Herb & supplement monograph

Brewer's Yeast Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Brewer's Yeast interacts with medications. The heart of this page is the interaction list — every drug Brewer's Yeast is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Brewer's Yeast is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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On this page

Brewer's Yeast Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Brewer's Yeast drug interaction is low for most people, but a few medicines deserve real caution. Most listed interactions are rated moderate or minor, and the small number of major ones involve a single class of older antidepressants.

Interactions deserving the most attention

The clearest concern is with MAOIs (monoamine oxidase inhibitors). Brewer's yeast contains tyramine, which people on these antidepressants must avoid because the combination can trigger a dangerous spike in blood pressure. There is also human research showing that chromium-containing brewer's yeast can lower blood sugar, so anyone taking diabetes medications could see stronger glucose-lowering effects and should watch for signs of low blood sugar. Some brewer's yeast products also contain small amounts of lithium, which could theoretically add to the effects of prescription lithium.

What the rest of the list means

A long list of interacting medications does not mean every combination is harmful. Many of the moderate ratings reflect predicted or theoretical effects rather than problems documented in people. One interaction even works the other way: antifungal medicines may kill the live yeast in some products, making the supplement less effective rather than causing harm.

Check your medications against Brewer's Yeast

Based on HelloPharmacist’s Brewer's Yeast interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Brewer's Yeast

136 medications have a known interaction with Brewer's Yeast, graded by severity. Select any drug for the full evidence-based detail.

9 major interactions. These combinations can be clinically significant — best avoided, or used only with close professional supervision. Always check with your pharmacist before combining them with Brewer's Yeast.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Brewer's Yeast using our pharmacist-reviewed interaction data.

AI summaries are generated from our Brewer's Yeast interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Brewer's Yeast combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Brewer's Yeast affects

Every type of medication (drug category) Brewer's Yeast is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 4 drug categories Brewer's Yeast interacts with

Monoamine Oxidase Inhibitors (maois)Antidiabetes DrugsLithiumAntifungals

Monoamine Oxidase Inhibitors (Maois)

Theoretically, taking brewer's yeast with MAOIs might increase the risk of hypertension.
Brewer's yeast contains tyramine. Taking brewer's yeast with MAOIs might increase the risk for hypertensive crisis.

Likelihood Likely Evidence D

Antidiabetes Drugs

Taking brewer's yeast with antidiabetes drugs might increase the risk of hypoglycemia.
Clinical research shows that taking chromium-containing brewer's yeast can decrease levels of blood glucose in diabetic patients being treated with antidiabetes drugs.

Likelihood Possible Evidence B

Lithium

Theoretically, taking brewer's yeast with lithium might cause additive effects and side effects.
Some brewer's yeast products contains lithium.

Likelihood Possible Evidence D

Antifungals

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.

Likelihood Possible Evidence D

Monograph

Brewer's Yeast: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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.

Scientific name: Saccharomyces cerevisiae
Family: Saccharomycetaceae
Part used: Whole dried yeast cells (and their fermentation products)
Common forms: Tablets, capsules, powder, flakes, liquid

People commonly use it for

Source of B vitamins
Diarrhea (certain types)
Cold and flu support
Digestive health
Acne and skin health
Blood sugar support

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated in food amounts, but it can cause gas and may not be safe for people with weakened immune systems or certain conditions.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Brewer's yeast is a type of one-celled fungus called Saccharomyces cerevisiae. It is the same species used to brew beer and bake bread, though specific strains can differ. For supplements, the yeast is usually grown, then dried and processed into tablets, capsules, powder, or flakes.

People have used brewer's yeast for a long time as a food and a nutritional supplement. It is naturally rich in B vitamins, protein, and minerals such as chromium and selenium. "Nutritional yeast" is a related, often fortified product used as a savory, cheese-like seasoning.

A closely related yeast, Saccharomyces boulardii, is sold as a probiotic and is studied separately for digestive problems. It is worth knowing that not all "yeast" supplements are the same.

How it works

Brewer's yeast is mostly valued for its nutritional content. It supplies B vitamins (such as B1, B2, B3, and others), protein, beta-glucans (a type of fiber found in the cell wall), and minerals like chromium and selenium.

Beta-glucans in the yeast cell wall are thought to interact with the immune system, and chromium is involved in how the body handles blood sugar. Much of the research on these effects comes from laboratory and animal studies, so it is not certain how meaningful they are in people.

The probiotic yeast S. boulardii is believed to work in the gut by helping crowd out harmful organisms and supporting the gut lining. This mechanism applies to that specific yeast, not necessarily to ordinary brewer's yeast.

Effectiveness

Does Brewer's Yeast work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 11 uses evaluated

1 Possibly effective 10 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Irritable bowel syndrome (IBS)