Supplements

Glucosamine & Chondroitin

Updated · 26 sources · Editorial policy

Glucosamine and chondroitin sulfate are two building blocks of joint cartilage that are sold, alone or together, as supplements for osteoarthritis (OA), mostly knee OA. In the US both are dietary supplements. In some other countries, certain preparations are prescription drugs (NCCIH).

The most important fact is that the evidence is contested. The largest publicly funded trial, the NIH-sponsored GAIT study, found no overall benefit over placebo. Results differ by product and by who funded the trial. Major guidelines also disagree. The ACR and OARSI recommend against both supplements for knee OA, and the UK’s NICE advises against glucosamine. The European ESCEO algorithm recommends specific prescription-grade products.

This page summarizes what the clinical trials, meta-analyses and guidelines report. It is for education only and is not medical advice.

Property Detail
Class Glucosamine: amino sugar. Chondroitin sulfate: glycosaminoglycan (a long sugar chain found in cartilage)
Common forms Glucosamine sulfate (including a patented crystalline form), glucosamine hydrochloride, chondroitin sulfate
Route Oral
Doses used in major trials Glucosamine 1,500 mg/day; chondroitin sulfate 800–1,200 mg/day
Half-life Glucosamine ≈ 15 h, a tentative estimate from one pharmacokinetic study (Persiani 2005); no comparable figure for chondroitin
Main studied use Pain and function in knee osteoarthritis; possible slowing of joint space narrowing
US status Dietary supplement, not an FDA-approved drug
Guideline positions ACR 2019, OARSI 2019: recommend against for knee OA. NICE 2022: do not offer glucosamine. ESCEO 2019: recommends prescription crystalline glucosamine sulfate and pharmaceutical-grade chondroitin sulfate

What it is

Both substances occur naturally in joint cartilage (NCCIH):

  • Glucosamine is an amino sugar. The body uses it to build glycosaminoglycans, the long sugar chains that form part of cartilage’s structure.
  • Chondroitin sulfate is one of those glycosaminoglycans. It helps cartilage resist compression.

The idea behind supplementation is that supplying these building blocks might support cartilage or slow its breakdown. Whether that happens in people is exactly what the trials below tested.

The products on the market are not interchangeable, and the research treats them as different:

Form What it is Notes
Crystalline glucosamine sulfate A patented formulation (Persiani 2005), studied at 1,500 mg once daily; the Rottapharm/Madaus product in meta-analyses The brand behind most positive trials (Eriksen 2014); sold on prescription in some countries
Other glucosamine sulfate Supplement-grade sulfate salts Variable quality
Glucosamine hydrochloride A different salt Used in GAIT and in the MOVES combination
Pharmaceutical-grade chondroitin sulfate Purified, characterized product, often 800 mg/day Used in the positive European trials
Supplement-grade chondroitin sulfate Animal-derived, sometimes of mixed animal origin Content and purity vary widely (see Quality)

Pharmacokinetics

Glucosamine is absorbed well enough to raise blood levels. In 12 healthy volunteers given crystalline glucosamine sulfate once daily (Persiani et al., Osteoarthritis Cartilage 2005):

Finding Result
Baseline (natural) plasma glucosamine 10.4–204 ng/mL
Peak at 1,500 mg once daily About 10 µM, over 30 times baseline
Dose proportionality Linear from 750 to 1,500 mg; less than proportional at 3,000 mg
Elimination half-life Tentatively estimated at about 15 h

The authors concluded that the kinetics support once-daily dosing. The study was run by the manufacturer, and the half-life was labeled as a tentative estimate. The 15-hour value in our compound database matches this figure.

Chondroitin is a much larger molecule, and fewer kinetic data exist. In 20 healthy men given a single 4 g dose of a bovine chondroitin sulfate drug, plasma chondroitin rose more than 200%, peaked at about 2 hours and stayed significantly raised from 2 to 6 hours. Changes in the plasma sugar profile indicated that part of the dose was absorbed, partly broken down (Volpi, Osteoarthritis Cartilage 2002).

Regulatory status

  • United States. Glucosamine (as sulfate or hydrochloride) and chondroitin sulfate are sold as dietary supplements, separately or together (NCCIH). They are not FDA-approved drugs.
  • Other countries. Certain preparations are sold as prescription drugs (NCCIH). In Europe, the patented crystalline glucosamine sulfate and pharmaceutical-grade chondroitin sulfate are the forms the ESCEO guideline refers to.

What the research shows

GAIT: the largest independent trial

The Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), funded by the US National Institutes of Health, randomized 1,583 people with painful knee OA to one of five arms for 24 weeks (Clegg et al., NEJM 2006). The glucosamine was the hydrochloride salt (NCCIH). The primary outcome was a 20% or greater drop in knee pain.

Arm (daily dose) Response rate vs placebo p value
Placebo 60.1% responded —
Glucosamine 1,500 mg +3.9 percentage points 0.30
Chondroitin sulfate 1,200 mg +5.3 percentage points 0.17
Both combined +6.5 percentage points 0.09
Celecoxib 200 mg (active control) +10.0 percentage points 0.008

Key points:

  • No supplement arm beat placebo in the whole group. Celecoxib, a prescription anti-inflammatory, did.
  • The placebo response was large: 60% of placebo patients met the response threshold.
  • Subgroup signal. In the 354 people with moderate-to-severe pain, the combination had a higher response rate than placebo (79.2% vs 54.3%, p = 0.002). The authors labeled this analysis exploratory.

Two 2-year ancillary GAIT studies followed part of the group:

  • Pain (n = 662). No treatment reached a clinically important difference from placebo in WOMAC pain or function. The odds of a 20% pain reduction versus placebo were 1.16 for glucosamine, 0.83 for the combination and 0.69 for chondroitin, none significant (Sawitzke et al., Ann Rheum Dis 2010).
  • Joint structure (n = 572). Knees on placebo lost a mean 0.166 mm of joint space width over 2 years. No treatment group differed significantly from placebo. The authors noted the study had limited power because joint space loss was smaller than expected (Sawitzke et al., Arthritis Rheum 2008).

Glucosamine sulfate trials on joint structure

Two 3-year, placebo-controlled trials of glucosamine sulfate 1,500 mg once daily reported slower joint space narrowing on X-ray:

Trial n Joint space change, placebo Joint space change, glucosamine sulfate
Reginster et al., Lancet 2001 212 −0.31 mm (95% CI −0.48 to −0.13) −0.06 mm (95% CI −0.22 to 0.09)
Pavelká et al., Arch Intern Med 2002 202 −0.19 mm (95% CI −0.29 to −0.09) +0.04 mm (95% CI −0.06 to 0.14); p = 0.001 vs placebo

In the Pavelká trial, fewer glucosamine patients had severe narrowing of more than 0.5 mm (5% vs 14%, p = 0.05), and symptom scores also improved. Neither result was reproduced in the independent GAIT structure study, which used glucosamine hydrochloride.

Combination trials after GAIT

Trial Design Result
LEGS (Fransen et al., Ann Rheum Dis 2015) 605 people, 2 years; glucosamine sulfate 1,500 mg, chondroitin 800 mg, both, or placebo Combination slightly reduced joint space narrowing (mean difference 0.10 mm, 95% CI 0.002–0.20, p = 0.046). No arm improved pain more than placebo
MOVES (Hochberg et al., Ann Rheum Dis 2016) 606 people with moderate-to-severe pain, 6 months; chondroitin 400 mg plus glucosamine hydrochloride 500 mg three times daily vs celecoxib 200 mg Combination non-inferior to celecoxib: WOMAC pain fell ≈ 50% in both arms. No placebo arm
Roman-Blas et al., Arthritis Rheumatol 2017 164 people with moderate-to-severe pain, 6 months; chondroitin 1,200 mg plus glucosamine sulfate 1,500 mg vs placebo Combination did worse than placebo on pain in the main analysis (19% vs 33% reduction); no difference in per-protocol completers

MOVES had no placebo arm. It therefore cannot separate a drug effect from the large placebo response seen in GAIT and in the Roman-Blas trial.

Chondroitin trials

  • Knee OA (CONCEPT). In 604 patients, pharmaceutical-grade chondroitin sulfate 800 mg/day reduced pain at 6 months by 42.6 mm on a 100 mm scale, vs 39.5 mm for celecoxib and 33.3 mm for placebo (p = 0.001 for chondroitin vs placebo) (Reginster et al., Ann Rheum Dis 2017).
  • Hand OA. In a single-center trial of 162 patients, chondroitin 800 mg/day improved hand pain by 8.7 mm more than placebo (p = 0.016) and also improved hand function (Gabay et al., Arthritis Rheum 2011). This trial is the basis of the ACR’s conditional recommendation for chondroitin in hand OA.

Meta-analyses

Review Scope Main finding
Cochrane, glucosamine (Towheed et al., 2005) 20 RCTs, 2,570 patients Overall pain benefit (SMD −0.61, 95% CI −0.95 to −0.28), but not in the 8 trials with adequate allocation concealment. Rotta-product trials positive (SMD −1.31); non-Rotta trials not (SMD −0.15, 95% CI −0.35 to 0.05)
Network meta-analysis (Wandel et al., BMJ 2010) 10 large trials, 3,803 patients Pain vs placebo on a 10 cm scale: glucosamine −0.4 cm, chondroitin −0.3 cm, combination −0.5 cm. No credible interval reached the prespecified 0.9 cm minimal clinically important difference. Industry-independent trials showed smaller effects (p = 0.02)
Glucosamine by brand (Eriksen et al., Arthritis Care Res 2014) 25 trials, 3,458 patients Brand explained the most heterogeneity. Rottapharm/Madaus trials: SMD −1.07; only its 3 low-risk-of-bias trials: SMD −0.27 (small). Other products: SMD −0.11 (95% CI −0.46 to 0.24)
Individual patient data (Runhaar et al., Ann Rheum Dis 2017) 5 industry-independent trials, 1,625 patients Glucosamine no better than placebo at 3 or 24 months, and no better in any subgroup (pain severity, BMI, sex, structure, inflammation)
Cochrane, chondroitin (Singh et al., 2015) 43 RCTs; 4,962 on chondroitin, 4,148 controls Pain about 8 points better on a 0–100 scale in short trials (mostly low quality, high heterogeneity). In 2 high-quality trials, 20% pain reduction in 53 vs 47 per 100. Benefit uncertain when limited to large, well-concealed or non-industry trials

Across these reviews, the pattern is consistent. Small benefits appear mainly in older, smaller or manufacturer-sponsored trials. Effects shrink or vanish in larger, independent, low-risk-of-bias trials.

Guidelines disagree

Guideline Glucosamine Chondroitin
ACR/Arthritis Foundation 2019 (Kolasinski et al.) Strongly recommended against for knee, hip and hand OA Strongly recommended against for knee and hip OA, including combination products; conditionally recommended for hand OA
OARSI 2019 (Bannuru et al.) Strongly recommended against for knee OA Strongly recommended against for knee OA
NICE NG226, UK 2022 (NICE) “Do not offer glucosamine” Not addressed
AAOS 2021 (orthopaedic surgeons, per NCCIH) Listed among supplements that may help mild-to-moderate knee OA; evidence called inconsistent Same
ESCEO 2019 (Bruyère et al.) Strongly recommends prescription crystalline glucosamine sulfate; discourages other glucosamine forms Strongly recommends pharmaceutical-grade (prescription) chondroitin sulfate, distinct from other products

The ACR explained its change from a conditional to a strong recommendation against glucosamine. It cited different results in industry-sponsored and publicly funded trials, concerns about publication bias, and the failure of the lowest-risk-of-bias data to show important benefit (ACR guideline full text). OARSI and NICE cite lack of efficacy.

ESCEO’s position rests on the argument that the products are not interchangeable. In its view, the positive data for the crystalline glucosamine sulfate and pharmaceutical-grade chondroitin should not be diluted by trials of other products. A joint review by authors from both groups summarized the split. ESCEO recommends pharmaceutical-grade glucosamine and chondroitin, while OARSI “strongly recommends against their use (including all glucosamine and chondroitin formulations)” (Arden et al., Nat Rev Rheumatol 2021). Two ESCEO authors, Reginster and Bruyère, were also authors of the 2001 Lancet glucosamine sulfate trial.

Side effects and risks

General tolerability

In the large trials, side effects were mild and similar to placebo:

  • GAIT. Adverse events were “mild, infrequent, and evenly distributed” across arms (Clegg et al., NEJM 2006).
  • Cochrane, glucosamine. Adverse reactions were no more common than with placebo (RR 0.97, 95% CI 0.88–1.08) (Towheed et al., 2005).
  • Cochrane, chondroitin. Serious adverse events were less common than with control (Peto OR 0.40, 95% CI 0.19–0.82) (Singh et al., 2015).

NCCIH notes that little is known about safety during pregnancy or breastfeeding (NCCIH).

Warfarin interaction

This is the best-documented risk. FDA authors described a 71-year-old man on stable warfarin whose INR (a measure of how slowly blood clots) rose from 2.3 to 3.9 about 3 weeks after he raised his glucosamine-chondroitin dose. It reached 4.7 after a dose reduction and fell to 2.6 once the supplement was stopped and warfarin was adjusted (Knudsen and Sokol, Pharmacotherapy 2008). The same review found:

  • 20 FDA MedWatch reports of altered clotting with glucosamine or glucosamine-chondroitin in warfarin users, including one brain bleed that left the patient in a persistent vegetative state;
  • 21 WHO reports of raised INR with glucosamine, 17 of which resolved when glucosamine was stopped.

These are case reports, so they cannot give a rate, but NCCIH also lists the bleeding risk with warfarin.

Blood sugar

Whether glucosamine affects blood sugar has been debated. A review of long-term trials, including people with type 2 diabetes and prediabetes, found no significant rise in fasting glucose for up to 3 years. It noted that no definitive long-term studies exist in prediabetes (Simon et al., Diabetes Metab Res Rev 2011). The ACR guideline notes that “some patients exposed to glucosamine may show elevations in serum glucose levels.” NCCIH says glucosamine may raise blood sugar in some people.

Quality and contamination

Supplements do not undergo the quality controls required of pharmaceuticals, so the label may not match the contents. One study analyzed 25 glucosamine and chondroitin supplements from 8 European countries against 2 pharmaceutical products (Restaino et al., Carbohydr Polym 2019):

  • more than 19 of the 25 contained less chondroitin or glucosamine than declared, by up to 60.3%;
  • all contained keratan sulfate, a related but different sugar chain, at up to 47.1%;
  • more than 32% contained chondroitin of mixed animal origin or multiple molecular-weight species.

This variability is part of why ESCEO separates pharmaceutical-grade products from supplements. It also makes it hard to apply any single trial result to a store-bought product.

Key takeaways

  • The largest independent trial was negative. In GAIT (1,583 patients), glucosamine, chondroitin and the combination were not significantly better than placebo for knee pain at 24 weeks. Celecoxib was.
  • Effects shrink as trial quality rises. Meta-analyses find small or no benefit in large, industry-independent, low-risk-of-bias trials. Larger effects come mainly from manufacturer-linked trials of one glucosamine sulfate brand.
  • Product matters, or seems to. Crystalline glucosamine sulfate and pharmaceutical-grade chondroitin have the most favorable data. Other glucosamine products have consistently failed to beat placebo for pain in pooled analyses.
  • Guidelines split. ACR and OARSI advise against both for knee OA, and NICE against glucosamine. ESCEO recommends the prescription-grade forms, and the ACR conditionally supports chondroitin for hand OA.
  • Low toxicity, one key interaction. Side effects in trials were similar to placebo, but case reports link glucosamine with raised INR and bleeding in people taking warfarin.
  • Labels may be inaccurate. In one European analysis, most supplements contained less active ingredient than declared, and all were contaminated with keratan sulfate.

Sources

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