Glucosamine – what are the adverse effects?

Eimear Maguire, Senior Medicines Information Pharmacist, North West Medicines Information CentrePublished


  • Glucosamine supplements are widely used for relieving pain and symptoms associated with osteoarthritis. They appear to be well tolerated, with a reported frequency of adverse effects similar to that with placebo.
  • Mild gastrointestinal disturbance is the most common adverse effect. Other adverse effects include headache, drowsiness, insomnia and skin reactions.
  • Glucosamine supplements are either produced synthetically or derived from the shells of shellfish, and should not precipitate allergic reactions in patients sensitive to shellfish. However, some sources contraindicate or recommend cautious use of these products in patients allergic to shellfish.
  • Glucosamine does not appear to adversely affect plasma blood glucose in patients without diabetes. However, data relating to its effects in patients with diabetes are lacking. It would be prudent for patients with diabetes to monitor their blood glucose levels more closely if they start to take glucosamine, increase their dose or change the product taken.
  • There are a few case reports of hepatotoxicity related to glucosamine, but the mechanism for this has not been established. If a patient develops increased liver enzymes, consider stopping glucosamine because of the risk of developing more severe liver injury with continued use.
  • Glucosamine should be used with caution in patients with renal impairment or those taking nephrotoxic medications.