Oral glucosamine is a dietary supplement and is not a pharmaceutical drug. Glucosamine is marketed to support the structure and function of joints and the marketing is targeted to people suffering from osteoarthritis. Commonly sold forms of glucosamine are glucosamine sulfate, glucosamine hydrochloride, and N-acetylglucosamine. Glucosamine is often sold in combination with other supplements such as chondroitin sulfate and methylsulfonylmethane. Of the three commonly available forms of glucosamine, only glucosamine sulfate is given a “likely effective” rating for treating osteoarthritis.
Evaluation for health effects
Since glucosamine is a precursor for glycosaminoglycans, and glycosaminoglycans are a major component of joint cartilage, supplemental glucosamine may or may not influence cartilage structure, and so may or may not apply to alleviation of arthritis. Its use as a therapy for osteoarthritis appears safe, but there is not yet unequivocal evidence for its effectiveness. There have been multiple clinical trials testing glucosamine as a potential medical therapy for osteoarthritis, but results have been inconclusive at best.