Glucosamine (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of two polysaccharides, chitosan and chitin. Glucosamine is one of the most abundant monosaccharides. It is produced commercially by the hydrolysis of shellfish exoskeletons or, less commonly, by fermentation of a grain such as corn or wheat. Glucosamine has various names depending on the country and its intended use. Although a common dietary supplement, there is little clinical evidence that it is effective for relief of arthritis or pain, and is not an approved prescription drug in most countries, although it is listed as a medicinal product in Europe. Worldwide, there are no clinical organizations that recommend use of glucosamine as a treatment for arthritis.
Absence of clinical recommendations No national clinical organizations recommend use of glucosamine for relief from arthritis. These include medical associations in Australia, Canada, the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis, the United Kingdom National Institute for Health and Care Excellence, the United States National Center for Complementary and Integrative Health, and the American College of Rheumatology and American Arthritis Foundation.
Recommendations against use Several clinical organizations have explicitly recommended against use of glucosamine to treat arthritis, stating that it has not been proven to be effective, that it may have negative interactions with prescription drugs, and that it may cause allergic reactions in people sensitive to shellfish, a common starting material in glucosamine manufacturing. The American College of Rheumatology and American Arthritis Foundation stated that "glucosamine is strongly recommended against in patients with knee, hip, and/or hand osteoarthritis".
Dietary supplement Oral glucosamine is a dietary supplement and is not a prescription drug in the United States. Glucosamine is marketed as a supplement to support the structure and function of joints, and the marketing is targeted to people with osteoarthritis. Commonly sold forms of glucosamine are glucosamine sulfate, glucosamine hydrochloride, and N-acetylglucosamine. Of the three commonly available forms of glucosamine, only glucosamine sulfate is given a "likely effective" rating for treating osteoarthritis. Glucosamine is often sold in combination with other supplements such as chondroitin sulfate and methylsulfonylmethane. Glucosamine, along with commonly used chondroitin, is not routinely prescribed to treat people who have symptomatic osteoarthritis of the knee, as there is insufficient evidence that this treatment is helpful. As is common with heavily promoted dietary supplements, the claimed benefits of glucosamine are based principally on individual clinical and laboratory studies. Clinical studies on glucosamine efficacy are divided, with some reporting relief from arthritic pain and stiffness, while most studies report no conclusive benefit above placebo.
Adverse effects and drug interactions Glucosamine with or without chondroitin elevates the international normalized ratio (INR) in individuals who are taking the anticoagulant warfarin. Adverse effects are mild and infrequent, including stomach upset, constipation, diarrhea, headache, and rash. Since glucosamine is usually derived from the shells of shellfish, it may be unsafe for those with shellfish allergy. Many manufacturers of glucosamine derived from shellfish include a warning that those with a seafood allergy should consult a healthcare professional before taking the product.
Biochemistry Glucosamine is naturally present in the shells (exoskeletons) of shellfish, animal bones, bone marrow, and fungi. D-Glucosamine is made naturally in the form of glucosamine-6-phosphate, and is the biochemical precursor of all nitrogen-containing sugars. Specifically in humans, glucosamine-6-phosphate is synthesized from fructose 6-phosphate and glutamine by glutamine—fructose-6-phosphate transaminase as the first step of the hexosamine biosynthesis pathway. The end-product of this pathway is uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), which is then used for making glycosaminoglycans, proteoglycans, and glycolipids. As the formation of glucosamine-6-phosphate is the first step for the synthesis of these products, glucosamine may be important in regulating their production; however, the way that the hexosamine biosynthesis pathway is actually regulated, and whether this could be involved in contributing to human disease remains unclear.
Manufacturing Most glucosamine is manufactured by processing chitin from the exoskeletons of shellfish, including shrimp, lobsters, and crabs.
History Glucosamine was first prepared in 1876 by Georg Ledderhose by the hydrolysis of chitin with concentrated hydrochloric acid. The stereochemistry was not fully determined until the 1939 work of Walter Haworth.
Legal status
United States In the United States, glucosamine is not approved by the Food and Drug Administration (FDA) for medical use in humans. Because glucosamine is classified as a dietary supplement in the United States, the FDA requires evidence of its safety, but not its effectiveness, as long as it is not marketed as a treatment for any medical condition. In 2004, the FDA declared there was insufficient evidence for supplement manufacturers to state that glucosamine was effective for treating arthritis, joint degeneration, or cartilage deterioration, a position remaining in effect, as of 2025.
Europe In most of Europe, glucosamine is approved as a medical drug and is sold in the form of glucosamine sulfate. The Task Force of the European League Against Rheumatism (EULAR) committee has granted glucosamine sulfate a level of toxicity of 5 on a 0–100 scale. By 2014, OARSI no longer recommended glucosamine for disease modification and deemed its effectiveness for symptom relief in knee osteoarthritis as "uncertain." A 2016 review concluded that only the formulated prescription-only patented crystalline glucosamine sulfate had efficacy in the treatment of arthritis.
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