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Dietary supplement

Vitamin B-1 500 mg Ingredients & Drug Interactions

by Best Naturals

Vitamin B-1 500 mg label
See full label image
Tablet Or Pill Category: Vitamin
Most serious interaction: Minor
Clinical methodology reviewed by · Updated Sep 23, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Vitamin B-1 500 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: Minor

Vitamin B-1 500 mg is a dietary supplement by Best Naturals with 1 active ingredient. Its ingredients are commonly taken for preventing or treating thiamine deficiency, beriberi, wernicke-korsakoff syndrome (alcohol-related).Based on those ingredients, 3 medications have a known interaction with it, the most serious rated minor. The ingredients most likely to interact are Vitamin B1. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Vitamin B-1 500 mg by Best Naturals

Ask about any prescription or over-the-counter medication and we check it for interactions with Vitamin B-1 500 mg by Best Naturals — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Vitamin B-1 500 mg by Best Naturals

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 Jul 11, 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: Vitamin B1 (thiamine), a water-soluble B vitamin your body needs to turn food into energy and keep your nerves working properly. Each tablet delivers 500 mg.

The inactive ingredients are dicalcium phosphate, microcrystalline cellulose, stearic acid, croscarmellose sodium, silicon dioxide, magnesium stearate, and pharmaceutical glaze — these are fillers and binders that hold the tablet together.

Does it work?

Strong 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
Strong

Clinical evidence supports at least one of this product's ingredients for its stated purpose.

Why this rating?
  • The label markets this product for: support energy production and healthy nervous system.
  • We looked for evidence on: Thiamine deficiency, Wernicke-Korsakoff syndrome (WKS), Fatigue, Cognitive function, Diabetic neuropathy, Beriberi — and 2 related terms.
  • The strongest evidence on file: Thiamine is rated "Effective" for Thiamine deficiency (Natural Medicines).
  • Also on file: Thiamine is rated "Effective" for Wernicke-Korsakoff syndrome (WKS).
  • Also on file: Thiamine is rated "Insufficient Reliable Evidence To Rate" for Cognitive function, Diabetic neuropathy, Fatigue.

Thiamine is effective for treating thiamine deficiency and Wernicke-Korsakoff syndrome (a serious neurological condition caused by severe B-1 shortage). It's possibly effective for dysmenorrhea (painful periods).

The evidence doesn't support it as a mosquito repellent or for heart failure, where it's rated possibly ineffective.

The evidence, ingredient by ingredient Thiamine

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.

Vitamin B-1 is generally very well tolerated by mouth at normal doses. Rarely, people may experience allergic reactions like dermatitis (skin irritation).

Thiamine is needed during pregnancy and breastfeeding — the data rates it likely safe in these settings — but use supplement doses only as your doctor or midwife advises, not on your own.

Side effects, ingredient by ingredient Thiamine

Meds to double-check

Minor interactions only
Known Interaction Concern · database check
Minor only

Only Minor-severity interactions are documented for these ingredients.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Thiamine.
  • The most serious interaction on file is rated Minor.
  • For scale: 3 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.

If you take trimethoprim (an antibiotic), mention this B-1 supplement to your pharmacist — it may raise your thiamine blood level slightly. No other interactions are documented for the ingredients we hold data on.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Only minor medication interactions are documented, and safety information is well characterized.

This is a straightforward B-1 supplement useful if you're deficient in thiamine or recovering from Wernicke-Korsakoff syndrome. If you take trimethoprim (an antibiotic), check with your pharmacist first.

It's safe for pregnancy and breastfeeding under provider guidance.

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 Jun 16, 2022.

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 Vitamin B-1 500 mg, straight from the product label.

Brand Best Naturals
Barcode (UPC) 817716018522
Net contents 120 Tablet(s)
Market status On market
Date entered into DSLD Jun 16, 2022
DSLD ID 270860
Product type Vitamin
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, Sugar 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 Vitamin B-1 500 mg by Best Naturals, 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:
1 Tablet(s)
Maximum serving Sizes:
1 Tablet(s)
Servings per container
120
UPC/BARCODE
817716018522
IngredientAmount% DV
Vitamin B1500 mg41667%

Other ingredients: Dicalcium Phosphate, Microcrystalline Cellulose, Stearic Acid, Croscarmellose Sodium, Silicon Dioxide, Magnesium Stearate, Pharmaceutical Glaze

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.
Formula

Certain research publications indicate that Vitamin B1 (Thiamine Mononitrate) may help support the following: Support energy production. Supports healthy nervous system.

(Thiamine Mononitrate)

Suggested/Recommended/Usage/Directions

Suggested Use: As a dietary supplement, take one (1) tablet one to two times daily, preferably with meals, or as directed by your qualified healthcare professional.

Precautions

Keep out of the reach of children.

Do not use if safety seal is broken or missing.

Caution: For adults only, if you are pregnant, nursing, taking any medications or have any medical condition, consult your doctor before use.

Caution: For adults only, if you are pregnant, nursing, taking any medications or have any medical condition, consult your doctor before use. Discontinue use and consult your doctor if any adverse reactions occur.

Storage

Keep in cool, dry place.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Seals/Symbols

Made in USA

GMP Good Manufacturing Practice Product

Formulation

Premium formula

3rd party lab tested

No artificial color, flavor or sweetener, no preservatives, no sugar, no starch, no corn, no soy, no egg, no lactose, no gluten, no wheat, no yeast, no fish.

FDA Statement of Identity

Dietary Supplement

General Statements

For additional information call 1-877-659-6004

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

See for yourself

Vitamin B-1 500 mg by Best Naturals label

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

Vitamin B-1 500 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 Vitamin B-1 500 mg by Best Naturals

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size1 Tablet(s) Dosage formTablet Or Pill Servings per container120 Amounts shown are per serving.

Vitamin B1

Interacts with
3 drugs
500 mg per serving Form: Thiamine Mononitrate

Thiamine (vitamin B1) is an essential nutrient your body needs to turn food into energy and to keep your nerves and heart healthy. Most people get eno...

Vitamin B1 monograph & interactions

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

Interaction report

Vitamin B-1 500 mg by Best Naturals Drug Interactions

Want to check YOUR meds against Vitamin B-1 500 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
3Drugs
3 Minor

Ingredients driving the most interactions

Vitamin B1 3

Individual Drug Interactions

The ingredients in Vitamin B-1 500 mg interact with 3 drugs. Click any drug to see the details.

1 of the 1 ingredient in Vitamin B-1 500 mg interact with drugs. Each result below shows which ingredient is responsible. Vitamin B1

Each ingredient & the kinds of drugs it affects

For each ingredient in Vitamin B-1 500 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.

Vitamin B11 drug type · 3 drugs

Trimethoprim (Proloprim)

Trimethoprim might increase blood levels of thiamine.
In vitro, animal, and clinical research suggest that trimethoprim inhibits intestinal thiamine transporter ThTR-2, hepatic transporter OCT1, and renal transporters OCT2, MATE1, and MATE2, resulting in paradoxically increased thiamine plasma concentrations.

Likelihood Probable Evidence B
Vitamin B1 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Vitamin B-1 500 mg, from the product label.

Best Naturals

See all Best Naturals products
Name
Best Naturals
Street Address
PO Box 394
City
Kenilworth
State
NJ
ZipCode
07033
Phone Number
1-877-659-6004
Web Address
www.shopbestnaturals.com
Pharmacist Counseling Corner

Vitamin B-1 500 mg by Best Naturals: Common Questions

Does Vitamin B-1 500 mg by Best Naturals interact with any medications?
Yes. Based on its ingredients, Vitamin B-1 500 mg has a known interaction with 3 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Vitamin B-1 500 mg contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism 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.
Will this B-1 supplement work for my deficiency?
Yes. Vitamin B-1 is effective for treating thiamine deficiency, so it should help if that's been confirmed as your diagnosis. Work with your doctor on the right dose and length of treatment for your situation.
Is it okay to take during pregnancy?
Thiamine is needed in pregnancy and rated likely safe as a supplement. But use it only at the dose your doctor or midwife recommends — don't self-dose higher amounts without checking with them first.
What are the side effects?
Thiamine taken by mouth is very well tolerated. Rarely, people have had allergic reactions like skin irritation. Serious reactions are extremely rare.
Can I take this if I'm breastfeeding?
Thiamine is needed while you're breastfeeding and is likely safe in supplements. Use it at the recommended amount and let your provider know you're taking it.
Does this help with period pain?
There's some evidence that thiamine may help with dysmenorrhea (painful periods) — it's rated possibly effective. Whether it helps you is individual, so talk to your doctor about whether to try it.

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

Not sure if Vitamin B-1 500 mg is safe with your meds?

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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.

Vitamin B-1 500 mg label
Go deeper

The Full Monographs Behind Vitamin B-1 500 mg’s Ingredients

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

Herb & supplement monograph

Thiamine

Interacts with 3 drugs

Thiamine (vitamin B1) is an essential nutrient your body needs to turn food into energy and to keep your nerves and heart healthy. Most people get enough from food, but supplements are clear...

Read the full Thiamine monograph →
Sources

Sources & How We Checked

Vitamin B-1 500 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 7 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.

Thiamine 7 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Yates AA, Schlicker SA, Suitor CW. Dietary reference intakes: The new basis for recommendations for calcium and related nutrients, B vitamins, and choline. J Am Diet Assoc 1998;98:699-706. PubMed
  3. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. Available at: http://b
  4. Rogovik, A. L., Vohra, S., and Goldman, R. D. Safety considerations and potential interactions of vitamins: should vitamins be considered drugs? Ann.Pharmacother. 2010;44(2):311-324. PubMed
  5. Arruti N, Bernedo N, Audicana MT, Villarreal O, Uriel O, Muñoz D. Systemic allergic dermatitis caused by thiamine after iontophoresis. Contact Dermatitis. 2013 Dec;69(6):375-6. PubMed
  6. Thiamine hydrochloride injection package insert. Lake Zurich, IL: Fresenius Kabi, LLC; September 2019.
  7. Vora B, Wen A, Yee SW, et al. The Effect of Trimethoprim on Thiamine Absorption: A Transporter-Mediated Drug-Nutrient Interaction. Clin Pharmacol Ther 2023;114(2):381-392.

See these in context on the Thiamine 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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