Drug & supplement interaction

Lactobacillus Acidophilus + Aztreonam

Aztreonam brand name: Azactam.

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

Lactobacillus Acidophilus has a moderate interaction with Aztreonam. Theoretically, taking Lactobacillus acidophilus 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 Acidophilus and Aztreonam

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

Moderate

ANTIBIOTIC DRUGS

Why this applies to Aztreonam

Aztreonam falls under ANTIBIOTIC DRUGS — the group Lactobacillus Acidophilus interacts with.

Theoretically, taking Lactobacillus acidophilus with antibiotic drugs might decrease the effectiveness of L. acidophilus.
L. acidophilus 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. acidophilus 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 thing to keep in mind with this pairing: it's the probiotic that takes the hit, not your antibiotic. Aztreonam (Azactam) is given to wipe out certain bacteria causing your infection. The catch is that Lactobacillus acidophilus is itself a live, friendly bacterium, so an antibiotic on board can kill off a good chunk of those organisms before they ever do their job. Your aztreonam will still work just fine for your infection.

This is a theoretical concern based on how the two work, not a dangerous reaction. A simple fix is to space them out, taking your probiotic at least two hours apart from your antibiotic. If you have questions about timing, your pharmacist is happy to help you sort it out.

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 Acidophilus Also Interacts With Other Medications

Lactobacillus Acidophilus has 181 moderate known drug interactions in our database — the Aztreonam 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. Aztreonam)
Taking anything else?

Check Another of Your Medications Against Lactobacillus Acidophilus

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

Everything else you take

See Every Supplement That Interacts With Aztreonam

This page covers Lactobacillus Acidophilus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Aztreonam page lists 27 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Bacillus Coagulans (moderate), Bacillus Subtilis (moderate), Bifidobacterium Animalis Subsp. Lactis (moderate), Bifidobacterium Bifidum (moderate) and Bifidobacterium Breve (moderate).

By severity: 26 moderate · 1 minor.

From our pharmacist’s overview on the Aztreonam page

“Every entry on this page tells one story, and it is a gentler one than most interaction lists. Aztreonam (Azactam) is an injectable or inhaled antibiotic used for serious infections, often in people with cystic fibrosis, and none of these 27 supplement pairings makes the drug itself riskier or weaker.”

Reviewed by 2 · Jul 18, 2026

Open the Aztreonam interaction page

One more smart check

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

We hold 6,180 real supplement products containing Lactobacillus Acidophilus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lactobacillus Acidophilus. Your product may carry other ingredients that interact with Aztreonam too, on top of Lactobacillus Acidophilus — 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 Acidophilus and Aztreonam 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 Acidophilus
Top 5%

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

29 days ago today
Medication Aztreonam
Steady interest

#2,168 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 Acidophilus

What is Lactobacillus Acidophilus?

Lactobacillus Acidophilus
  • Digestive health and balance
  • Diarrhea (including antibiotic-related)
  • Vaginal yeast and bacterial infections
  • Lactose intolerance
  • General immune support

Lactobacillus acidophilus is a 'friendly' bacterium used as a probiotic to support gut and vaginal health. It is generally well tolerated in healthy people, and there is reasonable evidence it may help with certain types of diarrhea, but proof for many other uses is limited. People with weakened immune systems or serious illness should check with a doctor before using it.

Read the full Lactobacillus Acidophilus monograph & all interactions
Medication

About Aztreonam Injection

What Is Aztreonam Injection Used For?

Brand name: Azactam

Azactam (aztreonam for injection) is used to treat infections caused by susceptible gram-negative bacteria. It is approved for urinary tract infections (including kidney infections and bladder infections), lower respiratory tract infections (including pneumonia), bloodstream infections (septicemia), skin and skin-structure infections (including those related to wounds, ulcers, and burns), intra-abdominal infections (including peritonitis), and gynecologic infections (including endometritis and pelvic cellulitis).

Azactam is also used alongside surgery to manage infections such as abscesses and infections involving perforated organs. In seriously ill patients who may also have gram-positive bacterial infections, it is often started together with another antibiotic that covers those bacteria. When anaerobic bacteria (bacteria that don't need oxygen) are also suspected, an anti-anaerobic antibiotic is added as well.

See full Aztreonam Injection drug information
Keep checking

Other Drugs & Lactobacillus Acidophilus

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

No interaction 2,648 drugs checked — show the list

We also checked Lactobacillus Acidophilus 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 Acidophilus list.

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

Can you take Lactobacillus Acidophilus with Aztreonam?
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 Acidophilus and Aztreonam 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 Aztreonam and Lactobacillus Acidophilus?

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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.