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Dietary supplement

Vitamin B-1 100 mg High Potency Thiamin HCl Ingredients & Drug Interactions

by Nature's Way

Vitamin B-1 100 mg High Potency Thiamin HCl label
See full label image
Capsule Category: Vitamin
Most serious interaction: Minor
Clinical methodology reviewed by · Updated Sep 30, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Vitamin B-1 100 mg High Potency Thiamin HCl 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-1 100 mg High Potency Thiamin HCl is a dietary supplement by Nature's Way 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 Thiamine. 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-1 100 mg High Potency Thiamin HCl by Nature's Way

Ask about any prescription or over-the-counter medication and we check it for interactions with Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way — and tell you which ingredient is responsible.

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HelloPharmacist Scorecard of Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way

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: thiamine (also called vitamin B-1), supplied as thiamine hydrochloride at 100 mg per capsule. Thiamine is an essential B vitamin your body needs to turn food into energy and keep your nerves and heart working properly.

The capsule also contains inactive ingredients—cellulose, gelatin, and magnesium stearate—which are common binders and fillers.

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: supports energy metabolism and carbohydrate conversion.
  • We looked for evidence on: Thiamine deficiency, Wernicke-Korsakoff syndrome (WKS), Fatigue, beriberi, energy production.
  • 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 Fatigue.

Thiamine is effective for treating thiamine deficiency and Wernicke-Korsakoff syndrome (a serious neurological condition linked to severe thiamine lack, often seen in heavy alcohol use). It's possibly effective for period pain (dysmenorrhea).

The evidence for heart failure and mosquito repellent is possibly ineffective. If you're taking this to correct a known deficiency or that specific condition, it can help; for other uses, the science doesn't yet support a clear benefit.

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.

Thiamine is generally very safe when taken by mouth in normal doses. Allergic reactions—like skin rashes—are rare, and serious reactions are very uncommon.

During pregnancy and breastfeeding, thiamine is actually needed for your baby's development. If you're pregnant or nursing and want to take a supplement, talk with your doctor or midwife first so they can make sure the dose is right for you.

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 (Proloprim), mention this supplement to your pharmacist—it's a minor interaction, but worth flagging. No other major or moderate interactions are documented for this ingredient.

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 have a documented thiamine deficiency or Wernicke-Korsakoff syndrome. If you take trimethoprim (an antibiotic), let your pharmacist know you're using it.

For other uses, evidence is limited. Talk to your pharmacist before starting, especially if you're pregnant or breastfeeding.

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 Jul 24, 2025.

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-1 100 mg High Potency Thiamin HCl, straight from the product label.

Brand Nature's Way
Barcode (UPC) 033674404119
Net contents 100 Capsule(s)
Market status On market
Date entered into DSLD Jul 24, 2025
DSLD ID 333776
Product type Vitamin
Supplement form Capsule
Dietary claims / uses Nutrient, All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free, 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 Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way, 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 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
Servings per container
100
UPC/BARCODE
033674404119
IngredientAmount% DV
Thiamine100 mg8333%

Other ingredients: Cellulose, Gelatin, Magnesium Stearate

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.
Formulation

Supports energy metabolism Helps convert food to fuel Made with the quality you trust

Bottled and tested in the USA

Supports energy metabolism

Gluten free. No wheat, corn, soy, dairy, or artificial colors or flavors.

Formula

Vitamin B-1 100 mg High Potency Thiamin HCl With 100 mg thiamin (vitamin B1) per serving Essential coenzyme involved in carbohydrate metabolism

Vitamin B-1 High Potency Thiamin HCl 100 mg per serving

General Statements

Explore more products at NATURESWAY.COM Bottle made from 50% post-consumer recycled plastic

Brand IP Statement(s)

Copyright 2024 Nature’s Way Brands, LLC

FDA Disclaimer Statement

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

FDA Statement of Identity

Dietary Supplement

Suggested/Recommended/Usage/Directions

Recommendation: Adults take 1 capsule daily, preferably with food.

Precautions

If you are pregnant, nursing, or taking any medications, consult a healthcare professional before use.

Keep out of reach of children.

Safety sealed with inner seal. Do not use if seal is broken or missing.

Storage

Store at room temperature. Avoid excessive heat and direct sunlight.

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

See for yourself

Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way label

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

Vitamin B-1 100 mg High Potency Thiamin HCl 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-1 100 mg High Potency Thiamin HCl by Nature's Way

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

Serving size1 Capsule(s) Dosage formCapsule Servings per container100 Amounts shown are per serving.

Thiamine

Interacts with
3 drugs
100 mg per serving Form: Thiamine Hydrochloride

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...

Thiamine monograph & interactions

Other (inactive) ingredients: Cellulose, Gelatin, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way Drug Interactions

Want to check YOUR meds against Vitamin B-1 100 mg High Potency Thiamin HCl?

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

Thiamine 3

Individual Drug Interactions

The ingredients in Vitamin B-1 100 mg High Potency Thiamin HCl interact with 3 drugs. Click any drug to see the details.

1 of the 1 ingredient in Vitamin B-1 100 mg High Potency Thiamin HCl interact with drugs. Each result below shows which ingredient is responsible. Thiamine

Each ingredient & the kinds of drugs it affects

For each ingredient in Vitamin B-1 100 mg High Potency Thiamin HCl 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.

Thiamine1 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
Thiamine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Vitamin B-1 100 mg High Potency Thiamin HCl, from the product label.

Nature's Way

See all Nature's Way products
Name
Nature's Way Brands, LLC
City
Green Bay
State
WI
ZipCode
54311
Phone Number
1-800-962-8873
Web Address
naturesway.com
Pharmacist Counseling Corner

Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way: Common Questions

Does Vitamin B-1 100 mg High Potency Thiamin HCl by Nature's Way interact with any medications?
Yes. Based on its ingredients, Vitamin B-1 100 mg High Potency Thiamin HCl 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-1 100 mg High Potency Thiamin HCl 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.
Is this safe to take while I'm pregnant?
Thiamine is needed during pregnancy, and this supplement is rated Likely Safe. However, use it only at the dose your doctor or midwife recommends for you—don't guess at the right amount on your own.
Can I take this if I'm breastfeeding?
Yes, thiamine is needed while breastfeeding. Use the supplement at recommended amounts and let your provider know you're taking it so they can confirm the dose is appropriate for you and your baby.
Does thiamine actually help prevent mosquito bites?
The evidence doesn't support that. Thiamine is possibly ineffective as a mosquito repellent, so don't count on it for that purpose.
What are the side effects?
Thiamine taken by mouth is very well tolerated. Allergic reactions like skin rashes are rare. If you get an injection of thiamine (not the case with this oral capsule), serious reactions are also uncommon but possible.
Is this the right product if I have low B-1?
If you have a confirmed thiamine deficiency, yes—this product is effective for that. But have your doctor confirm the deficiency first and advise you on the right dose for your situation.

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

Not sure if Vitamin B-1 100 mg High Potency Thiamin HCl is safe with your meds?

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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-1 100 mg High Potency Thiamin HCl label
Go deeper

The Full Monographs Behind Vitamin B-1 100 mg High Potency Thiamin HCl’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-1 100 mg High Potency Thiamin HCl'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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