Drug & supplement interaction

Bacillus Subtilis + Psyllium (OTC drug)

Psyllium (OTC drug) brand name: Metamucil.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between Bacillus Subtilis and Psyllium (OTC drug) 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.

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Interaction report

Bacillus Subtilis and Psyllium (OTC drug)

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 Psyllium (OTC drug) and Bacillus Subtilis 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.

Bacillus Subtilis safety at a glance

Bacillus Subtilis overall Use caution Generally well tolerated in healthy adults, but quality and safety can vary by product and strain.
Pregnancy Use caution There is not enough safety data, so it is best to avoid unless a doctor advises otherwise.
Breastfeeding Use caution Limited safety information exists, so check with your doctor before use.

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

Still wondering about combining Psyllium (OTC drug) and Bacillus Subtilis? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Psyllium (OTC drug)

Interactions in our licensed database are recorded against drug classes, not just single drug names. Psyllium (OTC drug) is filed under a single classification — oral drugs. Bacillus Subtilis has documented interactions with 1 drug class — the most serious being antibiotic drugs (moderate) — and none of Psyllium (OTC drug)’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

Bacillus Subtilis Does Interact With Other Medications

Bacillus Subtilis has 182 moderate known drug interactions in our database — Psyllium (OTC drug) 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. Psyllium (OTC drug))
Taking anything else?

Check Another of Your Medications Against Bacillus Subtilis

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

What to actually watch for

What Bacillus Subtilis Itself Has Been Linked To

This is not an interaction — nothing below involves Psyllium (OTC drug). It is the side-effect record for Bacillus Subtilis on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Bacillus Subtilis, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • Kidney problems / A higher chance of infection Worth acting on Additional detail

    “There are cases of Bacillus subtilis var. natto bacteremia and meningitis in patients with frequent consumption of natto, soybeans fermented with B. subtilis var. natto. A 70-year-old female recovered from bacteremia after this consumption was stopped and she was treated with vancomycin.”

    Bacillus Subtilis · Natural Medicines adverse-effect record, reported in diabetes.

    6 sources cited
    1. 110844. Kato A, Yoshifuji A, Komori K, et al. A case of Bacillus subtilis var. natto bacteremia caused by ingestion of natto during COVID-19 treatment in a maintenance hemodialysis patient with multiple myeloma. J Infect Chemother 2022;28(8):1212-1215. PubMed
    2. 110862. Tokano M, Tarumoto N, Imai K, et al. A case of bacterial meningitis caused by Bacillus subtilis var. natto. Intern Med. 2022. Epub ahead of print.
    3. 110834. Lampropoulos PK, Gkentzi D, Tzifas S, Dimitriou G. Neonatal sepsis due to Bacillus subtilis. Cureus 2021;13(9):e17692. PubMed
    4. 110837. La Jeon Y, Yang JJ, Kim MJ, et al. Combined Bacillus licheniformis and Bacillus subtilis infection in a patient with oesophageal perforation. J Med Microbiol 2012;61(Pt 12):1766-1769. PubMed
    5. 110840. Velasco E, Martins CA, Tabak D, Bouzas LF. "Bacillus subtilis" infection in a patient submitted to a bone marrow transplantation. Rev Paul Med 1992;110(3):116-7.
    6. 110838. Wallet F, Crunelle V, Roussel-Delvallez M, Fruchart A, Saunier P, Courcol RJ. Bacillus subtilis as a cause of cholangitis in polycystic kidney and liver disease. Am J Gastroenterol 1996;91(7):1477-8.
  • Itching Additional detail

    “Orally, itching and redness were reported rarely.”

    Bacillus Subtilis · Natural Medicines adverse-effect record, reported in pruritus.

    1 source cited
    1. 110848. Hanifi A, Culpepper T, Mai V, et al. Evaluation of Bacillus subtilis R0179 on gastrointestinal viability and general wellness: a randomised, double-blind, placebo-controlled trial in healthy adults. Benef Microbes 2015;6(1):19-27. PubMed
  • Diarrhea Additional detail

    “Orally, diarrhea has been reported rarely.”

    Bacillus Subtilis · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 110846. Freedman KE, Hill JL, Wei Y, et al. Examining the gastrointestinal and immunomodulatory effects of the novel probiotic Bacillus subtilis DE111. Int J Mol Sci 2021;22(5):2453. PubMed
  • Headache Additional detail

    “Orally, one case of headache was reported in a clinical trial.”

    Bacillus Subtilis · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 110847. Lefevre M, Racedo SM, Denayrolles M, et al. Safety assessment of Bacillus subtilis CU1 for use as a probiotic in humans. Regul Toxicol Pharmacol 2017;83:54-65. PubMed

Everything above comes from the Natural Medicines adverse-effect record for Bacillus Subtilis — expand a row for the licensed statement it rests on. We haven’t matched Psyllium (OTC drug) to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Psyllium (OTC drug).

Overlapping uses

What Psyllium (OTC drug) Is Prescribed For, and What Bacillus Subtilis Has Been Studied For

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

Psyllium (OTC drug) is prescribed for: Psyllium is used to treat occasional constipation and help restore regularity. It is available under many brand names — including Careone, Best Choice, Premier Value Fiber, fiber laxative, meijer fiber laxative, Publix, Best Choice Fiber Therapy, Daily Fiber, Dr. Fibra, Lidl Orange Smooth Fiber Powder, and meijer fiber therapy — all for this same purpose. Most products note that psyllium generally produces a bowel movement within 12 to 72 hours of taking a dose.

Bacillus Subtilis has been studied for:

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

    Bacillus Subtilis for constipation

    Although there has been interest in using oral Bacillus subtilis for preventing constipation in infants, there is insufficient reliable information about the clinical effects of B. subtilis for this purpose.

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 Psyllium (OTC drug) on your own; if you are taking Bacillus Subtilis for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Bacillus Subtilis or Psyllium (OTC drug)

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Bacillus Subtilis or Psyllium (OTC drug), 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 Psyllium (OTC drug)

This page covers Bacillus Subtilis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Psyllium (OTC drug) page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Psyllium (OTC drug) page

“Activated charcoal tops the psyllium (Metamucil) list and is the one entry rated major. Charcoal binds many medicines in the gut and can cut how much of them reaches the body, so pairing it with anything you take by mouth deserves real caution, and I would read that entry before the rest.”

Reviewed by 2 · Jul 18, 2026

Open the Psyllium (OTC drug) interaction page

One more smart check

Taking Bacillus Subtilis as Part of a Dietary Supplement Product? Check It for Interactions

We hold 786 real supplement products containing Bacillus Subtilis, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bacillus Subtilis. Even though Bacillus Subtilis itself has no known interaction with Psyllium (OTC drug), 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 Bacillus Subtilis and Psyllium (OTC drug) 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 Bacillus Subtilis
Top 25%

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

29 days ago today
Medication Psyllium (OTC drug)
Top half

#1,160 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 Bacillus Subtilis reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The Bacillus Subtilis and Psyllium (OTC drug) 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 Bacillus Subtilis

What is Bacillus Subtilis?

  • Digestive health and bloating
  • Diarrhea support
  • Immune support
  • Gut microbiome balance

Bacillus subtilis is a spore-forming probiotic bacterium found in soil and some fermented foods, and it is used mainly to support gut health and digestion. Early research is promising for certain digestive and immune uses, but evidence is still limited and not strong enough to make firm claims. Talk to a pharmacist or doctor before using it, especially if you have a weak immune system.

Bacillus subtilis · Bacillaceae · Live bacterial cells and spores (probiotic strains) · Capsules, tablets, powders, and multi-strain probiotic blends

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

Bacillus Subtilis: dosing

There is no official standard dose for Bacillus subtilis. Probiotic amounts are usually measured in CFUs (colony-forming units), and products vary widely.The best approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full Bacillus Subtilis monograph & all interactions
Medication

About Psyllium

What Is Psyllium Used For?

Brand name: Metamucil

Psyllium is used to treat occasional constipation and help restore regularity. It is available under many brand names — including Careone, Best Choice, Premier Value Fiber, fiber laxative, meijer fiber laxative, Publix, Best Choice Fiber Therapy, Daily Fiber, Dr. Fibra, Lidl Orange Smooth Fiber Powder, and meijer fiber therapy — all for this same purpose.

Most products note that psyllium generally produces a bowel movement within 12 to 72 hours of taking a dose.

See full Psyllium drug information
Keep checking

Other Drugs & Bacillus Subtilis

Browse every other medication we’ve checked against Bacillus Subtilis — 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 Bacillus Subtilis page.

No interaction 2,647 drugs checked — show the list

We also checked Bacillus Subtilis 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 Bacillus Subtilis list.

See the full Bacillus Subtilis interactions page
See every supplement checked against Psyllium (OTC drug), ranked by severity
Evidence & sources

Bacillus Subtilis References

The 10 references that drive our Bacillus Subtilis 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. Lampropoulos PK, Gkentzi D, Tzifas S, Dimitriou G. Neonatal sepsis due to Bacillus subtilis. Cureus 2021;13(9):e17692. PubMed
  3. La Jeon Y, Yang JJ, Kim MJ, et al. Combined Bacillus licheniformis and Bacillus subtilis infection in a patient with oesophageal perforation. J Med Microbiol 2012;61(Pt 12):1766-1769. PubMed
  4. Wallet F, Crunelle V, Roussel-Delvallez M, Fruchart A, Saunier P, Courcol RJ. Bacillus subtilis as a cause of cholangitis in polycystic kidney and liver disease. Am J Gastroenterol 1996;91(7):1477-8.
  5. Velasco E, Martins CA, Tabak D, Bouzas LF. "Bacillus subtilis" infection in a patient submitted to a bone marrow transplantation. Rev Paul Med 1992;110(3):116-7.
  6. Kato A, Yoshifuji A, Komori K, et al. A case of Bacillus subtilis var. natto bacteremia caused by ingestion of natto during COVID-19 treatment in a maintenance hemodialysis patient with multiple myeloma. J Infect Chemother 2022;28(8):1212-1215. PubMed
  7. Freedman KE, Hill JL, Wei Y, et al. Examining the gastrointestinal and immunomodulatory effects of the novel probiotic Bacillus subtilis DE111. Int J Mol Sci 2021;22(5):2453. PubMed
  8. Lefevre M, Racedo SM, Denayrolles M, et al. Safety assessment of Bacillus subtilis CU1 for use as a probiotic in humans. Regul Toxicol Pharmacol 2017;83:54-65. PubMed
  9. Hanifi A, Culpepper T, Mai V, et al. Evaluation of Bacillus subtilis R0179 on gastrointestinal viability and general wellness: a randomised, double-blind, placebo-controlled trial in healthy adults. Benef Microbes 2015;6(1):19-27. PubMed
  10. Tokano M, Tarumoto N, Imai K, et al. A case of bacterial meningitis caused by Bacillus subtilis var. natto. Intern Med. 2022. Epub ahead of print.

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 Bacillus Subtilis and Psyllium (OTC drug) Together: Common Questions

Is it safe to take Bacillus Subtilis with Psyllium (OTC drug)?
We do not list a known interaction between Bacillus Subtilis and Psyllium (OTC drug). 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.
Are Bacillus Subtilis and Psyllium (OTC drug) 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 Bacillus Subtilis in each. That is a conversation for your prescriber, especially if Psyllium (OTC drug) is being adjusted to a target.
How was the Bacillus Subtilis and Psyllium (OTC drug) combination checked?
Interactions in our licensed database are recorded against drug classes. Psyllium (OTC drug) is filed under 1 classification, and Bacillus Subtilis has documented interactions with 1 drug class — none of Psyllium (OTC drug)'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 Bacillus Subtilis interact with any other medications?
Yes. Bacillus Subtilis has 182 documented drug interactions in our database — Psyllium (OTC drug) 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 Psyllium (OTC drug) interact with any supplements?
Yes. Psyllium (OTC drug) has documented interactions with 17 supplements in our database — Bacillus Subtilis is not one of them. The Psyllium (OTC drug) 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

Bacillus Subtilis monograph Uses, safety profile, and every drug interaction in one place Psyllium drug information The full plain-English guide to this medication Psyllium (OTC drug) supplement interactions Every supplement checked against Psyllium (OTC drug), 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 10 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Psyllium (OTC drug) and Bacillus Subtilis?

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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.