Drug & supplement interaction

Lactobacillus Crispatus + Levothyroxine

Levothyroxine brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Lactobacillus Crispatus and Levothyroxine 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 label for Levothyroxine states a food rule worth keeping to, and 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.

Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Lactobacillus Crispatus and Levothyroxine

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 Levothyroxine and Lactobacillus Crispatus 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 Crispatus safety at a glance

Lactobacillus Cris... overall Use caution Generally considered safe for healthy people, but quality and evidence vary by product.
Pregnancy Use caution Limited safety data; use only under the guidance of your doctor.
Breastfeeding Use caution Not well studied during breastfeeding; check with your doctor first.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Levothyroxine and Lactobacillus Crispatus? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Levothyroxine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine is filed under 3 classifications — including thyroid hormone, oral drugs. Lactobacillus Crispatus has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Levothyroxine’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 Crispatus Does Interact With Other Medications

Lactobacillus Crispatus has 182 moderate known drug interactions in our database — Levothyroxine 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. Levothyroxine)
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.

What to actually watch for

No Interaction Found — But Data Suggests Lactobacillus Crispatus and Levothyroxine 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.

  • Nausea Additional detail

    Lactobacillus Crispatus

    “Orally, taking Lactobacillus crispatus has rarely caused nausea, gas, and flatulence in clinical research.”

    Lactobacillus Crispatus · Natural Medicines adverse-effect record, reported in flatulence.

    2 sources cited
    1. 110942. DI Pierro F, Criscuolo AA, Dei Giudici A, et al. Oral administration of Lactobacillus crispatus M247 to papillomavirus-infected women: results of a preliminary, uncontrolled, open trial. Minerva Obstet Gynecol 2021;73(5):621-631. PubMed
    2. 110946. Dellino M, Cascardi E, Laganà AS, et al. Lactobacillus crispatus M247 oral administration: Is it really an effective strategy in the management of papillomavirus-infected women?. Infect Agent Cancer 2022;17(1):53. PubMed

    Levothyroxine

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

Reported for Lactobacillus Crispatus but not commonly for Levothyroxine: bloating or gas and a higher chance of infection.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Lactobacillus Crispatus come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

How to take them

Some Levothyroxine Products Have a Food Rule — Lactobacillus Crispatus Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Lactobacillus Crispatus included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Levothyroxine on its own and move Lactobacillus Crispatus to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Levothyroxine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Lactobacillus Crispatus or Levothyroxine

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 Levothyroxine, 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 Levothyroxine

This page covers Lactobacillus Crispatus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine page lists 50 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Tiratricol (major), Acetyl-l-carnitine (moderate), Alpha-lipoic Acid (moderate) and Ascophyllum Nodosum (moderate).

By severity: 2 major · 39 moderate · 9 minor.

From our pharmacist’s overview on the Levothyroxine page

“Levothyroxine replaces a hormone your body measures in tiny amounts, so small shifts in its blood level show up in how you feel, and I treat this list with genuine care. Nearly everything on it does one of two things: blocks the pill from being absorbed in the gut, the way everyday minerals like calcium do by binding it into complexes,…”

Reviewed by 2 · Jul 18, 2026

Open the Levothyroxine 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. Even though Lactobacillus Crispatus itself has no known interaction with Levothyroxine, 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 Crispatus and Levothyroxine 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

#1,030 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Levothyroxine
Top 10

#2 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 Crispatus reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Lactobacillus Crispatus and Levothyroxine 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 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.

Lactobacillus crispatus · Lactobacillaceae · Live bacterial cells (probiotic strain) · Oral capsules, vaginal capsules or suppositories, powders, some yogurts and fermented foods

An interaction check asks whether these two react with each other — it does not ask whether Lactobacillus Crispatus is a good idea for someone in your situation. Here is what our Lactobacillus Crispatus record says about it on its own.

Lactobacillus Crispatus: dosing

There is no single standardized dose of Lactobacillus crispatus. Probiotic doses are usually measured in colony-forming units (CFU), and the right amount can vary by product and by why you are using it.The best approach is to follow the directions on the product label for the specific oral or vaginal product you have chosen.

From our Lactobacillus Crispatus monograph — the full record covers uses, side effects and every documented interaction.

Read the full Lactobacillus Crispatus monograph & all interactions
Medication

About Levothyroxine

What Is Levothyroxine Used For?

Brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, Levo-T, Eltroxin, Estre, Levothyroxine, Novothyrox, Levolet

Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain.

It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

See full Levothyroxine 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
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 Crispatus page.

No interaction 2,647 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 2,647 medications checked with no known interaction — see the full Lactobacillus Crispatus list.

See the full Lactobacillus Crispatus interactions page
See every supplement checked against Levothyroxine, ranked by severity
Evidence & sources

Lactobacillus Crispatus References

The 9 references that drive our Lactobacillus Crispatus 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
  3. Ranchal P, Gupta R, Goldberg R, A Lobo S, Pascual A, El Khoury MY. Penicillin-sensitive Lactobacillus jensenii bacteremia. Am J Ther 2021;28(2):e250-e252. PubMed
  4. Grazioli-Gauthier L, Rigamonti E, Leo LA, Martinetti Lucchini G, Lo Priore E, Bernasconi E. Lactobacillus jensenii mitral valve endocarditis: Case report, literature review and new perspectives. IDCases 2022;27:e01401. PubMed
  5. Toprak NU, Bozan T, Yilmaz S, Buyukbayrak EE, Tigen ET. Polymicrobial bacteremia due to Lactobacillus jensenii and Veillonella montpellierensis in a pregnant patient; case report and review of literature. Anaerobe 2022;75:102576. PubMed
  6. Chazan B, Raz R, Shental Y, Sprecher H, Colodner R. Bacteremia and pyelonephritis caused by Lactobacillus jensenii in a patient with urolithiasis. Isr Med Assoc J 2008;10(2):164-5.
  7. DI Pierro F, Criscuolo AA, Dei Giudici A, et al. Oral administration of Lactobacillus crispatus M247 to papillomavirus-infected women: results of a preliminary, uncontrolled, open trial. Minerva Obstet Gynecol 2021;73(5):621-631. PubMed
  8. DE Leo V, Lazzeri E, Governini L, et al. Vaginal colonization of women after oral administration of Lactobacillus crispatus strain NTCVAG04 from the human microbiota. Minerva Obstet Gynecol 2022. PubMed
  9. Dellino M, Cascardi E, Laganà AS, et al. Lactobacillus crispatus M247 oral administration: Is it really an effective strategy in the management of papillomavirus-infected women?. Infect Agent Cancer 2022;17(1):53. 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 Crispatus and Levothyroxine Together: Common Questions

Is it safe to take Lactobacillus Crispatus with Levothyroxine?
We do not list a known interaction between Lactobacillus Crispatus and Levothyroxine. 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 Crispatus and Levothyroxine 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.
Should I take Lactobacillus Crispatus and Levothyroxine at the same time of day?
At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Levothyroxine on its own and move Lactobacillus Crispatus to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Lactobacillus Crispatus and Levothyroxine combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Lactobacillus Crispatus has documented interactions with 1 drug class — none of Levothyroxine'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 Crispatus interact with any other medications?
Yes. Lactobacillus Crispatus has 182 documented drug interactions in our database — Levothyroxine 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 Levothyroxine interact with any supplements?
Yes. Levothyroxine has documented interactions with 50 supplements in our database — Lactobacillus Crispatus is not one of them. The Levothyroxine 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 Crispatus monograph Uses, safety profile, and every drug interaction in one place Levothyroxine drug information The full plain-English guide to this medication Levothyroxine supplement interactions Every supplement checked against Levothyroxine, 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 9 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Lactobacillus Crispatus?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.