Drug & supplement interaction

Lactobacillus Delbrueckii + Methenamine Mandelate

Methenamine Mandelate brand names: Mandelamine, Methimazole.

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

Lactobacillus Delbrueckii has a moderate interaction with Methenamine Mandelate. Theoretically, taking Lactobacillus delbrueckii 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 Delbrueckii and Methenamine Mandelate

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

Moderate

ANTIBIOTIC DRUGS

Why this applies to Methenamine Mandelate

Methenamine Mandelate falls under ANTIBIOTIC DRUGS — the group Lactobacillus Delbrueckii interacts with.

Theoretically, taking Lactobacillus delbrueckii with antibiotic drugs might decrease the effectiveness of L. delbrueckii.
Lactobacillus delbrueckii 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. delbrueckii 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: methenamine mandelate works as a urinary antiseptic. In acidic urine it releases formaldehyde, which kills bacteria in the bladder and urinary tract. Because it can act like an antibacterial agent, taking it at the same time as your Lactobacillus delbrueckii probiotic could kill off some of those live, friendly bacteria before they ever get to work.

This doesn't hurt you, and it doesn't make the methenamine less effective. It just means you may not get the full benefit of the probiotic. The easy fix is timing: take your probiotic and your methenamine at least two hours apart. This concern is theoretical, based on how these products work, so don't stop either one. Your pharmacist can help you set up a simple schedule.

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 Delbrueckii Also Interacts With Other Medications

Lactobacillus Delbrueckii has 181 moderate known drug interactions in our database — the Methenamine Mandelate 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. Methenamine Mandelate)
Taking anything else?

Check Another of Your Medications Against Lactobacillus Delbrueckii

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

Everything else you take

See Every Supplement That Interacts With Methenamine Mandelate

This page covers Lactobacillus Delbrueckii only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methenamine Mandelate page lists 91 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Ascophyllum Nodosum (moderate).

By severity: 4 major · 77 moderate · 10 minor.

From our pharmacist’s overview on the Methenamine Mandelate page

“People take methenamine mandelate (Mandelamine) day after day to keep urinary tract infections at bay, and that long habit is exactly why the 91 supplements on this page deserve genuine vigilance. Four carry a major rating, and most of those point at the liver: Siberian cocklebur has been linked to outright liver failure, and heavy bee…”

Reviewed by 2 · Jul 18, 2026

Open the Methenamine Mandelate interaction page

One more smart check

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

We hold 1,200 real supplement products containing Lactobacillus Delbrueckii, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lactobacillus Delbrueckii. Your product may carry other ingredients that interact with Methenamine Mandelate too, on top of Lactobacillus Delbrueckii — 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 Delbrueckii and Methenamine Mandelate 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 Delbrueckii
Top 25%

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

29 days ago today
Medication Methenamine Mandelate
Steady interest

#2,317 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 Delbrueckii

What is Lactobacillus Delbrueckii?

  • Digestive health
  • Lactose digestion support
  • Diarrhea
  • Gut microbiome balance
  • Immune support

Lactobacillus delbrueckii is a 'friendly' bacterium used in food fermentation and sold as a probiotic, often as part of multi-strain products. It is generally considered safe for healthy people, but solid human evidence for most specific health claims is limited. Talk to a pharmacist or doctor before using it, especially if you have a weakened immune system or serious illness.

Read the full Lactobacillus Delbrueckii monograph & all interactions
Medication

About Methimazole

What Is Methimazole Used For?

Brand names: Mandelamine, Methimazole

Methimazole tablets treat hyperthyroidism in people with Graves’ disease or toxic multinodular goiter (a enlarged thyroid with overactive lumps). They are used when surgery or radioactive iodine is not a suitable option.

They are also used to ease hyperthyroid symptoms while a person gets ready for thyroidectomy (thyroid removal surgery) or radioactive iodine therapy.

See full Methimazole drug information Methimazole NDC codes and packages
Keep checking

Other Drugs & Lactobacillus Delbrueckii

Browse every other medication we’ve checked against Lactobacillus Delbrueckii — 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 Delbrueckii page.

No interaction 2,648 drugs checked — show the list

We also checked Lactobacillus Delbrueckii 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 Delbrueckii list.

See the full Lactobacillus Delbrueckii interactions page
See every supplement checked against Methenamine Mandelate, 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 Delbrueckii monograph › Uses, safety, and every drug interaction in one place Methenamine Mandelate supplement interactions › Every supplement checked against Methenamine Mandelate, ranked by severity Methimazole drug information › The full plain-English guide to this medication Methimazole NDC codes and packages › Every package, labeler and price in the FDA directory 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 Delbrueckii and Methenamine Mandelate Together: Common Questions

Can you take Lactobacillus Delbrueckii with Methenamine Mandelate?
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 Delbrueckii and Methenamine Mandelate 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 Methenamine Mandelate and Lactobacillus Delbrueckii?

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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.