Major interaction on record — check this product against your medications before combining. Based on 1 of 2 ingredients. Check your meds →
Dietary supplement

Brewer's Yeast 10 Grain, 650 mg Ingredients & Drug Interactions

by NOW

Brewer's Yeast 10 Grain, 650 mg label
See full label image
Tablet Or Pill Category: Botanical
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 30, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Brewer's Yeast 10 Grain, 650 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Brewer's Yeast 10 Grain, 650 mg is a dietary supplement by NOW with 2 active ingredients. Its ingredients are commonly taken for source of b vitamins, diarrhea (certain types), cold and flu support.Based on those ingredients, 136 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Brewer's Yeast, Dried. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Brewer's Yeast 10 Grain, 650 mg by NOW

Ask about any prescription or over-the-counter medication and we check it for interactions with Brewer's Yeast 10 Grain, 650 mg by NOW — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Brewer's Yeast 10 Grain, 650 mg by NOW

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Oct 1, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.

This product contains one active ingredient: dried brewer's yeast at 650 mg per tablet. Brewer's yeast is a type of fungus left over from beer brewing; it's rich in B vitamins, minerals, and protein.

The tablet also contains several inactive ingredients — hydroxypropyl cellulose, stearic acid, croscarmellose sodium, magnesium stearate, and silicon dioxide — which are binders and flow agents that help hold the tablet together.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed

This product doesn't appear to be marketed for a specific use, so we graded Brewer's Yeast's overall clinical evidence instead.

Moderate

Some clinical evidence supports Brewer's Yeast for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredient's overall clinical evidence instead.
  • On file: Irritable bowel syndrome (IBS) — rated "Possibly Effective" (Natural Medicines).

The evidence for brewer's yeast in irritable bowel syndrome (IBS) is listed as possibly effective, meaning there's some promising research but it's not conclusive. For other uses — clostridioides difficile infection, influenza, high cholesterol (hypercholesterolemia), and allergic rhinitis (hay fever) — the evidence we hold is insufficient to rate whether it works.

That doesn't mean it doesn't help with those conditions; it means the research we have access to isn't strong enough to say either way.

The evidence, ingredient by ingredient Brewer's Yeast

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Brewer's yeast is generally well tolerated when you take it short-term and in amounts similar to what you'd get from food. The most common side effects are flatulence (gas) and migraine.

Intestinal discomfort, anal irritation, and abdominal pain have been reported rarely. There's a theoretical concern that it could cause fungemia (yeast in the bloodstream) or anaphylaxis in sensitive people, though these are uncommon.

Brewer's yeast may not be safe for people with weakened immune systems or certain conditions — talk with your doctor if that applies to you. During pregnancy and breastfeeding, food amounts are likely fine, but the safety of supplement doses is not well studied, so check with your healthcare provider for personalized guidance.

Side effects, ingredient by ingredient Brewer's Yeast

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Brewer's Yeast.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: diabetes medications; lithium.
  • For scale: 136 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Before you start, double-check if you take any MAOIs (a Major interaction risk — dangerous rise in blood pressure), antidiabetes drugs or blood sugar medications (Moderate risk of low blood sugar), lithium (Moderate risk), or antifungal medications (Minor risk). If any of these apply, talk with your doctor or pharmacist about whether this product is right for you.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence behind its ingredients' uses. Major medication interactions have been identified, and safety information is well characterized.

Brewer's yeast may help with irritable bowel syndrome, but the evidence for other uses isn't established yet. If you take MAOIs, diabetes medications, lithium, or antifungals, you'll need to check with your doctor or pharmacist first — the interactions can be serious.

It's generally well tolerated, but expect possible gas or headache, and avoid it if you have a weakened immune system.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated May 23, 2024.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Brewer's Yeast 10 Grain, 650 mg, straight from the product label.

Brand NOW
Barcode (UPC) 733739024107
Net contents 200 Tablet(s)
Market status On market
Date entered into DSLD May 23, 2024
DSLD ID 313624
Product type Botanical
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other
Intended target group(s) Vegan, Vegetarian, Adult (18 - 50 Years), Kosher, Halal, Dairy Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Brewer's Yeast 10 Grain, 650 mg by NOW, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
3 Tablet(s)
Maximum serving Sizes:
3 Tablet(s)
Servings per container
66
UPC/BARCODE
733739024107
IngredientAmount% DV
Calories5 Calorie(s)--
Total Carbohydrates1 Gram(s)1%
Protein1 Gram(s)--
Brewer's Yeast, Dried1.95 Gram(s)--

Other ingredients: Hydroxypropyl Cellulose, Stearic Acid, Croscarmellose Sodium, Magnesium Stearate, Silicon Dioxide

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested usage: Take 3 tablets 3 times daily with food.

Formula

NOW Brewer’s Yeast has several naturally occurring vitamins and minerals, with most notably B-vitamins. In addition, Brewer's Yeast offers other components, such as amino acids and beta-glucans.

NOW Brewer’s Yeast is a genuine whole food supplement.

Brewer’s Yeast has naturally occurring B-vitamins such as: Thiamin (vitamin B-1), riboflavin (vitamin B-2), niacin, vitamin B-6, folic acid, biotin and pantothenic acid.

Crescent H (Halal)

Triangle K (Kosher)

Formulation

No synthetic vitamins are added to the yeast during processing.

Natural color variation may occur in this product.

Non-GMO

Nutritional supplement Easier to swallow tablet

Vegetarian/Vegan

Made and quality tested in the USA with globally sourced ingredients.

Not manufactured with soy, milk, egg, shellfish, tree nut or sesame ingredients.

Precautions

Caution: For adults only.

Brewer's yeast has significant amounts of tyramine.

Consult physician if taking an MAO inhibitor or other medication, if pregnant/nursing, or if you have Crohn's Disease, or other medical condition.

Keep out of reach of children.

Contains wheat. Brewer's yeast is derived from barley and wheat. Not manufactured with soy, milk, egg, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.

General Statements

This bottle is made from 100% PCR (post-consumer recycled) resin.

General health Family owned since 1968.

Seals/Symbols

Crescent H (Halal) GMP Quality Assured

Triangle K (Kosher)

FDA Statement of Identity

A Dietary Supplement

Storage

Store in a cool, dry place after opening.

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Brewer's Yeast 10 Grain, 650 mg by NOW label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Brewer's Yeast 10 Grain, 650 mg label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Brewer's Yeast 10 Grain, 650 mg by NOW

These are the 2 active ingredients this product is made of. Select any to open its full monograph.

Serving size3 Tablet(s) Dosage formTablet Or Pill Servings per container66 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Protein

1 Gram(s) per serving

Brewer's Yeast, Dried

Interacts with
136 drugs
1.95 Gram(s) per serving

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...

Brewer's Yeast, Dried monograph & interactions

Other (inactive) ingredients: Hydroxypropyl Cellulose, Stearic Acid, Croscarmellose Sodium, Magnesium Stearate, Silicon Dioxide. These complete the product’s ingredient list but are not active constituents.

Interaction report

Brewer's Yeast 10 Grain, 650 mg by NOW Drug Interactions

Want to check YOUR meds against Brewer's Yeast 10 Grain, 650 mg?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
136Drugs
9 Major 87 Moderate 40 Minor

Ingredients driving the most interactions

Brewer's Yeast, Dried 136

Individual Drug Interactions

The ingredients in Brewer's Yeast 10 Grain, 650 mg interact with 136 drugs. Click any drug to see the details.

1 of the 2 ingredients in Brewer's Yeast 10 Grain, 650 mg interact with drugs. Each result below shows which ingredient is responsible. Brewer's Yeast, Dried

Each ingredient & the kinds of drugs it affects

For each ingredient in Brewer's Yeast 10 Grain, 650 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Brewer's Yeast, Dried4 drug types · 136 drugs

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
Brewer's Yeast, Dried full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Brewer's Yeast 10 Grain, 650 mg, from the product label.

NOW

See all NOW products
Name
NOW FOODS
Street Address
395 S. Glen Ellyn Rd.
City
Bloomingdale
State
IL
ZipCode
60108
Web Address
nowfoods.com
Pharmacist Counseling Corner

Brewer's Yeast 10 Grain, 650 mg by NOW: Common Questions

Does Brewer's Yeast 10 Grain, 650 mg by NOW interact with any medications?
Yes. Based on its ingredients, Brewer's Yeast 10 Grain, 650 mg has a known interaction with 136 medications, including 9 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Brewer's Yeast 10 Grain, 650 mg contains 2 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
What's the difference between brewer's yeast and nutritional yeast?
We don't have that comparison in our data for this product. Both are yeast-based, but they're processed differently and their nutrient profiles differ — ask your pharmacist for specifics.
Will this give me gas?
Possibly. Flatulence is the most common side effect people report. Starting with a low dose and taking it with food may help, but talk with your pharmacist if it becomes bothersome.
Is brewer's yeast safe during pregnancy?
Food amounts are likely fine, but there isn't enough safety data on supplement doses during pregnancy. Check with your doctor or pharmacist for personalized advice before taking it.
Can I take this if I have a weak immune system?
The safety data raises a caution for people with weakened immune systems or certain conditions. Talk with your doctor before starting — they'll know your specific situation best.
Does brewer's yeast actually work for IBS?
The evidence says it's possibly effective for IBS, meaning there's some promising research, but it's not conclusive. Results vary by person — talk with your doctor about whether to try it.

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

Not sure if Brewer's Yeast 10 Grain, 650 mg is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Brewer's Yeast 10 Grain, 650 mg label
Go deeper

The Full Monographs Behind Brewer's Yeast 10 Grain, 650 mg’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Brewer's Yeast

Interacts with 136 drugs

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 cla...

Read the full Brewer's Yeast monograph →
Sources

Sources & How We Checked

Brewer's Yeast 10 Grain, 650 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 6 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Brewer's Yeast 6 references
  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. 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
  3. Bahijiri, S. M., Mira, S. A., Mufti, A. M., and Ajabnoor, M. A. The effects of inorganic chromium and brewer's yeast supplementation on glucose tolerance, serum lipids and drug dosage in individuals with type 2 diabetes. Saudi.Med.J. 2000;21(9):831-837. DOI
  4. Schrauzer, G. N. and de, Vroey E. Effects of nutritional lithium supplementation on mood. A placebo-controlled study with former drug users. Biol.Trace Elem.Res. 1994;40(1):89-101. PubMed
  5. Gayathri R, Aruna T, Malar S, Shilpa B, Dhanasekar KR. Efficacy of Saccharomyces cerevisiae CNCM I-3856 as an add-on therapy for irritable bowel syndrome. Int J Colorectal Dis. 2020;35(1):139-145. PubMed
  6. Mourey F, Decherf A, Jeanne JF, et al. Saccharomyces cerevisiae I-3856 in irritable bowel syndrome with predominant constipation. World J Gastroenterol 2022;28(22):2509-2522.

See these in context on the Brewer's Yeast monograph →

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

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