Drug & supplement interaction

Brewer's Yeast + Boric Acid

Boric Acid brand names: Boric Acid, Boric acid ointment.

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

Brewer's Yeast has a minor interaction with Boric Acid. Theoretically, taking antifungals with some brewer's yeast products might decrease the effectiveness of brewer's yeast.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Brewer's Yeast and Boric Acid

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

Minor

ANTIFUNGALS

Why this applies to Boric Acid

Boric Acid falls under ANTIFUNGALS — the group Brewer's Yeast interacts with.

Theoretically, taking antifungals with some brewer's yeast products might decrease the effectiveness of brewer's yeast.
Some brewer's yeast products contain live yeast. Therefore, simultaneously taking antifungals might kill a significant number of the organisms.
Severity Minor Likelihood Possible Evidence D

Interaction 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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for boric acid and brewer's yeast: this isn't a case of one harming you. The concern actually runs the other way. Some brewer's yeast supplements contain live yeast, and boric acid has mild antifungal and antimicrobial properties. So if they're in the same spot at the same time, the boric acid could kill off some of those live yeast organisms, making the brewer's yeast less effective.

I'll be honest, this is a theoretical interaction based on how these two work, not something well documented in real patients. It's rated minor. Also, boric acid is usually used vaginally (as a suppository) or topically, while brewer's yeast is taken by mouth, so they often don't even meet. If you use both regularly, just run it by your pharmacist to be safe.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lewis SJ, Freedman AR. Review article: the use of biotherapeutic agents in the prevention and treatment of gastrointestinal disease. Aliment Pharmacol Ther 1998;12:807-22. PubMed

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

Brewer's Yeast Also Interacts With Other Medications

Brewer's Yeast has 9 major, 87 moderate, 39 minor known drug interactions in our database — the Boric Acid one above is one of them. If you take anything else, check it against the full list below.

Major 9 Moderate 87 Minor 39 No known interaction 2,695 (incl. Boric Acid)
Taking anything else?

Check Another of Your Medications Against Brewer's Yeast

Covers the 2,830 medications we’ve checked against Brewer's Yeast. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Boric Acid

This page covers Brewer's Yeast only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Boric Acid page lists 23 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 1 major · 9 moderate · 13 minor.

From our pharmacist’s overview on the Boric Acid page

“Boric acid shows up as a vaginal suppository for stubborn yeast infections or as an antiseptic ointment, and I read its interaction list with genuine caution because of one entry above all. Activated charcoal, the single major-rated interaction of the 23 on file, adsorbs many medications and can shrink how much drug the body actually t…”

Reviewed by 2 · Jul 18, 2026

Open the Boric Acid interaction page

One more smart check

Taking Brewer's Yeast as Part of a Dietary Supplement Product? Check It for Interactions

We hold 126 real supplement products containing Brewer's Yeast, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Brewer's Yeast. Your product may carry other ingredients that interact with Boric Acid too, on top of Brewer's Yeast — 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 Brewer's Yeast and Boric Acid 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 Brewer's Yeast
Top half

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

29 days ago today
Medication Boric Acid
Steady interest

#1,792 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 Brewer's Yeast

What is Brewer's Yeast?

Brewer's Yeast
  • Source of B vitamins
  • Diarrhea (certain types)
  • Cold and flu support
  • Digestive health
  • Acne and skin health
  • Blood sugar support

Brewer's yeast is a nutrient-rich fungus that provides B vitamins, protein, and minerals, and a related yeast product (S. boulardii) is used for some types of diarrhea. Most other health claims have limited or weak evidence. It is generally well tolerated as a food or supplement, but talk to your pharmacist or doctor before using it regularly, especially if you have a weakened immune system.

Read the full Brewer's Yeast monograph & all interactions
Keep checking

Other Drugs & Brewer's Yeast

Browse every other medication we’ve checked against Brewer's Yeast — both the ones with a known interaction and the ones without. Select any drug for the full detail.

9Major
87Moderate
39Minor
2,694No known interaction
9 Major 87 Moderate 39 Minor 2,694 No interaction
Major

9 interactions

Moderate

87 interactions

Showing 60 of 87 moderate interactions — see all 87 on the Brewer's Yeast page.

Minor

39 interactions

No interaction 2,694 drugs checked — show the list

We also checked Brewer's Yeast against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,694 medications checked with no known interaction — see the full Brewer's Yeast list.

See the full Brewer's Yeast interactions page
See every supplement checked against Boric Acid, 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
Brewer's Yeast monograph › Uses, safety, and every drug interaction in one place Boric Acid supplement interactions › Every supplement checked against Boric Acid, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Brewer's Yeast and Boric Acid Together: Common Questions

Can you take Brewer's Yeast with Boric Acid?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Brewer's Yeast and Boric Acid interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Boric Acid and Brewer's Yeast?

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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.