Drug & supplement interaction

Glucosamine + Levothyroxine

Levothyroxine brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, and others.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Glucosamine and Levothyroxine 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 label for Levothyroxine states a food rule worth keeping to, and 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

Glucosamine and Levothyroxine

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 Levothyroxine and Glucosamine 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.

Glucosamine safety at a glance

Glucosamine overall Use caution Generally well tolerated by most adults, but quality and benefit vary and certain people should be careful.

Pregnancy Avoid There is not enough safety information, so it is best to avoid during pregnancy.

Breastfeeding Avoid Not enough is known about safety while breastfeeding, so avoid unless your doctor advises otherwise.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Levothyroxine and Glucosamine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Levothyroxine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine is filed under 3 classifications — including thyroid hormone, oral drugs. Glucosamine has documented interactions with 4 drug classes — the most serious being warfarin (coumadin) (major), topoisomerase ii inhibitors (moderate) and acetaminophen (tylenol, others) (minor) — and none of Levothyroxine’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

Glucosamine Does Interact With Other Medications

Glucosamine has 2 major, 13 moderate, 155 minor known drug interactions in our database — Levothyroxine isn’t one of them. If you take anything else, check it against the full list below.

Major 2 Moderate 13 Minor 155 No known interaction 2,660 (incl. Levothyroxine)

Taking anything else?

Check Another of Your Medications Against Glucosamine

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

What to actually watch for

No Interaction Found — But Data Suggests Glucosamine and Levothyroxine May Share Several of the Same Side Effects

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. 5 of them are worth acting on rather than waiting out — marked below.

Wheezing Worth acting on Additional detail
Glucosamine
“Cases of asthma exacerbations associated with the use of glucosamine (form unknown)-chondroitin products have been reported.”

Glucosamine · Natural Medicines adverse-effect record, reported in asthma.
1 source cited

10002. Tallia AF, Cardone DA. Asthma exacerbation associated with glucosamine-chondroitin supplement. J Am Board Fam Pract 2002;15:481-4..
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Shortness of breath / A severe allergic reaction / Hives Worth acting on Additional detail
Glucosamine
“There is some concern that glucosamine products might cause allergic reactions in sensitive individuals. One review of glucosamine-related adverse events in Australia found that 72% of all reports involved hypersensitivity reactions.”

Glucosamine · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).
2 sources cited

102115. Hoban C, Byard R, Musgrave I. Hypersensitive adverse drug reactions to glucosamine and chondroitin preparations in Australia between 2000 and 2011. Postgrad Med J. 2019 Oct 9. pii: postgradmedj-2019-136957. PubMed

89516. Hochberg MC, Martel-Pelletier J, Monfort J, Möller I, Castillo JR, Arden N,Berenbaum F, Blanco FJ, Conaghan PG, Doménech G, Henrotin Y, Pap T, Richette P, Sawitzke A, du Souich P, Pelletier JP; on behalf of the MOVES Investigation Group. Combined chondroi
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
An allergic reaction Worth acting on Additional detail

Glucosamine

“Orally, all forms of glucosamine seem to be well tolerated. Topically and rectally, N-acetyl glucosamine also seems to be well tolerated. Intramuscularly, glucosamine sulfate seems to be well tolerated.”

Glucosamine · Natural Medicines adverse-effect record, reported in constipation.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Itching Additional detail
Glucosamine
“Orally, glucosamine might cause skin reactions, including itching, rash, and erythema. Also, fingernail and toenail toughening, with an increased rate of growth, has been reported. Topically, N-acetyl glucosamine 2% with niacinamide 4% cream might cause rare skin reactions.”

Glucosamine · Natural Medicines adverse-effect record, reported in erythema.
6 sources cited

2608. Barclay TS, Tsourounis C, McCart GM. Glucosamine. Ann Pharmacother 1998;32:574-9.

20084. Giordano N, Fioravanti A, Papakostas P, et al. The efficacy and tolerability of glucosamine sulfate in the treatment of knee osteoarthritis: a randomized, double-blind, placebo-controlled trial. Curr Ther Res Clin Exp 2009;70(3):185-196. PubMed

89567. Wangroongsub Y, Tanavalee A, Wilairatana V, Ngarmukos S. Comparable clinical outcomes between glucosamine sulfate-potassium chloride and glucosamine sulfate sodium chloride in patients with mild and moderate knee osteoarthritis: a randomized, double-blind

110628. Chu EC, Huang KHK, Cheung G, Ng G, Lin A. Delayed Skin Allergy to Glucosamine Chondroitin Supplement. Cureus 2023;15(3):e36310. PubMed

113636. Rabade A, Viswanatha GL, Nandakumar K, Kishore A. Evaluation of efficacy and safety of glucosamine sulfate, chondroitin sulfate, and their combination regimen in the management of knee osteoarthritis: a systematic review and meta-analysis. Inflammopharmac PubMed

89572. Swinburne LM. Glucosamine sulphate and osteoarthritis. Lancet 2001;357(9268):1617. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Stomach pain / Vomiting Additional detail
Glucosamine
“Orally, glucosamine has been associated with gastrointestinal problems, including epigastric and abdominal pain, cramps, heartburn, diarrhea, nausea, dyspepsia, vomiting, constipation, and flatulence. In older persons, use of glucosamine sulfate is associated with oral dryness. In a clinical trial, a case of Helicobacter pylori gastritis was considered probably related to the use of glucosamine hydrochloride.”

Glucosamine · Natural Medicines adverse-effect record, reported in constipation.
6 sources cited

1520. Houpt JB, McMillan R, Wein C, Paget-Dellio SD. Effect of glucosamine hydrochloride in the treatment of pain of osteoarthritis of the knee. J Rheumatol 1999;26:2423-30.

2608. Barclay TS, Tsourounis C, McCart GM. Glucosamine. Ann Pharmacother 1998;32:574-9.

16717. Rozendaal RM, Koes BW, van Osch GJVM, et al. Effect of glucosamine sulfate on hip osteoarthritis: A randomized trial. Ann Intern Med 2008;148:268-77. PubMed

20084. Giordano N, Fioravanti A, Papakostas P, et al. The efficacy and tolerability of glucosamine sulfate in the treatment of knee osteoarthritis: a randomized, double-blind, placebo-controlled trial. Curr Ther Res Clin Exp 2009;70(3):185-196. PubMed

20104. Shaygannejad, V., Janghorbani, M., Savoj, M. R., and Ashtari, F. Effects of adjunct glucosamine sulfate on relapsing-remitting multiple sclerosis progression: preliminary findings of a randomized, placebo-controlled trial. Neurol Res 2010;32(9):981-985. PubMed

20105. Cahlin, B. J. and Dahlstrom, L. No effect of glucosamine sulfate on osteoarthritis in the temporomandibular joints--a randomized, controlled, short-term study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112(6):760-766. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Diarrhea Additional detail

Glucosamine

Recorded for Glucosamine in the same Natural Medicines adverse-effect record shown under An allergic reaction above.

Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
A skin rash Additional detail

Glucosamine

Recorded for Glucosamine in the same Natural Medicines adverse-effect record shown under Shortness of breath / A severe allergic reaction / Hives above.

Levothyroxine

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

Showing the 10 most notable of 12 shared effects — ranked by how unusual each one is, not just whether both lists mention it.

Reported for Glucosamine but not commonly for Levothyroxine: sun sensitivity, unsteadiness, liver problems and kidney problems.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Glucosamine 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.

How to take them

Some Levothyroxine Products Have a Food Rule — Glucosamine Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Glucosamine included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Levothyroxine on its own and move Glucosamine to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Levothyroxine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Overlapping uses

What Levothyroxine Is Prescribed For, and What Glucosamine Has Been Studied For

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

Levothyroxine is prescribed for: Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain. It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

Glucosamine has been studied for:

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

Glucosamine for depression

It is unclear if oral glucosamine hydrochloride reduces depression symptoms.
Cancer studied, not established Glucosamine has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

Glucosamine for cancer

Some low-quality observational studies have inconsistently found that glucosamine may be associated with a lower risk of different cancers; however, better quality evidence is needed.

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 Levothyroxine on your own; if you are taking Glucosamine for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Glucosamine or Levothyroxine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Glucosamine or Levothyroxine, 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 Levothyroxine

This page covers Glucosamine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine page lists 50 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Tiratricol (major), Acetyl-l-carnitine (moderate), Alpha-lipoic Acid (moderate) and Ascophyllum Nodosum (moderate).

By severity: 2 major · 39 moderate · 9 minor.

From our pharmacist’s overview on the Levothyroxine page

“Levothyroxine replaces a hormone your body measures in tiny amounts, so small shifts in its blood level show up in how you feel, and I treat this list with genuine care. Nearly everything on it does one of two things: blocks the pill from being absorbed in the gut, the way everyday minerals like calcium do by binding it into complexes,…”

Reviewed by 2 · Jul 18, 2026

Open the Levothyroxine interaction page

One more smart check

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

We hold 1,984 real supplement products containing Glucosamine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Glucosamine. Even though Glucosamine itself has no known interaction with Levothyroxine, 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 Glucosamine and Levothyroxine 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 Glucosamine

Top 10%

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

29 days ago today

Medication Levothyroxine

Top 10

#2 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 Glucosamine reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Glucosamine and Levothyroxine 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Glucosamine

What is Glucosamine?

Osteoarthritis
Joint pain and stiffness
Cartilage support
Knee and hip joint health

Glucosamine is a natural compound found in cartilage and joint fluid, and it is one of the most popular supplements for osteoarthritis, especially of the knee. The evidence is mixed, with some people getting modest relief while others get little to no benefit. It is generally well tolerated, but talk to your pharmacist or doctor before starting it, especially if you have a shellfish allergy or diabetes.

Derived from shellfish exoskeletons (shrimp, crab, lobster) or made synthetically; also from fungal sources · Capsules, tablets, powders, liquids; often combined with chondroitin or MSM

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

Glucosamine: dosing

There is no single official dose of glucosamine, and the right amount can depend on the form and product. If you do not notice any benefit after a reasonable trial of a couple of months, it is worth discussing whether to continue.

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

Read the full Glucosamine monograph & all interactions

Medication

About Levothyroxine

What Is Levothyroxine Used For?

Brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, Levo-T, Eltroxin, Estre, Levothyroxine, Novothyrox, Levolet

Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain.

It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

See full Levothyroxine drug information

Keep checking

Other Drugs & Glucosamine

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

2Major

13Moderate

155Minor

2,659No known interaction

2 Major 13 Moderate 155 Minor 2,659 No interaction

Major

2 interactions

Moderate

13 interactions

Minor

155 interactions

Showing 60 of 155 minor interactions — see all 155 on the Glucosamine page.

No interaction 2,659 drugs checked — show the list

We also checked Glucosamine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,659 medications checked with no known interaction — see the full Glucosamine list.

See the full Glucosamine interactions page

See every supplement checked against Levothyroxine, ranked by severity

Evidence & sources

Glucosamine References

The 58 references that drive our Glucosamine 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.

Adams ME. Hype about glucosamine. Lancet 1999;354:353-4. PubMed
Balkan B, Dunning BE. Glucosamine inhibits glucokinase in vitro and produces a glucose-specific impairment of in vivo insulin secretion in rats. Diabetes 1994;43:1173-9. PubMed
Giaccari A, Morviducci L, Zorretta D, et al. In vivo effects of glucosamine on insulin secretion and insulin sensitivity in the rat: possible relevance to the maladaptive responses to chronic hyperglycaemia. Diabetologia 1995;38:518-24. PubMed
Holmang A, Nilsson C, Niklasson M, et al. Induction of insulin resistance by glucosamine reduces blood flow but not interstitial levels of either glucose or insulin. Diabetes 1999;48:106-11. PubMed
Houpt JB, McMillan R, Wein C, Paget-Dellio SD. Effect of glucosamine hydrochloride in the treatment of pain of osteoarthritis of the knee. J Rheumatol 1999;26:2423-30.
Barclay TS, Tsourounis C, McCart GM. Glucosamine. Ann Pharmacother 1998;32:574-9.
Shankar RR, Zhu JS, Baron AD. Glucosamine infusion in rats mimics the beta-cell dysfunction of non-insulin-dependent diabetes mellitus. Metabolism 1998;47:573-7.
Almada A, Harvey P, Platt K. Effects of chronic oral glucosamine sulfate on fasting insulin resistance index (FIRI) in non-diabetic individuals. FASEB J 2000;14:A750.
Reginster JY, Deroisy R, Rovati LC, et al. Long-term effects of glucosamine sulfate on osteoarthritis progression: a randomised, placebo-controlled trial. Lancet 2001;357:251-6.
Does glucosamine increase serum lipid levels and blood pressure? Pharmacist's Letter/Prescriber's Letter 2001;17(11):171115.
Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
Monauni T, Zenti MG, Cretti A, et al. Effects of glucosamine infusion on insulin secretion and insulin action in humans. Diabetes 2000;49:926-35. PubMed
Pouwels MJ, Jacobs JR, Span PN, et al. Short-term glucosamine infusion does not affect insulin sensitivity in humans. J Clin Endocrinol Metab 2001;86:2099-103. DOI
Yun J, Tomida A, Nagata K, Tsuruo T. Glucose-regulated stresses confer resistance to VP-16 in human cancer cells through a decreased expression of DNA topoisomerase II. Oncol Res 1995;7:583-90.
Pavelka K, Gatterova J, Olejarova M, et al. Glucosamine sulfate use and delay of progression of knee osteoarthritis: A 3-year, randomized, placebo-controlled, double-blind study. Arch Intern Med 2002;162:2113-23. PubMed
Tallia AF, Cardone DA. Asthma exacerbation associated with glucosamine-chondroitin supplement. J Am Board Fam Pract 2002;15:481-4..
Scroggie DA, Albright A, Harris MD. The effect of glucosamine-chondroitin supplementation on glycosylated hemoglobin levels in patients with type 2 diabetes mellitus: a placebo-controlled, double-blinded, randomized clinical trial. Arch Intern Med 2003; PubMed
Hoffer LJ, Kaplan LN, Hamadeh MJ, et al. Sulfate could mediate the therapeutic effect of glucosamine sulfate. Metabolism 2001;50:767-70.. PubMed
Yu JG, Boies SM, Olefsky JM. The effect of oral glucosamine sulfate on insulin sensitivity in human subjects. Diabetes Care 2003;26:1941-2. PubMed
Danao-Camara T. Potential side effects of treatment with glucosamine and chondroitin. Arthritis Rheum 2000;43:2853. PubMed
Guillaume MP, Peretz A. Possible association between glucosamine treatment and renal toxicity: comment on the letter by Danao-Camara. Arthritis Rheum 2001;44:2943-4. PubMed
Rozenfeld V, Crain JL, Callahan AK. Possible augmentation of warfarin effect by glucosamine-chondroitin. Am J Health Syst Pharm 2004;61:306-307. PubMed
Tannis AJ, Barban J, Conquer JA. Effect of glucosamine supplementation on fasting and non-fasting plasma glucose and serum insulin concentrations in healthy individuals. Osteoarthritis Cartilage 2004;12:506-11. PubMed
Bush TM, Rayburn KS, Holloway SW, et al. Adverse interactions between herbal and dietary substances and prescription medications: a clinical survey. Altern Ther Health Med 2007;13:30-5.
Stumpf JL, Lin SW. Effect of glucosamine on glucose control. Ann Pharmacother 2006;40:694-8. PubMed
Pham T, Cornea A, Blick KE, et al. Oral glucosamine in doses used to treat osteoarthritis worsens insulin resistance. Am J Med Sci 2007;333:333-9. PubMed
Muniyappa R, Karne RJ, Hall G, et al. Oral glucosamine for 6 weeks at standard doses does not cause or worsen insulin resistance or endothelial dysfunction in lean or obese subjects. Diabetes 2006;55:3142-50. PubMed
Knudsen J, Sokol GH. Potential glucosamine-warfarin interaction resulting in increased international normalized ratio: Case report and review of the literature and MedWatch database. Pharmacotherapy 2008;28:540-8. PubMed
Yue QY, Strandell J, Myrberg O. Concomitant use of glucosamine potentiates the effect of warfarin. Jan 2006. Drug Safety 29(10):911-1010. DOI
Rozendaal RM, Koes BW, van Osch GJVM, et al. Effect of glucosamine sulfate on hip osteoarthritis: A randomized trial. Ann Intern Med 2008;148:268-77. PubMed
Baron AD, Zhu JS, Zhu JH, et al. Glucosamine induces insulin resistance in vivo by affecting GLUT 4 translocation in skeletal muscle. Implications for glucose toxicity. J Clin Invest 1995;96(6):2792-801. PubMed
Nelson BA, Robinson KA, Buse MG. High glucose and glucosamine induce insulin resistance via different mechanisms in 3T3-L1 adipocytes. Diabetes 2000;49(6):981-91. PubMed
Giordano N, Fioravanti A, Papakostas P, et al. The efficacy and tolerability of glucosamine sulfate in the treatment of knee osteoarthritis: a randomized, double-blind, placebo-controlled trial. Curr Ther Res Clin Exp 2009;70(3):185-196. PubMed
Shaygannejad, V., Janghorbani, M., Savoj, M. R., and Ashtari, F. Effects of adjunct glucosamine sulfate on relapsing-remitting multiple sclerosis progression: preliminary findings of a randomized, placebo-controlled trial. Neurol Res 2010;32(9):981-985. PubMed
Cahlin, B. J. and Dahlstrom, L. No effect of glucosamine sulfate on osteoarthritis in the temporomandibular joints--a randomized, controlled, short-term study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112(6):760-766. PubMed
Cerda C, Bruguera M, Parés A. Hepatotoxicity associated with glucosamine and chondroitin sulfate in patients with chronic liver disease. World J Gastroenterol 2013;19(32):5381-4. PubMed
Hochberg MC, Martel-Pelletier J, Monfort J, Möller I, Castillo JR, Arden N,Berenbaum F, Blanco FJ, Conaghan PG, Doménech G, Henrotin Y, Pap T, Richette P, Sawitzke A, du Souich P, Pelletier JP; on behalf of the MOVES Investigation Group. Combined chondroi
von Felden J, Montani M, Kessebohm K, Stickel F. Drug-induced acute liver injury mimicking autoimmune hepatitis after intake of dietary supplements containing glucosamine and chondroitin sulfate. Int J Clin Pharmacol Ther 2013;51(3):219-23. PubMed
Provenza JR, Shinjo SK, Silva JM, Peron CR, Rocha FA. Combined glucosamine and chondroitin sulfate, once or three times daily, provides clinically relevant analgesia in knee osteoarthritis. Clin Rheumatol 2015;34:1455-62. PubMed
Ossendza RA, Grandval P, Chinoune F, Rocher F, Chapel F, Bernardini D. [Acute cholestatic hepatitis due to glucosamine forte]. Gastroenterol Clin Biol. 2007 Apr;31(4):449-50.
Audimoolam VK, Bhandari S. Acute interstitial nephritis induced by glucosamine. Nephrol Dial Transplant 2006;21(7):2031. PubMed
Greenlee H, Crew KD, Shao T, Kranwinkel G, Kalinsky K, Maurer M, Brafman L, Insel B, Tsai WY, Hershman DL. Phase II study of glucosamine with chondroitin on aromatase inhibitor-associated joint symptoms in women with breast cancer. Support Care Cancer 201 PubMed
Wilkens, P., Scheel, I. B., Grundnes, O., Hellum, C., and Storheim, K. Effect of glucosamine on pain-related disability in patients with chronic low back pain and degenerative lumbar osteoarthritis: a randomized controlled trial. JAMA 2010;304(1):45-52. PubMed
Simon RR, Marks V, Leeds AR, Anderson JW. A comprehensive review of oral glucosamine use and effects on glucose metabolism in normal and diabetic individuals. Diabetes Metab Res Rev 2011;27(1):14-27. PubMed
Smidt D, Torpet LA, Nauntofte B, Heegaard KM, Pedersen AM. Associations between labial and whole salivary flow rates, systemic diseases and medications in a sample of older people. Community Dent Oral Epidemiol 2010;38(5):422-35. PubMed
Wangroongsub Y, Tanavalee A, Wilairatana V, Ngarmukos S. Comparable clinical outcomes between glucosamine sulfate-potassium chloride and glucosamine sulfate sodium chloride in patients with mild and moderate knee osteoarthritis: a randomized, double-blind
Chopra A, Saluja M, Tillu G, Venugopalan A, Sarmukaddam S, Raut AK, Bichile L, Narsimulu G, Handa R, Patwardhan B. A Randomized Controlled Exploratory Evaluation of Standardized Ayurvedic Formulations in Symptomatic Osteoarthritis Knees: A Government of I
Swinburne LM. Glucosamine sulphate and osteoarthritis. Lancet 2001;357(9268):1617. PubMed
Murphy RK, Ketzler L, Rice RD, Johnson SM, Doss MS, Jaccoma EH. Oral glucosamine supplements as a possible ocular hypertensive agent. JAMA Ophthalmol 2013;131(7):955-7. PubMed
Kimball AB, Kaczvinsky JR, Li J, et al. Reduction in the appearance of facial hyperpigmentation after use of moisturizers with a combination of topical niacinamide and N-acetyl glucosamine: results of a randomized, double-blind, vehicle-controlled trial.
Ma H, Li X, Sun D, et al. Association of habitual glucosamine use with risk of cardiovascular disease: prospective study in UK Biobank. BMJ. 2019 May 14;365:l1628. PubMed
Hoban C, Byard R, Musgrave I. Hypersensitive adverse drug reactions to glucosamine and chondroitin preparations in Australia between 2000 and 2011. Postgrad Med J. 2019 Oct 9. pii: postgradmedj-2019-136957. PubMed
Tenti S, Veronese N, Cheleschi S, et al. Prescription-grade crystalline glucosamine sulfate as an add-on therapy to conventional treatments in erosive osteoarthritis of the hand: results from a 6-month observational retrospective study. Aging Clin Exp Res PubMed
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Lila AM, Alekseeva LI, Baranov AA, et al. Chondroitin sulfate and glucosamine combination in patients with knee and hip osteoarthritis: A long-term observational study in Russia. World J Orthop 2023;14(6):443-457. PubMed
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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 Glucosamine and Levothyroxine Together: Common Questions

Is it safe to take Glucosamine with Levothyroxine?

We do not list a known interaction between Glucosamine and Levothyroxine. 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 Glucosamine and Levothyroxine have any of the same side effects?

Yes — our sources link each of them separately to 10 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.

Should I take Glucosamine and Levothyroxine at the same time of day?

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Levothyroxine on its own and move Glucosamine to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.

Are Glucosamine and Levothyroxine 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 Glucosamine in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.

How was the Glucosamine and Levothyroxine combination checked?

Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Glucosamine has documented interactions with 4 drug classes — none of Levothyroxine'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 Glucosamine interact with any other medications?

Yes. Glucosamine has 170 documented drug interactions in our database — Levothyroxine 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 Levothyroxine interact with any supplements?

Yes. Levothyroxine has documented interactions with 50 supplements in our database — Glucosamine is not one of them. The Levothyroxine interaction page linked on this page lists every one, ranked by severity.

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

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Keep Exploring

Glucosamine monograph Uses, safety profile, and every drug interaction in one place Levothyroxine drug information The full plain-English guide to this medication Levothyroxine supplement interactions Every supplement checked against Levothyroxine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 58 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

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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.