Drug & supplement interaction

Lactobacillus Johnsonii + Ondansetron

Ondansetron brand name: Zofran.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Lactobacillus Johnsonii and Ondansetron in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Lactobacillus Johnsonii and Ondansetron

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Ondansetron and Lactobacillus Johnsonii in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Lactobacillus Johnsonii safety at a glance

Lactobacillus John... overall Use caution Generally well tolerated in healthy adults, but people who are seriously ill or immune-compromised should be cautious.
Pregnancy Use caution There is not enough reliable safety data, so use only with a doctor's guidance.
Breastfeeding Use caution Safety has not been well studied, so check with a healthcare provider before using.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Ondansetron and Lactobacillus Johnsonii? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Ondansetron

Interactions in our licensed database are recorded against drug classes, not just single drug names. Ondansetron is filed under 7 classifications — including serotonergic drugs, serotonergic drugs, cytochrome p450 1a2 (cyp1a2) substrates. Lactobacillus Johnsonii has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Ondansetron’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Lactobacillus Johnsonii Does Interact With Other Medications

Lactobacillus Johnsonii has 182 moderate known drug interactions in our database — Ondansetron isn’t one of them. If you take anything else, check it against the full list below.

Moderate 182 No known interaction 2,648 (incl. Ondansetron)
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.

What to actually watch for

What Lactobacillus Johnsonii Itself Has Been Linked To

This is not an interaction — nothing below involves Ondansetron. It is the side-effect record for Lactobacillus Johnsonii on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Lactobacillus Johnsonii, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • A higher chance of infection Worth acting on Additional detail

    “Since Lactobacillus johnsonii preparations contain live and active microorganisms, there is some concern that they might cause pathogenic infection in some patients. Some lactobacilli species have been isolated in cases of bacteremia, sepsis, splenic abscess, endocarditis, necrotizing fasciitis, pancreatic necrosis, and meningoencephalitis.”

    Lactobacillus Johnsonii · Natural Medicines adverse-effect record, reported in sepsis.

    1 source cited
    1. 107543. Rossi F, Amadoro C, Gasperi M, Colavita G. Lactobacilli infection case reports in the last three years and safety implications. Nutrients. 2022;14(6):1178. PubMed

Everything above comes from the Natural Medicines adverse-effect record for Lactobacillus Johnsonii — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Ondansetron’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Ondansetron column appears here.

From our Q&A

Questions About Lactobacillus Johnsonii or Ondansetron

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Lactobacillus Johnsonii or Ondansetron, 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 Ondansetron

This page covers Lactobacillus Johnsonii only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ondansetron page lists 195 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), Lithium (major), St. John's Wort (major) and 1,3-dmaa (moderate).

By severity: 4 major · 145 moderate · 46 minor.

From our pharmacist’s overview on the Ondansetron page

“Ondansetron (Zofran) often stands between you and relentless nausea from chemotherapy or surgery, so read this page carefully. Four of the 195 ingredients rate major.”

Reviewed by 2 · Jul 18, 2026

Open the Ondansetron 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. Even though Lactobacillus Johnsonii itself has no known interaction with Ondansetron, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Lactobacillus Johnsonii and Ondansetron 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

#1,172 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ondansetron
Top half

#1,255 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Lactobacillus Johnsonii reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Lactobacillus Johnsonii and Ondansetron records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
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.

Lactobacillus johnsonii · Lactobacillaceae · Whole live bacteria (probiotic culture) · Capsules, tablets, powders, and fermented foods or dairy products containing the live culture

An interaction check asks whether these two react with each other — it does not ask whether Lactobacillus Johnsonii is a good idea for someone in your situation. Here is what our Lactobacillus Johnsonii record says about it on its own.

Lactobacillus Johnsonii: dosing

There is no official standardized dose for Lactobacillus johnsonii. Probiotic amounts are usually measured in colony-forming units (CFUs), and products vary widely.The best approach is to follow the directions on the product label and not exceed the recommended amount.

From our Lactobacillus Johnsonii monograph — the full record covers uses, side effects and every documented interaction.

Read the full Lactobacillus Johnsonii monograph & all interactions
Medication

About Ondansetron

What Is Ondansetron Used For?

Brand name: Zofran

Ondansetron is used to prevent nausea and vomiting in several situations. Oral forms (tablets, orally disintegrating tablets, and oral solution) are approved to prevent nausea and vomiting from highly or moderately emetogenic (nausea-causing) cancer chemotherapy, from radiation therapy to the abdomen or whole body, and from surgery.

Ondansetron injection (given intravenously or intramuscularly in a clinical setting) is approved to prevent nausea and vomiting from emetogenic cancer chemotherapy — including high-dose cisplatin — in adults and children as young as 6 months old, as well as to prevent postoperative nausea and vomiting.

Most-Reported Side Effects for Ondansetron

From FAERS, the FDA’s public side-effect reporting system (121,840 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Nausea 14,459 reports
Fatigue 10,275 reports
Diarrhea 9,488 reports
Vomiting 8,777 reports
Dyspnea 5,971 reports
See full Ondansetron 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
182Moderate
0Minor
2,647No known interaction
182 Moderate 2,647 No interaction
Moderate

182 interactions

Showing 60 of 182 moderate interactions — see all 182 on the Lactobacillus Johnsonii page.

No interaction 2,647 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 2,647 medications checked with no known interaction — see the full Lactobacillus Johnsonii list.

See the full Lactobacillus Johnsonii interactions page
See every supplement checked against Ondansetron, ranked by severity
Evidence & sources

Lactobacillus Johnsonii References

The 2 references that drive our Lactobacillus Johnsonii monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Pierce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: The Stonesong Press, 1999:19.
  2. Rossi F, Amadoro C, Gasperi M, Colavita G. Lactobacilli infection case reports in the last three years and safety implications. Nutrients. 2022;14(6):1178. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Lactobacillus Johnsonii and Ondansetron Together: Common Questions

Is it safe to take Lactobacillus Johnsonii with Ondansetron?
We do not list a known interaction between Lactobacillus Johnsonii and Ondansetron. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
How was the Lactobacillus Johnsonii and Ondansetron combination checked?
Interactions in our licensed database are recorded against drug classes. Ondansetron is filed under 7 classifications, and Lactobacillus Johnsonii has documented interactions with 1 drug class — none of Ondansetron's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Lactobacillus Johnsonii interact with any other medications?
Yes. Lactobacillus Johnsonii has 182 documented drug interactions in our database — Ondansetron is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Ondansetron interact with any supplements?
Yes. Ondansetron has documented interactions with 195 supplements in our database — Lactobacillus Johnsonii is not one of them. The Ondansetron interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Lactobacillus Johnsonii monograph Uses, safety profile, and every drug interaction in one place Ondansetron drug information The full plain-English guide to this medication Ondansetron supplement interactions Every supplement checked against Ondansetron, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Ondansetron and Lactobacillus Johnsonii?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.