Drug & supplement interaction

Lactobacillus Johnsonii + Natalizumab

Natalizumab brand name: Tysabri.

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 Natalizumab 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Lactobacillus Johnsonii and Natalizumab

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 Natalizumab 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 Natalizumab and Lactobacillus Johnsonii? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Natalizumab

Interactions in our licensed database are recorded against drug classes, not just single drug names. Natalizumab is filed under 2 classifications — immunosuppressants, oral drugs. Lactobacillus Johnsonii has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Natalizumab’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 — Natalizumab 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. Natalizumab)
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

No Interaction Found — But Data Suggests Lactobacillus Johnsonii and Natalizumab May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • A higher chance of infection Worth acting on Additional detail

    Lactobacillus Johnsonii

    “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

    Natalizumab

    Listed in the ADVERSE REACTIONS section of the FDA label for Natalizumab. Read the label on DailyMed ›

Effects for Natalizumab come from the ADVERSE REACTIONS section of its FDA label; effects for Lactobacillus Johnsonii come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 180,844 voluntary FDA FAERS reports for Natalizumab that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Natalizumab Is Prescribed For, and What Lactobacillus Johnsonii Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Natalizumab is a prescription medicine with approved uses on its FDA label. Lactobacillus Johnsonii is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Natalizumab is prescribed for: Tysabri is approved for adults with relapsing forms of multiple sclerosis — including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease. It is used as a solo therapy (monotherapy) for MS, not combined with other disease-modifying drugs. Tysabri is also approved to induce and maintain remission in adults with moderately to severely active Crohn's disease when standard treatments and TNF-alpha inhibitors have not worked or cannot be tolerated. In Crohn's disease, it must not be combined with immunosuppressants or TNF-alpha inhibitors.

Lactobacillus Johnsonii has been studied for:

  • Diarrhea studied, not established Lactobacillus Johnsonii has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Lactobacillus Johnsonii for diarrhea

    Although there has been interest in using oral Lactobacillus johnsonii for diarrhea prevention, there is insufficient reliable information about the clinical effects of L. johnsonii for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Natalizumab on your own; if you are taking Lactobacillus Johnsonii for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Natalizumab

This page covers Lactobacillus Johnsonii only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Natalizumab page lists 70 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Active Hexose Correlated Compound (ahcc) (moderate), Alfalfa (moderate), American Ginseng (moderate) and Andrographis (moderate).

By severity: 1 major · 59 moderate · 10 minor.

From our pharmacist’s overview on the Natalizumab page

“Natalizumab (Tysabri) works by quieting an overactive immune system in multiple sclerosis and Crohn's disease, and that is exactly why this list of 70 supplements deserves real care rather than a shrug. Fifty-three of them, ashwagandha among the familiar names, are believed to stimulate immune function, which could work directly agains…”

Reviewed by 2 · Jul 18, 2026

Open the Natalizumab 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 Natalizumab, 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 Natalizumab 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

#1,171 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Natalizumab
Steady interest

#1,778 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 Natalizumab 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 Natalizumab Injection

What Is Natalizumab Injection Used For?

Brand name: Tysabri

Tysabri is approved for adults with relapsing forms of multiple sclerosis — including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease. It is used as a solo therapy (monotherapy) for MS, not combined with other disease-modifying drugs.

Tysabri is also approved to induce and maintain remission in adults with moderately to severely active Crohn's disease when standard treatments and TNF-alpha inhibitors have not worked or cannot be tolerated. In Crohn's disease, it must not be combined with immunosuppressants or TNF-alpha inhibitors.

Most-Reported Side Effects for Natalizumab

From FAERS, the FDA’s public side-effect reporting system (180,844 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 19,621 reports
Multiple sclerosis relapse 16,915 reports
Headache 9,996 reports
Multiple sclerosis 9,785 reports
Gait disturbance 9,501 reports
See full Natalizumab 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
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 Natalizumab, 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 Natalizumab Together: Common Questions

Is it safe to take Lactobacillus Johnsonii with Natalizumab?
We do not list a known interaction between Lactobacillus Johnsonii and Natalizumab. 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.
Do Lactobacillus Johnsonii and Natalizumab have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Lactobacillus Johnsonii and Natalizumab used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Lactobacillus Johnsonii in each. That is a conversation for your prescriber, especially if Natalizumab is being adjusted to a target.
How was the Lactobacillus Johnsonii and Natalizumab combination checked?
Interactions in our licensed database are recorded against drug classes. Natalizumab is filed under 2 classifications, and Lactobacillus Johnsonii has documented interactions with 1 drug class — none of Natalizumab'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 — Natalizumab 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 Natalizumab interact with any supplements?
Yes. Natalizumab has documented interactions with 70 supplements in our database — Lactobacillus Johnsonii is not one of them. The Natalizumab 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 Natalizumab Injection drug information The full plain-English guide to this medication Natalizumab supplement interactions Every supplement checked against Natalizumab, 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 Natalizumab 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.