Drug & supplement interaction

Thiamine + Semaglutide

Semaglutide brand names: Ozempic, Rybelsus, Wegovy.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Thiamine and Semaglutide in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Thiamine and Semaglutide

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Semaglutide and Thiamine in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Thiamine safety at a glance

Thiamine overall Generally safe Thiamine is generally very safe when taken by mouth in normal amounts.
Pregnancy Likely Safe When used orally in dietary amounts of 1.4 mg daily. A tolerable upper intake level (UL) has not been established for healthy individuals. Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in dietary amounts of 1.4 mg daily. A tolerable upper intake level (UL) has not been established for healthy individuals. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Semaglutide and Thiamine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Semaglutide

Interactions in our licensed database are recorded against drug classes, not just single drug names. Semaglutide is filed under 2 classifications — antidiabetes drugs, oral drugs. Thiamine has documented interactions with 1 drug class — the most serious being trimethoprim (proloprim) (minor) — and none of Semaglutide’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Thiamine Does Interact With Other Medications

Thiamine has 3 minor known drug interactions in our database — Semaglutide isn’t one of them. If you take anything else, check it against the full list below.

Taking anything else?

Check Another of Your Medications Against Thiamine

Covers the 2,830 medications we’ve checked against Thiamine. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Thiamine and Semaglutide May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • An allergic reaction Worth acting on Additional detail

    Thiamine

    “Orally, thiamine might rarely cause dermatitis and other allergic reactions. Parenterally, thiamine can cause anaphylactoid and hypersensitivity reactions, but this is also rare (”

    Thiamine · Natural Medicines adverse-effect record, reported in acute respiratory distress syndrome (ards).

    4 sources cited
    1. 15. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
    2. 35585. 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
    3. 105445. Thiamine hydrochloride injection package insert. Lake Zurich, IL: Fresenius Kabi, LLC; September 2019.
    4. 91170. 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

    Semaglutide

    Listed in the ADVERSE REACTIONS section of the FDA label for Semaglutide. Read the label on DailyMed ›

Reported for Thiamine but not commonly for Semaglutide: bleeding in the gut, shortness of breath, low blood pressure and a skin rash.

Effects for Semaglutide come from the ADVERSE REACTIONS section of its FDA label; effects for Thiamine come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Thiamine in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally in dietary amounts of 1.4 mg daily. A tolerable upper intake level (UL) has not been established for healthy individuals.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Semaglutide Is Prescribed For, and What Thiamine Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Semaglutide is a prescription medicine with approved uses on its FDA label. Thiamine is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Semaglutide is prescribed for: Semaglutide is available as Wegovy (injection and tablet) and Ozempic (injection), and each product has its own approved uses. Wegovy injection is approved — alongside diet and exercise — to reduce excess body weight in adults and in children aged 12 and older with obesity, to lower the risk of serious heart events (heart attack, stroke, or cardiovascular death) in adults with obesity or overweight who also have established heart disease, and for treatment of a liver condition called MASH (metabolic dysfunction-associated steatohepatitis, formerly called NASH) with moderate-to-advanced scarring in adults. Wegovy tablets share the cardiovascular risk reduction and weight management uses in adults, but are not approved for MASH or for use in children. Ozempic injection is approved to improve blood sugar control in adults with type 2 diabetes (alongside diet and exercise) and to reduce the risk of major cardiovascular events in adults with type 2 diabetes who also have established heart disease.

Read the rest of what Semaglutide is prescribed for

All forms are used alongside a reduced-calorie diet and increased physical activity. Ozempic is not approved for type 1 diabetes. The MASH approval for Wegovy injection is an accelerated approval, meaning continued approval may depend on results from a confirmatory study.

Thiamine has been studied for:

  • Kidney failure studied, not established Thiamine has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Thiamine for kidney failure

    Oral thiamine has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

  • Diabetes studied, not established Thiamine has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Thiamine for diabetes

    It is unclear if oral thiamine is beneficial for type 2 diabetes or gestational diabetes.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Semaglutide on your own; if you are taking Thiamine for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Thiamine or Semaglutide

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Thiamine or Semaglutide, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Semaglutide

This page covers Thiamine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Semaglutide page lists 256 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate) and Agaricus Mushroom (moderate).

By severity: 2 major · 215 moderate · 39 minor.

From our pharmacist’s overview on the Semaglutide page

“Semaglutide (Ozempic, Rybelsus, Wegovy) lowers blood sugar, and so do most of the 256 supplements on this page, which is why I read this list with real vigilance rather than a shrug. Nearly all of the entries either add to its glucose-lowering effect and raise the risk of hypoglycemia, or push sugar the other way and blunt it, as niaci…”

Reviewed by 2 · Jul 18, 2026

Open the Semaglutide interaction page

One more smart check

Taking Thiamine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3 real supplement products containing Thiamine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Thiamine. Even though Thiamine itself has no known interaction with Semaglutide, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Thiamine and Semaglutide Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Thiamine
Top 25%

#175 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Semaglutide
Top 1%

#24 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Thiamine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Thiamine and Semaglutide records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Thiamine

What is Thiamine?

  • Preventing or treating thiamine deficiency
  • Beriberi
  • Wernicke-Korsakoff syndrome (alcohol-related)
  • Supporting energy and nerve function
  • General B-vitamin supplementation

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 clearly useful for deficiency, certain medical conditions, and people with heavy alcohol use. Talk with your pharmacist or doctor before starting it, especially if you have a chronic illness.

Tablets, capsules, oral liquids, injectable solutions (prescription), part of B-complex and multivitamins

An interaction check asks whether these two react with each other — it does not ask whether Thiamine is a good idea for someone in your situation. Here is what our Thiamine record says about it on its own.

Thiamine: dosing

The right dose of thiamine depends on your age, health, and the reason you are taking it. There is a recommended daily intake for general nutrition, and higher amounts are sometimes used by doctors to treat a deficiency.For supplements, the best approach is to follow the directions on the product label and not exceed them without guidance.

From our Thiamine monograph — the full record covers uses, side effects and every documented interaction.

Read the full Thiamine monograph & all interactions
Medication

About Semaglutide

What Is Semaglutide Used For?

Brand names: Ozempic, Rybelsus, Wegovy

Semaglutide is available as Wegovy (injection and tablet) and Ozempic (injection), and each product has its own approved uses. Wegovy injection is approved — alongside diet and exercise — to reduce excess body weight in adults and in children aged 12 and older with obesity, to lower the risk of serious heart events (heart attack, stroke, or cardiovascular death) in adults with obesity or overweight who also have established heart disease, and for treatment of a liver condition called MASH (metabolic dysfunction-associated steatohepatitis, formerly called NASH) with moderate-to-advanced scarring in adults. Wegovy tablets share the cardiovascular risk reduction and weight management uses in adults, but are not approved for MASH or for use in children. Ozempic injection is approved to improve blood sugar control in adults with type 2 diabetes (alongside diet and exercise) and to reduce the risk of major cardiovascular events in adults with type 2 diabetes who also have established heart disease.

All forms are used alongside a reduced-calorie diet and increased physical activity. Ozempic is not approved for type 1 diabetes. The MASH approval for Wegovy injection is an accelerated approval, meaning continued approval may depend on results from a confirmatory study.

See full Semaglutide drug information
Keep checking

Other Drugs & Thiamine

Browse every other medication we’ve checked against Thiamine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
3Minor
2,826No known interaction
Minor

3 interactions

No interaction 2,826 drugs checked — show the list
Evidence & sources

Thiamine References

The 7 references that drive our Thiamine monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  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.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Thiamine and Semaglutide Together: Common Questions

Is it safe to take Thiamine with Semaglutide?
We do not list a known interaction between Thiamine and Semaglutide. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Thiamine and Semaglutide have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Thiamine and Semaglutide used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Thiamine in each. That is a conversation for your prescriber, especially if Semaglutide is being adjusted to a target.
How was the Thiamine and Semaglutide combination checked?
Interactions in our licensed database are recorded against drug classes. Semaglutide is filed under 2 classifications, and Thiamine has documented interactions with 1 drug class — none of Semaglutide's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Thiamine interact with any other medications?
Yes. Thiamine has 3 documented drug interactions in our database — Semaglutide is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Semaglutide interact with any supplements?
Yes. Semaglutide has documented interactions with 256 supplements in our database — Thiamine is not one of them. The Semaglutide interaction page linked on this page lists every one, ranked by severity.

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

Still Have a Question About Semaglutide and Thiamine?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.