  • Anxiety and stress
  • Low energy or fatigue
  • Mood enhancement

Kratom is a Southeast Asian plant whose leaves act on the brain's opioid receptors and can produce both stimulant-like and opioid-like effects. It is not approved or proven safe by health regulators, carries real risks of dependence and serious harm, and its legal status varies widely. Talk to a pharmacist or doctor before considering it.

Read the full Kratom monograph & all interactions
Medication

About Bismuth, Metronidazole, and Tetracycline

What Is Bismuth, Metronidazole, and Tetracycline Used For?

Brand name: Pylera

This combination capsule treats Helicobacter pylori (H. pylori) infection in people who have a duodenal ulcer (an ulcer in the first part of the small intestine) or have had one within the past 5 years. It is always used together with omeprazole.

Clearing H. pylori has been shown to lower the chance that a duodenal ulcer comes back. The same use is listed for the generic bismuth subcitrate potassium, metronidazole and tetracycline hydrochloride capsules and for Pylera. It should only be used for infections proven or strongly suspected to be caused by bacteria.

See full Bismuth, Metronidazole, and Tetracycline drug information
Keep checking

Other Drugs & Kratom

Browse every other medication we’ve checked against Kratom — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
983Moderate
12Minor
1,834No known interaction
983 Moderate 12 Minor 1,834 No interaction
Moderate

983 interactions

Showing 60 of 983 moderate interactions — see all 983 on the Kratom page.

Minor

12 interactions

No interaction 1,834 drugs checked — show the list

We also checked Kratom against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,834 medications checked with no known interaction — see the full Kratom list.

See the full Kratom interactions page
See every supplement checked against Metronidazole, Tetracyline, Bismuth Subcitrate Potassium, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Kratom monograph › Uses, safety, and every drug interaction in one place Metronidazole, Tetracyline, Bismuth Subcitrate Potassium supplement interactions › Every supplement checked against Metronidazole, Tetracyline, Bismuth Subcitrate Potassium, ranked by severity Bismuth, Metronidazole, and Tetracycline drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Kratom and Metronidazole, Tetracyline, Bismuth Subcitrate Potassium Together: Common Questions

Can you take Kratom with Metronidazole, Tetracyline, Bismuth Subcitrate Potassium?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Kratom and Metronidazole, Tetracyline, Bismuth Subcitrate Potassium interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Metronidazole, Tetracyline, Bismuth Subcitrate Potassium and Kratom?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.