Glucosamine, an endogenous aminomonosaccharide, is a simple molecule found in mucopolysaccharides, mucoproteins, and chitin. It stimulates the synthesis of glycosaminoglycans and proteoglycans, both of which are considered building blocks of the cartilage, and has weak anti-inflammatory effects. Glucosamine may inhibit degenerative enzymes responsible for destruction of the cartilage and appears to be effective in reducing pain and improving range of motion in patients with osteoarthritis. It may also slow the process of joint damage. Glucosamine is available as 500-mg tablets.

Reported uses

Glucosamine is used to treat osteoarthritis.


The average dose is 500 mg by mouth, three times a day. The duration of therapy may be from 2 weeks to 3 months. For obese patients, dose is 20 mg/kg of body weight.


Adverse reactions associated with glucosamine include drowsiness, headache, insomnia, peripheral edema, nausea, vomiting, abdominal pain, diarrhea, tachycardia, bronchopulmonary complications, and skin rash. It may cause increased resistance to hypoglycemics and insulin. Diuretics decrease the effectiveness of glucosamine.

Patients with a history of allergic reaction to glucosamine or any of its components should avoid use. Patients with diabetes mellitus should use with caution.

Clinical considerations

  • Glucosamine may increase the adverse effects of diabetes mellitus.
  • Monitor patient for possible adverse effects such as peripheral edema, tachycardia, drowsiness, headache, insomnia, nausea, vomiting, abdominal pain, diarrhea, and skin rash.
  • Inform patient that the therapeutic and toxic components of glucosamine sulfate can vary significantly from product to product. Advise him to obtain glucosamine sulfate from a reliable source.
  • Advise patient that, although limited drug interactions have been reported with use of this product, more potential interactions may exist.
  • Inform patient that it may take a minimum of 4 to 6 weeks for benefits to be seen.
  • Advise patient to keep the glucosamine sulfate away from children and pets.
  • Tell patient to notify pharmacist of any herbal or dietary supplement that he’s taking when obtaining a new prescription.
  • Advise patient to consult his health care provider before using an herbal preparation because a conventional treatment with proven efficacy may be available.

Research summary

Randomized, placebo-controlled, double-blind studies found that glucosamine is well-tolerated and effective in the treatment of osteoarthritis of the knee. In some studies, pain was reduced, joint flexion abilities were increased, and articular function was restored in patients taking glucosamine, compared with those taking placebo. Investigators concluded that glucosamine rebuilds damaged cartilage, thus restoring articular function in most patients.

At least 15 other studies have shown it to be a safe and effective treatment of various forms of osteoarthritis. Further studies are warranted on various dosage regimens and potential long-term effects.