Drug & supplement interaction

Lacticaseibacillus Paracasei + 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 Lacticaseibacillus Paracasei 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.

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Interaction report

Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei 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.

Lacticaseibacillus Paracasei safety at a glance

Lacticaseibacillus... overall Use caution Generally well tolerated in healthy people, but caution is needed for those who are seriously ill or have weakened immune systems.
Pregnancy Possibly Safe When used orally and appropriately. A combination of Lacticaseibacillus paracasei and Bifidobacterium longum from 2 months prior to delivery until 2 months afte... Read the full pregnancy detail
Breastfeeding Possibly Safe When used orally and appropriately. A combination of Lacticaseibacillus paracasei and Bifidobacterium longum from 2 months prior to delivery until 2 months afte... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Levothyroxine and Lacticaseibacillus Paracasei? 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. Lacticaseibacillus Paracasei 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

Lacticaseibacillus Paracasei Does Interact With Other Medications

Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei

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

What to actually watch for

No Interaction Found — But Data Suggests Lacticaseibacillus Paracasei and Levothyroxine May Share Several of the Same Side Effects

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.

  • Itching / A skin rash Additional detail

    Lacticaseibacillus Paracasei

    “Orally, in one clinical trial, a combination of Lacticaseibacillus paracasei subsp. paracasei F19, Lactobacillus acidophilus La-5, and Bifidobacterium animalis subsp. lactis BB-12 was associated with two cases of rash, one with itching. However, it is not clear if these adverse effects were due to L.”

    Lacticaseibacillus Paracasei · Natural Medicines adverse-effect record, reported in erythema.

    2 sources cited
    1. 90236. Begtrup LM, de Muckadell OB, Kjeldsen J, Christensen RD, Jarbøl DE. Long-term treatment with probiotics in primary care patients with irritable bowel syndrome--a randomised, double-blind, placebo controlled trial. Scand J Gastroenterol 2013;48(10):1127-35 PubMed
    2. 111945. Sathikulpakdee S, Kanokrungsee S, Vitheejongjaroen P, Kamanamool N, Udompataikul M, Taweechotipatr M. Efficacy of probiotic-derived lotion from Lactobacillus paracasei MSMC 39-1 in mild to moderate acne vulgaris, randomized controlled trial. J Cosmet Derm

    Levothyroxine

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

  • Nausea Additional detail

    Lacticaseibacillus Paracasei

    “Orally, taking Lacticaseibacillus paracasei alone or in combination with other probiotics may cause gastrointestinal side effects including dyspepsia, flatulence, nausea, and bloating; however, these events are uncommon.

    There are at least five case reports of acute cholecystitis for which a lactobacilli was thought to be the primary pathogen. In a 66-year-old female, vancomycin-resistant L.”

    Lacticaseibacillus Paracasei · Natural Medicines adverse-effect record, reported in dyspepsia.

    4 sources cited
    1. 105133. Cai T, Gallelli L, Cione E, et al. The use of Lactobacillus casei DG® prevents symptomatic episodes and reduces the antibiotic use in patients affected by chronic bacterial prostatitis: results from a phase IV study. World J Urol. 2021. DOI
    2. 107497. Kumar S, Kumar R, Rohilla L, Jacob N, Yadav J, Sachdeva N. A high potency multi-strain probiotic improves glycemic control in children with new-onset type 1 diabetes mellitus: A randomized, double-blind, and placebo-controlled pilot study. Pediatr Diabete
    3. 111952. Thijssen AY, Clemens CH, Vankerckhoven V, Goossens H, Jonkers DM, Masclee AA. Efficacy of Lactobacillus casei Shirota for patients with irritable bowel syndrome. Eur J Gastroenterol Hepatol 2016;28(1):8-14. PubMed
    4. 103443. Lee C, Wongjarupong N, Narayan M, Melzer AC. Acute cholecystitis complicated with gallbladder perforation and peritonitis caused by vancomycin-resistant Lactobacillus paracasei. Cureus. 2020;12(3):e7476. PubMed

    Levothyroxine

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

Reported for Lacticaseibacillus Paracasei but not commonly for Levothyroxine: bloating or gas, a higher chance of infection and stomach upset.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Lacticaseibacillus Paracasei 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.

Special populations

Lacticaseibacillus Paracasei in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Safe

When used orally and appropriately. A combination of Lacticaseibacillus paracasei and Bifidobacterium longum from 2 months prior to delivery until 2 months after delivery has been used with apparent safety.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

How to take them

Some Levothyroxine Products Have a Food Rule — Lacticaseibacillus Paracasei Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei 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.

Overlapping uses

What Levothyroxine Is Prescribed For, and What Lacticaseibacillus Paracasei Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Levothyroxine is a prescription medicine with approved uses on its FDA label. Lacticaseibacillus Paracasei is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Levothyroxine is prescribed for: 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.

Lacticaseibacillus Paracasei has been studied for:

  • Constipation studied, not established Lacticaseibacillus Paracasei has been studied for this. Natural Medicines rates the evidence: Possibly Ineffective Read what the research shows

    Lacticaseibacillus Paracasei for constipation

    Oral Lacticaseibacillus paracasei does not seem to be beneficial for constipation.

  • Depression studied, not established Lacticaseibacillus Paracasei has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Lacticaseibacillus Paracasei for depression

    Although there has been interest in using oral Lacticaseibacillus paracasei for depression, there is insufficient reliable information about the clinical effects of L. paracasei for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Levothyroxine on your own; if you are taking Lacticaseibacillus Paracasei for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei 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

How much people look this up

Where Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei
Steady interest

#1,202 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 Lacticaseibacillus Paracasei reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei

What is Lacticaseibacillus Paracasei?

  • Digestive health and regularity
  • Immune support
  • Diarrhea (including antibiotic-associated)
  • Allergy and eczema symptoms
  • Gut microbiome balance

Lacticaseibacillus paracasei (formerly Lactobacillus paracasei) is a probiotic bacterium found in fermented foods and supplements that is widely used to support gut and immune health. Some strains have promising research for digestion, diarrhea, and allergies, but results vary by strain and many uses are not firmly proven. It is generally well tolerated in healthy people, but those who are seriously ill or immune-compromised should check with a doctor first.

Lacticaseibacillus paracasei · Lactobacillaceae · Live bacterial cells (probiotic strain) · Capsules, tablets, powders, sachets, fermented dairy products (yogurt, kefir), and functional foods

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

Lacticaseibacillus Paracasei: dosing

There is no single official or standardized dose of L. paracasei. Probiotic doses are usually measured in colony-forming units (CFU), and the right amount can depend on the strain and the intended use.Because formulations differ, the best approach is to follow the dose on the product label. Storing the product as directed (some need refrigeration) helps keep the bacteria alive and effective.

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

Read the full Lacticaseibacillus Paracasei 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 & Lacticaseibacillus Paracasei

Browse every other medication we’ve checked against Lacticaseibacillus Paracasei — 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 Lacticaseibacillus Paracasei page.

No interaction 2,647 drugs checked — show the list

We also checked Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei list.

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

Lacticaseibacillus Paracasei References

The 16 references that drive our Lacticaseibacillus Paracasei 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. Begtrup LM, de Muckadell OB, Kjeldsen J, Christensen RD, Jarbøl DE. Long-term treatment with probiotics in primary care patients with irritable bowel syndrome--a randomised, double-blind, placebo controlled trial. Scand J Gastroenterol 2013;48(10):1127-35 PubMed
  3. Franko B, Vaillant M, Recule C, Vautrin E, Brion JP, Pavese P. Lactobacillus paracasei endocarditis in a consumer of probiotics. Med Mal Infect 2013;43(4):171-3. PubMed
  4. Orkaby AR, Chen B, Iliaki EF, Sulis CA, Oates DJ. A curious case of Lactobacillus casei in a prosthetic joint: was it the yogurt? J Am Geriatr Soc. 2012;60(6):1177-8.
  5. Rautava S, Kainonen E, Salminen S, Isolauri E. Maternal probiotic supplementation during pregnancy and breast-feeding reduces the risk of eczema in the infant. J Allergy Clin Immunol. 2012;130(6):1355-60. PubMed
  6. Kato K, Funabashi N, Takaoka H, et al. Lactobacillus paracasei endocarditis in a consumer of probiotics with advanced and severe bicuspid aortic valve stenosis complicated with diffuse left ventricular mid-layer fibrosis. Int J Cardiol 2016;224:157-61. PubMed
  7. Lee C, Wongjarupong N, Narayan M, Melzer AC. Acute cholecystitis complicated with gallbladder perforation and peritonitis caused by vancomycin-resistant Lactobacillus paracasei. Cureus. 2020;12(3):e7476. PubMed
  8. Cai T, Gallelli L, Cione E, et al. The use of Lactobacillus casei DG® prevents symptomatic episodes and reduces the antibiotic use in patients affected by chronic bacterial prostatitis: results from a phase IV study. World J Urol. 2021. DOI
  9. Kumar S, Kumar R, Rohilla L, Jacob N, Yadav J, Sachdeva N. A high potency multi-strain probiotic improves glycemic control in children with new-onset type 1 diabetes mellitus: A randomized, double-blind, and placebo-controlled pilot study. Pediatr Diabete
  10. 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
  11. Campbell RE, Miller A, Afroze A. Native valve endocarditis secondary to Lactobacillus paracasei bacteremia. Consultant. 2020;60(9):27-8. DOI
  12. Harding-Theobald E, Maraj B. Spontaneous bacterial peritonitis due to Lactobacillus paracasei in cirrhosis. Case Rep Gastrointest Med 2018;2018:5714053.
  13. Tan C, Howard JL, Bondy L. Prosthetic joint infection after total hip arthroplasty caused by Lactobacillus paracasei. CMAJ 2020;192(44):E1357-E1360.
  14. Sathikulpakdee S, Kanokrungsee S, Vitheejongjaroen P, Kamanamool N, Udompataikul M, Taweechotipatr M. Efficacy of probiotic-derived lotion from Lactobacillus paracasei MSMC 39-1 in mild to moderate acne vulgaris, randomized controlled trial. J Cosmet Derm
  15. Miwa T, Tanaka H, Shiojiri T. Infected pancreatic necrosis and retroperitoneal abscess associated with Lactobacillus paracasei. BMJ Case Rep 2021;14(8):e243936.

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 Lacticaseibacillus Paracasei and Levothyroxine Together: Common Questions

Is it safe to take Lacticaseibacillus Paracasei with Levothyroxine?
We do not list a known interaction between Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei and Levothyroxine have any of the same side effects?
Yes — our sources link each of them separately to 3 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 Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei 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.
Are Lacticaseibacillus Paracasei and Levothyroxine used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Lacticaseibacillus Paracasei in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.
How was the Lacticaseibacillus Paracasei and Levothyroxine combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Lacticaseibacillus Paracasei 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 Lacticaseibacillus Paracasei interact with any other medications?
Yes. Lacticaseibacillus Paracasei 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 — Lacticaseibacillus Paracasei 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

Lacticaseibacillus Paracasei 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 16 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Lacticaseibacillus Paracasei?

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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.