What drugs and foods interact with glucosamine?

Glucosamine supplements can interact with several drugs, increasing or decreasing their effectiveness. These drugs include:

• anticoagulants, such as warfarin (Coumadin)
• chemotherapy drugs, such as doxorubicin, etoposide and teniposide
• acetaminophen (Tylenol)
• blood sugar medications, such as tolbutamide (Orinase), rosiglitazone (Avandia), chlorpropamide (Diabinese) and insulin

Glucosamine is known to boost warfarin's effect, and there have been reports of bruising or bleeding in people taking both, but other interactions are not well established. Some people have no problem taking, say, acetaminophen with their glucosamine. Even so, always ask your doctor about whether it's safe to take glucosamine with other medications. If you have diabetes and take insulin, for instance, you'll be cautioned to keep an even closer eye on your blood sugar while taking glucosamine.

Your doctor or pharmacist can also tell you if a glucosamine supplement contains other ingredients that you should avoid. For example, some supplements contain potassium, which could cause problems if you take a potassium-sparing diuretic, such as spironolactone (Aldactone). In that case, you should choose another type of glucosamine.