Herbs & Supplements

Should I take it?

Glucosamine is a molecule that contains both sugar and protein. It is one of the essential components that the body uses in building and repairing tissues such as cartilage, heart valves, mucous membranes, and synovial fluid--the jelly-like substance that fills the joints. Although glucosamine is produced in the body, its natural production slows down as individuals get older. For supplemental use, glucosamine may be made in a laboratory. More often, however, it is obtained from natural sources such as the shells (also called exoskeletons) of crabs, lobsters, and other sea creatures. In addition to its use as a dietary supplement for arthritis, glucosamine is added to sports drinks for athletes and to cosmetics and shampoos.

Dosage and Administration

In the United States, glucosamine is most often taken orally--typically as capsules and usually combined with chondroitin, manganese, vitamin C, or other dietary supplements. Occasionally, different salts of glucosamine may be combined into one product. Although study evidence does not prove that taking glucosamine and chondroitin together is more effective than glucosamine alone, the two products frequently are sold in combination. Less frequently, glucosamine is applied topically--again often in combination with chondroitin. In other countries, glucosamine is available in forms that may be injected into muscles or directly into joints. While injectable glucosamine is not sold in the United States, injectable hyaluronic acid products are available with a prescription.

By mouth, a typical daily dose of glucosamine ranges from 500 mg to 3,000 mg (one-half gram to 3 grams) per day. Many studies used glucosamine sulfate 500 mg three times a day to treat either OA or TMJ pain. Some studies found that doses higher than 1,500 mg (1.5 grams) per day did not provide additional benefit. Full effectiveness in controlling arthritis pain may take up to 4 weeks to develop after glucosamine has been started.

Note: Glucosamine and chondroitin are frequently sold in combination with the trace element manganese, because manganese is thought to be involved in cartilage production. A trace element is a substance that is required by the body in very small amounts for proper growth and functioning. However, care should be taken to limit manganese intake. The upper tolerable limit, which is the maximum amount that probably will not cause any side effects for most individuals taking manganese, has been set by the U.S. National Academy of Sciences at 11 mg per day for adults. Higher amounts of manganese taken for long periods may result in symptoms such as confusion, drooling, hallucinations, memory loss, stiff muscles, trembling, and other symptoms similar to Parkinson's disease.

Summary

The major medical use of glucosamine--alone or with chondroitin--is to relieve joint pain and stiffness associated with osteoarthritis. It may help wounds to heal and some forms of glucosamine may also alleviate inflammatory bowel diseases.

Risks

Taking glucosamine derived from sea creatures may cause allergic responses in individuals who are allergic to shellfish. Individuals with diabetes may experience elevated blood sugar levels if they inject glucosamine, which may also raise blood sugar for individuals who do not have diabetes. Small children and pregnant or breast-feeding women may want to avoid taking glucosamine because little is known about its effects for these individuals.

Side Effects

Gastrointestinal complaints such as constipation, diarrhea, and nausea were attributed to taking glucosamine during studies. Some study participants who took glucosamine sulfate also reported drowsiness or headache.

Interactions

Glucosamine may increase the risk of excessive bleeding when it is taken with warfarin, other anticoagulant or antiplatelet drugs, aspirin, or herbal products that reduce the blood's ability to clot. Injecting it may also increase blood sugar levels, thereby interfering with insulin and drugs or herbals that lower blood sugar.

Last Revised August 9, 2007