Experts agree that a daily 1,500 mg dose of glucosamine sulfate is generally safe and well tolerated—the main exception being for pregnant and nursing mothers. Some studies show benefits in reducing joint pain and improving function, while others have failed to show any value. Stick with national brands when selecting a product, and make sure you’re buying glucosamine sulfate, rather than glucosamine hydrochloride. (The latter formula needs more clinical testing.)
As always, ask your doctor or pharmacist about potential interactions with prescription medicines before starting any new supplement.