Conclusive evidence is lacking to support the effectiveness of glucosamine against arthritis.
Cartilage is composed of collagen, elastin, and sugar-protein molecules, that make it gel-like, resilient, and act as a shock absorber. Osteoarthritis is characterized by progressive cartilage degeneration. Glucosamine may help with formation of the sugar-protein molecules, which would slow the degeneration of cartilage. However, clinical trials yielded mixed results. Glucosamine may reduce inflammation and protect cartilage from damage caused by NSAIDs and corticosteroids.
To reduce inflammation
Glucosamine may reduce inflammation in a way that is different from non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen.
To prevent osteoarthritis and treat disease progression
Several clinical trials of glucosamine alone and in combination with chondroitin sulfate yielded mixed results.
To treat temporomandibular joint disorder (TMJ)
Two clinical trials support the use of glucosamine in combination with chondroitin sulfate to treat TMJ.
Patients with liver disease should avoid taking glucosamine, as there are case reports of liver injury/toxicity.
Patients who are taking blood-thinners or who have glaucoma or diabetes should tell their healthcare professionals if they are taking glucosamine. There is some preliminary evidence for potential side effects and related monitoring needs should be discussed.
Do Not Take If
You are allergic to shellfish: Some glucosamine products are derived from chitin, the exoskeleton on shellfish. Ask your doctor if you might have an adverse reaction to glucosamine.
You have liver disease: There are several case reports of liver injury/toxicity in patients with liver disease.
Glucosamine tends to be safe and well tolerated, but caution should be exercised in certain populations (see Warnings and Interactions). Rare reactions include gastrointestinal complaints and allergic reactions.
Increased warfarin effects or INR levels (related to blood-thinning medication monitoring): Occurred with glucosamine-chondroitin; lab tests returned to normal levels when glucosamine was discontinued.
Liver injury/toxicity and elevated lab values: In patients with liver disease.
Increased fluid pressure inside the eye: In older patients with osteoarthritis who took glucosamine supplements in a study. The meaning of this finding needs further evaluation.
Reduced glucose tolerance: From infusion and oral forms of glucosamine.
Glucosamine has not been found effective in relieving back pain.
Glucosamine may have a limited effect, more likely in older patients who have arthritis that is more severe or for longer periods of time.
Glucosamine may take longer to act than NSAIDs, but once it does, its effects last longer after treatment is stopped.
Glucosamine is an endogenous aminomonosaccharide synthesized from glucose. Found in mucopolysaccharides, mucoproteins and chitin, a cellulose-like biopolymer in marine invertebrate exoskeletons, it is used in the biosynthesis of proteoglycans and glycosaminoglycans, sugar-protein molecules found in cartilage. Glucosamine also has anti-inflammatory activity. Both oral and injectable forms have been studied for osteoarthritis. Glucosamine is marketed as a dietary supplement and often paired with chondroitin sulfate for joint health.
In earlier studies, glucosamine and chondroitin reduced degenerative and temporomandibular joint (TMJ) disease symptoms (1). Although glucosamine/chondroitin supplementation was comparable to celecoxib in a large multicenter trial of patients with severe knee osteoarthritis (OA) pain (2), other studies have not found benefit with glucosamine, chondroitin, or the combination for knee or hip OA (3)(4)(5)(6)(7)(8)(9)(10). Data on chondroitin alone also suggest no significant benefit (10)(11). In addition, no efficacy was seen with glucosamine in relieving back pain (12)(13), degenerative lumbar OA (13), or improving glucose metabolism in type 2 diabetes (14). Any benefits with glucosamine may be limited to older patients who have arthritis that is more severe (15) or for longer periods of time (16).
Epidemiological studies suggest potential reduction for some cancer risks and mortality with long-term glucosamine/chondroitin supplementation, although limitations such as bias could not be ruled out and confirmatory studies are needed (17)(18)(19).
There are case reports of liver injury/toxicity related to glucosamine consumption (20)(21). Patients on antiplatelet or anticoagulant therapies should be monitored for interactions or increased INR levels (22)(23). Patients with poorly controlled diabetes or glucose intolerance should be monitored as glucosamine could worsen insulin resistance (24)(25).
Temporomandibular joint disorder (TMJ)
Mechanism of Action
Progressive degeneration of cartilage glycosaminoglycans is evident in osteoarthritis. Glucosamine is the first step in glycosaminoglycan biosynthesis. In vitro, it increased production of monomeric proteoglycans capable of assembling into high molecular weight aggregates (26). Glucosamine can protect cartilage from metabolic impairment by NSAIDs, corticosteroids, and by exerting anti-inflammatory effects (27). Glucosamine can promote cartilage repair by inducing tissue TGFβ1 and CTGF expression that regulates chondrocyte proliferation (28).
The rise in intraocular pressure associated with older patients in one study may relate to exogenous glycosaminoglycans (GAG) effects on accumulations of extracellular matrix and thickening of the basement membrane, thereby compromising function of the trabecular meshwork (29). Reduced systemic inflammation and cytokine activity found in a small randomized crossover study may explain potential reductions in mortality or cancer risk (30).
Glucosamine is slow to act (31) but the effects persist after cessation of treatment (26).
Patients with liver disease should avoid taking glucosamine, as it is extensively metabolized in the liver and there are case reports of liver injury/toxicity (20)(21).
Patients who are taking anticoagulants or antiplatelet drugs or who have glaucoma or diabetes should be monitored, as there is some preliminary evidence for potential side effects (22)(23)(24)(25)(29).
Individuals should consult their doctor if allergic to shellfish (32).
Glucosamine tends to be safe and well tolerated, but caution should be exercised in certain populations (see Warnings and Interactions). Rare reactions include gastrointestinal complaints (33) and allergic reactions (20).
Case Reports Increased intraocular pressure: In a randomized double-blind trial, glucosamine sulfate supplementation significantly increased intraocular pressure in older patients with OA (29). The implication of this finding needs further evaluation. Liver injury/hepatotoxicity and elevated aminotransferase values: In patients with liver disease (20)(21). Reduced glucose tolerance: From infusion and oral forms of glucosamine (34).
Warfarin: Although more information is needed to define this interaction, glucosamine-chondroitin may potentiate warfarin effects and increase INR levels (22).
Anticoagulants/Antiplatelets: Use of glucosamine may inhibit platelet aggregation (23).
Herb Lab Interactions
Blood glucose levels: May be affected by glucosamine (34).
Increased International Normalized Ratio (INR): Glucosamine was associated with increased INR that return to normal levels when discontinued (22).
Elevated aminotransferase values: In patients with liver disease (20).