Herb & supplement monograph

Lactobacillus Johnsonii Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Lactobacillus Johnsonii interacts with medications. The heart of this page is the interaction list — every drug Lactobacillus Johnsonii is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Lactobacillus Johnsonii is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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On this page

Interaction report

Drugs that interact with Lactobacillus Johnsonii

182 medications have a known interaction with Lactobacillus Johnsonii, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Lactobacillus Johnsonii using our pharmacist-reviewed interaction data.

AI summaries are generated from our Lactobacillus Johnsonii interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Lactobacillus Johnsonii combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Lactobacillus Johnsonii affects

Every type of medication (drug category) Lactobacillus Johnsonii is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 1 drug category Lactobacillus Johnsonii interacts with

Antibiotic Drugs

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.

Likelihood Probable Evidence D

Monograph

Lactobacillus Johnsonii: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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.

Scientific name: Lactobacillus johnsonii
Family: Lactobacillaceae
Part used: Whole live bacteria (probiotic culture)
Common forms: Capsules, tablets, powders, and fermented foods or dairy products containing the live culture

People commonly use it for

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

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated in healthy adults, but people who are seriously ill or immune-compromised should be cautious.

PregnancyInsufficient reliable information

There is insufficient reliable information available about the safety of Lactobacillus johnsonii during pregnancy and lactation. However, there are cu...

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

There is insufficient reliable information available about the safety of Lactobacillus johnsonii during pregnancy and lactation. However, there are cu...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Lactobacillus johnsonii is a type of friendly bacteria, or probiotic, that lives naturally in the human digestive tract. It also appears in some fermented foods and dairy products and is added to certain supplements.

Like other Lactobacillus species, it is a lactic acid bacterium, which means it makes lactic acid as it breaks down sugars. This is part of how it may help shape the environment in the gut. Some strains, such as one labeled La1 or NCC 533, have been studied in research and used in commercial products.

People take L. johnsonii hoping to support digestion, balance their gut bacteria, and help their immune system. It is most often sold as a capsule, powder, or as part of a multi-strain probiotic blend.

How it works

As a probiotic, Lactobacillus johnsonii is thought to work in several ways, though much of this comes from laboratory and animal research.

It produces lactic acid and other compounds that may make the gut less friendly to harmful bacteria. It may also compete with unwanted microbes for space and nutrients, and help support the lining of the gut wall.

Some research suggests it may interact with the immune cells in the gut, which is why it is studied for immune support. These are proposed mechanisms, and more human research is needed to know how meaningful they are in everyday use.

Effectiveness

Does Lactobacillus Johnsonii work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 7 uses evaluated

1 Leans ineffective 6 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Ineffective Crohn disease