Drug & supplement interaction

Lactobacillus Crispatus + Doxycyline

Doxycyline brand name: Doxychel.

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

Lactobacillus Crispatus has a moderate interaction with Doxycyline. Theoretically, taking Lactobacillus crispatus 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 Crispatus and Doxycyline

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

Moderate

ANTIBIOTIC DRUGS

Why this applies to Doxycyline

Doxycyline falls under ANTIBIOTIC DRUGS — the group Lactobacillus Crispatus interacts with.

Theoretically, taking Lactobacillus crispatus with antibiotic drugs might decrease the effectiveness of L. crispatus.
Lactobacillus crispatus 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. crispatus 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: this interaction works the opposite of what people usually worry about. Doxycycline isn't affected by the probiotic at all. Instead, it's the probiotic that takes the hit. Doxycycline is an antibiotic, and its whole job is to kill bacteria. Since Lactobacillus crispatus is made up of live, friendly bacteria, taking the two at the same time means the doxycycline can wipe out a good chunk of those probiotic organisms before they ever get to work.

This won't make your doxycycline weaker or stronger, and it won't cause new side effects. To get the most out of the probiotic, a simple fix helps: separate the two doses by at least two hours. This is based on how these products work rather than hard human studies, so it's a sensible precaution, not a major danger. Your pharmacist can help you time them.

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 Crispatus Also Interacts With Other Medications

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

Check Another of Your Medications Against Lactobacillus Crispatus

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

From our Q&A

Questions About Lactobacillus Crispatus or Doxycyline

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 Crispatus or Doxycyline, 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 Doxycyline

This page covers Lactobacillus Crispatus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Doxycyline page lists 149 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Asarabacca (major), Beer (major), Oleander (major), Siberian Cocklebur (major) and St. John's Wort (major).

By severity: 6 major · 132 moderate · 11 minor.

From our pharmacist’s overview on the Doxycyline page

“I read the supplement list for doxycycline (Doxychel) as one to approach with real care, starting with its major-rated entries. Heavy alcohol, including beer and wine, adds to the liver strain this antibiotic can cause, botanicals such as Siberian cocklebur can compound stress on the kidneys, and St.”

Reviewed by 2 · Jul 18, 2026

Open the Doxycyline interaction page

One more smart check

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

We hold 48 real supplement products containing Lactobacillus Crispatus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lactobacillus Crispatus. Your product may carry other ingredients that interact with Doxycyline too, on top of Lactobacillus Crispatus — 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 Crispatus and Doxycyline 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 Crispatus
Steady interest

#1,073 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Doxycyline
Top half

#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.

Supplement

About Lactobacillus Crispatus

What is Lactobacillus Crispatus?

  • Vaginal health support
  • Preventing recurrent bacterial vaginosis
  • Reducing recurrent urinary tract infections
  • Yeast infection support
  • General microbiome balance

Lactobacillus crispatus is a 'good' bacterium that naturally dominates a healthy vaginal microbiome and is sold as a probiotic, mainly for vaginal and urinary health. Early research is promising for preventing recurrent bacterial vaginosis and urinary tract infections, but evidence is still limited and product quality varies. Talk with your pharmacist or doctor before using it, especially if you are pregnant or have a weakened immune system.

Read the full Lactobacillus Crispatus monograph & all interactions
Medication

About Doxycycline

What Is Doxycycline Used For?

Brand name: Doxychel

Doxycycline belongs to the tetracycline family of antibiotics. It's prescribed for many types of bacterial infections, including respiratory tract infections, sexually transmitted infections (STIs), tick-borne illnesses like Rocky Mountain spotted fever, and eye infections. It's also used to help prevent malaria and, in some cases, as a helper treatment for severe acne.

In situations where penicillin-type antibiotics can't be used — due to allergy, for example — doxycycline can step in as an alternative. It should only be used for infections that are proven or strongly suspected to be caused by bacteria.

See full Doxycycline drug information
Keep checking

Other Drugs & Lactobacillus Crispatus

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

No interaction 2,648 drugs checked — show the list

We also checked Lactobacillus Crispatus 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 Crispatus list.

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

Can you take Lactobacillus Crispatus with Doxycyline?
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 Crispatus and Doxycyline 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 Doxycyline and Lactobacillus Crispatus?

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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.