Glucosamine (C₆H₁₄NO₅) is a dietary supplement distributed as a salt -- commonly, but not limited to, glucosamine HCl, glucosamine sulfate potassium, and glucosamine sulfate sodium. Common dosages of glucosamine are 1,500 mg per day. The salt (e.g. glucosamine sulfate * KCL, glucosamine sulfate * NACL) forms are necessary to stabilize the glucosamine sulfate, whereas glucosamine HCl is stable without requiring a salt to be bound to it.

Glucosamine sulfate is a synthetic version of a compound the human body makes to stimulate the growth of cartilage. The theory is that these compounds rebuild cartilage and reduce the symptoms of arthritis.

The chemical is an acceptable treatment in veterinary medicine, but the Arthritis Foundation and the American College of Rheumatology have not recommended it for humans. The Food and Drug Administration has not approved it to treat arthritis. At this time, they are sold as nutritional supplements, and therefore do not need evidence that they are safe and effective.

Current research shows it may play a role in relieving pain associated with osteoarthritis. As used, it is often paired with MSM. The National Institute of Health is, as of 2004, conducting a study to see the effects of chondroitin and glucosamine on osteoporosis and osteoarthritis.