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Dietary supplement

B-1 100 mg Ingredients & Drug Interactions

by Nature's Truth

B-1 100 mg label
See full label image
Tablet Or Pill Category: Vitamin
Most serious interaction: Minor
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking B-1 100 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

B-1 100 mg is a dietary supplement by Nature's Truth 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 B-1 100 mg by Nature's Truth

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

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HelloPharmacist Scorecard of B-1 100 mg by Nature's Truth

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 (vitamin B-1) at 100 mg per tablet. Thiamine is an essential B vitamin your body needs to convert food into energy and support nerve and heart function.

The remaining ingredients — dicalcium phosphate, cellulose, croscarmellose, stearic acid, magnesium stearate, and silica — are inactive 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: Vitamin B supplement and thiamine support.
  • We looked for evidence on: Thiamine deficiency, Wernicke-Korsakoff syndrome (WKS), Energy metabolism, Nerve function.
  • 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).

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

For mosquito repellent and heart failure, the evidence doesn't support its use — it's rated possibly ineffective for both.

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 well tolerated by mouth in normal doses. Allergic reactions like skin rashes are rare, and serious reactions (anaphylaxis) only happen with injections, not tablets.

Thiamine is essential during pregnancy and breastfeeding — if you're pregnant or nursing, use this supplement only at the dose your doctor or midwife recommends.

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) or related medications, double-check with us before starting this product — it may raise thiamine levels in your blood. For all other medications, no interactions are documented for the thiamine we could check.

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 supplement is a good choice if you have a thiamine deficiency or need to support your B-1 intake. If you take trimethoprim or similar antibiotics, check with us first.

For pregnancy or breastfeeding, chat with your provider about the right dose for you.

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 Mar 22, 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 B-1 100 mg, straight from the product label.

Brand Nature's Truth
Barcode (UPC) 840093105882
Net contents 100 Tablet(s)
Market status On market
Date entered into DSLD Mar 22, 2024
DSLD ID 306625
Product type Vitamin
Supplement form Tablet Or Pill
Dietary claims / uses Nutrient, All Other
Intended target group(s) Vegetarian, 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 B-1 100 mg by Nature's Truth, 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
100
UPC/BARCODE
840093105882
IngredientAmount% DV
Thiamine100 mg8333%

Other ingredients: Dicalcium Phosphate, Cellulose, Croscarmellose, Stearic Acid, Magnesium Stearate, Silica

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.
Seals/Symbols

100% Quality Satisfaction Guarantee

Our Non-GMO Pledge Visit our website

General Statements

Vitamins

Formulation

Gluten free Non GMO

Vegetarian friendly

No gluten, wheat, yeast, milk, lactose, soy, artificial color, artificial flavor, artificial sweetener, preservatives. Non-GMO

Vegetarian formula

FDA Statement of Identity

Vitamin Supplement

Formula

B-vitamin

Suggested/Recommended/Usage/Directions

Directions: For adults, take one (1) tablet two times daily, preferably with meals.

Precautions

Warning: If you are pregnant, nursing, taking any medications or have any medical condition, consult your doctor before use.

If any adverse reactions occur, immediately stop using this product and consult your doctor. If seal under cap is damaged or missing, do not use.

Keep out of reach of children.

Storage

Store in a cool, dry place.

Brand IP Statement(s)

Copyright 2021 Nature's Truth LLC

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

See for yourself

B-1 100 mg by Nature's Truth label

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

B-1 100 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 B-1 100 mg by Nature's Truth

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 container100 Amounts shown are per serving.

Thiamine

Interacts with
3 drugs
100 mg per serving Form: Thiamine Hydrochloride, Vitamin B1

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: Dicalcium Phosphate, Cellulose, Croscarmellose, Stearic Acid, Magnesium Stearate, Silica. These complete the product’s ingredient list but are not active constituents.

Interaction report

B-1 100 mg by Nature's Truth Drug Interactions

Want to check YOUR meds against B-1 100 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

Thiamine 3

Individual Drug Interactions

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

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

Each ingredient & the kinds of drugs it affects

For each ingredient in B-1 100 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.

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 B-1 100 mg, from the product label.

Nature's Truth

See all Nature's Truth products
Name
Nature's Truth LLC
City
Ronkonkoma
State
NY
ZipCode
11779
Phone Number
1-844-544-1030
Web Address
naturestruthproducts.com
Pharmacist Counseling Corner

B-1 100 mg by Nature's Truth: Common Questions

Does B-1 100 mg by Nature's Truth interact with any medications?
Yes. Based on its ingredients, B-1 100 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?
B-1 100 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 help with energy and fatigue?
If your fatigue is caused by a thiamine deficiency, this supplement will help restore normal energy. If your fatigue has another cause — stress, poor sleep, or other nutrient gaps — you'd need to address that instead. That's a question for your doctor.
Is it safe to take if I'm pregnant or breastfeeding?
Thiamine is essential during pregnancy and breastfeeding, but use only the dose your doctor or midwife advises. Don't guess on the amount — talk with your provider about what's right for you.
What exactly is thiamine?
Thiamine is vitamin B-1, a nutrient your body needs to turn food into energy and keep your nerves and heart working well. Your body can't store it, so you need it regularly from food or supplements.
Can it cause allergic reactions?
Allergic skin reactions are very rare when you take thiamine by mouth. Serious reactions only happen with injections, not tablets.

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

Not sure if B-1 100 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.

B-1 100 mg label
Go deeper

The Full Monographs Behind B-1 100 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

B-1 100 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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