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Dietary supplement

Vitamin B-1 Ingredients & Drug Interactions

by Solaray

Vitamin B-1 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 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 is a dietary supplement by Solaray 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 by Solaray

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

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HelloPharmacist Scorecard of Vitamin B-1 by Solaray

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 Sep 24, 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), an essential B vitamin your body needs to convert food into energy and support nerve function. The capsule also contains inactive ingredients — a whole food base, gelatin capsule material, and magnesium stearate (a flow agent).

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: energy and nerve function support.
  • We looked for evidence on: Thiamine deficiency, Wernicke-Korsakoff syndrome (WKS), Fatigue, Beriberi, nerve health.
  • 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 caused by severe thiamine lack). It's also possibly effective for dysmenorrhea (painful periods).

For mosquito repellent and heart failure, the evidence we hold suggests it's 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.

Thiamine is generally very well tolerated when taken by mouth at normal doses. Allergic reactions like dermatitis are rare; if you receive thiamine by injection, very rare anaphylactoid or hypersensitivity reactions are possible, but these are uncommon.

Thiamine is needed during pregnancy and breastfeeding — use supplement doses only as your doctor or midwife advises, not megadoses 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 (Proloprim), let your doctor or pharmacist know before starting this B-1 supplement — it may raise your thiamine blood levels slightly. No other interactions are documented in our data for the ingredients 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.

If you have a thiamine deficiency or Wernicke-Korsakoff syndrome, this supplement is an effective option. If you take trimethoprim or other medications, check them against the tool on this page before starting.

Talk with your doctor or pharmacist about whether B-1 is right for you and what dose fits your situation.

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 Oct 1, 2012.

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, straight from the product label.

Brand Solaray
Net contents 100 Capsule(s)
Market status On market
Date entered into DSLD Oct 1, 2012
DSLD ID 13390
Product type Vitamin
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
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 by Solaray, 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
IngredientAmount% DV
Thiamine100 mg6667%

Other ingredients: Whole Food Base, Gelatin Capsule, 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.
Suggested/Recommended/Usage/Directions

Directions: Use only as directed. Take one capsule daily, with a meal or glass of water.

Storage

Store in a cool, dry place.

General Statements

Call.

Description: Vitamin B-1, also known as Thiamine, plays an important role in human biochemistry. It is transformed into a coenzyme essential for the body to convert food chemicals to ATP, an energy form that the body can use.

Product # 4325

Size: 100ct 100mg

Brand IP Statement(s)

All rights reserved.

The Promise of the Rainbow(TM)

Copyright and Disclaimer 1997-2011 Nutraceutical Corporation

FDA Statement of Identity

DIETARY SUPPLEMENT

Formula

B1 - 100mg

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

See for yourself

Vitamin B-1 by Solaray label

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

Vitamin B-1 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 by Solaray

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 Mononitrate, 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: Whole Food Base, Gelatin Capsule, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Vitamin B-1 by Solaray Drug Interactions

Want to check YOUR meds against Vitamin B-1?

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 interact with 3 drugs. Click any drug to see the details.

1 of the 1 ingredient in Vitamin B-1 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 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, from the product label.

Solaray

See all Solaray products
Name
Nutraceutical Corporation
Street Address
1400 Kearns Blvd., Second Floor
City
Park City
State
UT
ZipCode
84060
Pharmacist Counseling Corner

Vitamin B-1 by Solaray: Common Questions

Does Vitamin B-1 by Solaray interact with any medications?
Yes. Based on its ingredients, Vitamin B-1 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 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 my energy levels?
Thiamine does help your body convert food into energy, so it's effective if you have a deficiency. If your energy is low because you lack B-1, supplementing will help — but if your levels are already normal, extra thiamine won't boost energy further. Your doctor can check whether you're deficient.
Can I take this while pregnant?
Thiamine is needed during pregnancy, and it's rated as likely safe in supplement form. Take it only at the dose your doctor or midwife recommends — don't self-dose at high levels. Talk with them about whether you need a B-1 supplement.
Are there side effects?
Thiamine taken by mouth rarely causes allergic reactions like dermatitis. It's very safe at normal doses. If you get thiamine by injection, very rare hypersensitivity reactions are possible, but this is uncommon.
What is thiamine used for?
Thiamine (vitamin B-1) is essential for converting food into energy and supporting your nervous system. It's effective for treating thiamine deficiency and a serious neurological condition called Wernicke-Korsakoff syndrome.
Is this safe while breastfeeding?
Thiamine is needed while breastfeeding and is rated as likely safe. Use it at the dose your doctor recommends, not at high levels on your own.

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

Not sure if Vitamin B-1 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 label
Go deeper

The Full Monographs Behind Vitamin B-1’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'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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