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by Ara DerMarderosian, PhD

Glucosamine is a precursor of multiple cartilage constituents. It is extracted from chitin (in shells of crabs, oysters, and shrimp) and is taken in tablet or capsule form, usually as glucosamine sulfate, but sometimes as glucosamine hydrochloride. Glucosamine is often taken with chondroitin sulfate (see Chondroitin Sulfate).


Strong scientific evidence supports use of glucosamine sulfate for treatment of mild to moderate osteoarthritis of the knee. Its role in the treatment of more severe knee osteoarthritis and osteoarthritis in other locations is less well-defined. Some evidence suggests it has both analgesic and disease-modifying effects, whereas evidence from other large and well-designed studies shows it to be of no benefit. One very large study showed that glucosamine hydrochloride is beneficial only when combined with chondroitin sulfate. Mechanism is unknown but may be related to improved glycosaminoglycan synthesis as a result of the sulfate moiety. Dose is 500 mg po tid.

Adverse effects

Allergy (in patients who have shellfish allergy and take forms extracted from shellfish), dyspepsia, fatigue, insomnia, headache, photosensitivity, and nail changes may occur.

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