Glucosamine

Aminomonosaccharide; supplement / OTC product positioned as a chondroprotective agent

ATC code: M01AX05 (Glucosamine)

Brand names

Move Free, Cosamin, Schiff

Mechanism of action

Endogenous substrate for the synthesis of glycosaminoglycans and proteoglycans of articular cartilage. Theoretically: oral intake raises substrate availability for chondrocytes and may stimulate cartilage matrix synthesis. In practice oral bioavailability is around 20%, and synovial fluid concentrations are 100–500 times below those used in vitro to demonstrate chondrocyte stimulation. A weak anti-inflammatory effect through NF-κB suppression is also described. Real clinical efficacy depends on the salt form (sulphate or hydrochloride) and is markedly lower than marketing claims.

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Knee osteoarthritis

Not recommended

Glucosamine is heavily marketed as a «chondroprotective agent» for knee osteoarthritis, promising «cartilage restoration» and «stopping arthritis progression». Evidence is weak. The GAIT 2006 trial (NEJM) in 1583 patients with knee OA showed no superiority over placebo on the WOMAC scale. Cochrane 2005 found a small pain reduction only for glucosamine sulphate in industry-sponsored trials; independent studies show no difference. SER 2023 does not include glucosamine in core osteoarthritis recommendations – first line is paracetamol, topical NSAIDs, physical activity and weight loss; with insufficient response, short courses of systemic NSAIDs. AEMPS classifies glucosamine products as OTC with a note on limited evidence. In Spain it is registered both as medication (Xicil, Dolenio) and as a food supplement. If glucosamine is offered as the main osteoarthritis treatment, consider seeking a second opinion: time spent on ineffective therapy delays uptake of strategies that work (exercise, weight control).

Sources

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Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMA

Spanish Medicines Information Centre (CIMA)

Label dated: 03/26/2026

FDA / DailyMed

FDA — DailyMed Drug Labels

Label dated: 02/02/2024

Safety

Contraindications

Hypersensitivity to glucosamine or to shellfish (source material)
Phenylketonuria (formulations with aspartame)
Age under 18 years
Pregnancy and lactation (AEMPS – lack of data)

Serious adverse effects

Severe allergic reactions in shellfish-sensitive patients
Enhanced warfarin effect with INR rise (bleeding cases reported)
Glycaemia increase in patients with type 2 diabetes (small effect, clinical relevance debated)

Common adverse effects

Dyspepsia and nausea
Heartburn
Diarrhoea or constipation
Headache
Drowsiness
Skin rash

PregnancyFDA N

Not classified. No human pregnancy data. In Spain glucosamine is regarded as a food supplement under RD 1487/2009, without AEMPS-recognised therapeutic indications. AEMPS and AESAN advise against use during pregnancy due to lack of data. SEGO does not include glucosamine in pregnancy pain recommendations.

Breastfeeding

No data. eLactancia: «possible risk, safety not confirmed». For osteoarthritis treatment in a breastfeeding mother, paracetamol (L1) and topical NSAIDs (L2) are preferred.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Glucosamine used for?

Glucosamine is evaluated for the following indications with varying evidence strength: Knee osteoarthritis (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Glucosamine?

Common side effects of Glucosamine (≥ 1 in 100): Dyspepsia and nausea, Heartburn, Diarrhoea or constipation, Headache, Drowsiness, Skin rash. See the Safety section for uncommon and serious reactions.

Is Glucosamine safe during pregnancy?

FDA category N. Not classified. No human pregnancy data. In Spain glucosamine is regarded as a food supplement under RD 1487/2009, without AEMPS-recognised therapeutic indications. AEMPS and AESAN advise against use during pregnancy due to lack of data. SEGO does not include glucosamine in pregnancy pain recommendations.

Is Glucosamine compatible with breastfeeding?

No data. eLactancia: «possible risk, safety not confirmed». For osteoarthritis treatment in a breastfeeding mother, paracetamol (L1) and topical NSAIDs (L2) are preferred.

Who should not take Glucosamine?

Glucosamine is contraindicated in: Hypersensitivity to glucosamine or to shellfish (source material); Phenylketonuria (formulations with aspartame); Age under 18 years; Pregnancy and lactation (AEMPS – lack of data). Full list in the Safety section.

Mechanism of action

Safety

Contraindications

Hypersensitivity to glucosamine or to shellfish (source material)
Phenylketonuria (formulations with aspartame)
Age under 18 years
Pregnancy and lactation (AEMPS – lack of data)

Serious adverse effects

Severe allergic reactions in shellfish-sensitive patients
Enhanced warfarin effect with INR rise (bleeding cases reported)
Glycaemia increase in patients with type 2 diabetes (small effect, clinical relevance debated)

Common adverse effects

Dyspepsia and nausea
Heartburn
Diarrhoea or constipation
Headache
Drowsiness
Skin rash

PregnancyFDA N

Breastfeeding

No data. eLactancia: «possible risk, safety not confirmed». For osteoarthritis treatment in a breastfeeding mother, paracetamol (L1) and topical NSAIDs (L2) are preferred.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Frequently asked

What is Glucosamine used for?

What are the side effects of Glucosamine?

Is Glucosamine safe during pregnancy?

Is Glucosamine compatible with breastfeeding?

No data. eLactancia: «possible risk, safety not confirmed». For osteoarthritis treatment in a breastfeeding mother, paracetamol (L1) and topical NSAIDs (L2) are preferred.

Who should not take Glucosamine?