Effectiveness

Osteoarthritis of the knee: controversial, probably effective

Pain in rheumatoid arthritis: limited data, possibly effective

Adverse effects

Common: epigastric pain or tenderness, heartburn, diarrhea, nausea

Severe or rare: potential hypersensitivity (theoretical)

Interactions

Diabetes medications: reduced effectiveness (theoretical)

Warfarin (Coumadin): increased anticoagulation effect

Contraindications*

Allergy to shellfish

Asthma

Use of warfarin or diabetes medications

Dosage

500 mg orally three times daily

Cost†

$9 to $35 for one-month supply

Bottom line

Already widely in use

No clear clinical data for or against use in the indicated conditions, but reasonable to discuss or support a 60-day trial of glucosamine sulfate, especially in patients at high risk of secondary effects from other accepted treatments