Drug & supplement interaction

Lactobacillus Johnsonii + Tobramycin

Tobramycin brand names: Nebcin, Tobi Podhaler, Bethkis, Kitabis PAK.

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

Lactobacillus Johnsonii has a moderate interaction with Tobramycin. Theoretically, taking Lactobacillus johnsonii with antibiotic drugs might decrease the effectiveness of L.

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

Lactobacillus Johnsonii and Tobramycin

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

Moderate

ANTIBIOTIC DRUGS

Why this applies to Tobramycin

Tobramycin falls under ANTIBIOTIC DRUGS — the group Lactobacillus Johnsonii interacts with.

Theoretically, taking Lactobacillus johnsonii with antibiotic drugs might decrease the effectiveness of L. johnsonii.
Lactobacillus johnsonii preparations usually contain live and active organisms. Therefore, simultaneously taking antibiotics might kill a significant number of the organisms. Tell patients to separate administration of antibiotics and L. johnsonii preparations by at least two hours.
Severity Moderate Likelihood Probable Evidence D

Interaction 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..

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

Here's the simple version: this interaction works the other way around from what most people worry about. Tobramycin won't be weakened by the probiotic. Instead, the antibiotic can harm the probiotic. Lactobacillus johnsonii is made of live, friendly bacteria, and tobramycin is designed to kill bacteria. If they cross paths at the same time, the antibiotic may wipe out a good chunk of those organisms before they can do their job.

Keep in mind this concern is mostly theoretical, based on how these two work rather than strong human studies. Your tobramycin will still fight your infection as expected. If you want the probiotic to have a fair shot, a common tip is to space the two apart. Check with your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pierce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: The Stonesong Press, 1999:19.

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

Lactobacillus Johnsonii Also Interacts With Other Medications

Lactobacillus Johnsonii has 181 moderate known drug interactions in our database — the Tobramycin one above is one of them. If you take anything else, check it against the full list below.

Moderate 181 No known interaction 2,649 (incl. Tobramycin)
Taking anything else?

Check Another of Your Medications Against Lactobacillus Johnsonii

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

Everything else you take

See Every Supplement That Interacts With Tobramycin

This page covers Lactobacillus Johnsonii only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tobramycin page lists 52 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Siberian Cocklebur (major), Aristolochia (moderate) and Bacillus Coagulans (moderate).

By severity: 3 major · 38 moderate · 11 minor.

From our pharmacist’s overview on the Tobramycin page

“Kidney protection is the first thing to understand with tobramycin (Nebcin, Tobi Podhaler, Bethkis, Kitabis PAK), an aminoglycoside antibiotic that can stress the kidneys even on its own, so this list warrants genuine care rather than a quick glance. The worst pairings, Siberian cocklebur and asarabacca, can injure the kidneys themselv…”

Reviewed by 2 · Jul 18, 2026

Open the Tobramycin interaction page

One more smart check

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

We hold 17 real supplement products containing Lactobacillus Johnsonii, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lactobacillus Johnsonii. Your product may carry other ingredients that interact with Tobramycin too, on top of Lactobacillus Johnsonii — 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 Lactobacillus Johnsonii and Tobramycin 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 Lactobacillus Johnsonii
Steady interest

#1,365 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Tobramycin
Steady interest

#2,651 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 Lactobacillus Johnsonii

What is Lactobacillus Johnsonii?

  • Digestive and gut health
  • Supporting healthy gut bacteria
  • Diarrhea prevention or relief
  • Immune support
  • Helping with stomach (H. pylori) discomfort

Lactobacillus johnsonii is a probiotic bacterium found naturally in the human gut and in some fermented foods, and it is used mainly for digestive and immune support. Human evidence for most specific health claims is still limited, so its benefits are uncertain. It is generally well tolerated in healthy people, but anyone with a weakened immune system, serious illness, or who is pregnant should talk to a pharmacist or doctor first.

Read the full Lactobacillus Johnsonii monograph & all interactions
Medication

About Tobramycin Injection

What Is Tobramycin Injection Used For?

Brand names: Nebcin, Tobi Podhaler, Bethkis, Kitabis PAK

Tobramycin Injection is used to treat serious and life-threatening bacterial infections caused by susceptible bacteria. It is approved for adults and children for infections of the blood (septicemia), lungs and airways, brain and spinal cord (meningitis), abdomen, skin, bones, and urinary tract.

Because antibiotic resistance is a growing concern, Tobramycin Injection should only be used when there is a proven or strongly suspected bacterial infection. Your care team will use culture and lab results to confirm it is the right choice.

See full Tobramycin Injection drug information
Keep checking

Other Drugs & Lactobacillus Johnsonii

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

0Major
181Moderate
0Minor
2,648No known interaction
181 Moderate 2,648 No interaction
Moderate

181 interactions

Showing 60 of 181 moderate interactions — see all 181 on the Lactobacillus Johnsonii page.

No interaction 2,648 drugs checked — show the list

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

Showing the 60 most looked-up of 2,648 medications checked with no known interaction — see the full Lactobacillus Johnsonii list.

See the full Lactobacillus Johnsonii interactions page
See every supplement checked against Tobramycin, 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
Lactobacillus Johnsonii monograph › Uses, safety, and every drug interaction in one place Tobramycin supplement interactions › Every supplement checked against Tobramycin, ranked by severity Tobramycin Injection 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 Lactobacillus Johnsonii and Tobramycin Together: Common Questions

Can you take Lactobacillus Johnsonii with Tobramycin?
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 Lactobacillus Johnsonii and Tobramycin 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 Tobramycin and Lactobacillus Johnsonii?

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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.