Glucosamineis a natural compound found in cartilage the tough tissue that cushionsjoints. In supplement form, glucosamine is harvested from shells of shellfishor made in a lab. There are several forms of glucosamine, including glucosaminesulfate, glucosamine hydrochloride and N-acetyl glucosamine. These supplementsaren't considered interchangeable.People use glucosamine sulfate orally totreat a painful condition caused by the inflammation, breakdown and eventualloss of cartilage (osteoarthritis).