It may take at least 4 weeks of taking glucosamine consistently before you notice any improvement. If your symptoms worsen while taking glucosamine, contact your health care provider.
Glucosamine appears to be safe for most people. Common side effects include cramping, gas, nausea, heartburn, diarrhea, and constipation. Rare side effects include severe allergic reactions and liver damage.
Do not take glucosamine if you are taking an anticoagulant medication such as warfarin. Glucosamine may increase the effect of warfarin and the risk of bleeding. Glucosamine may interact with a class of cancer medications called topoisomerase II inhibitors (e.g., etoposide, doxorubicin).
Since glucosamine is produced from shells of shrimp, lobster, and crab, people with shellfish allergy should avoid it.
You should consult a health care practitioner before taking glucosamine if you have asthma, glaucoma, or are pregnant or breast-feeding.
Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.