Glucosamine Side Effects

Updated April 17, 2017

Glucosamine, also known as glucosamine sulphate, is a nutritional supplement commonly taken for osteoarthritis and other joint complications. Glucosamine is a compound found naturally in cartilage. This is an over-the-counter supplement that many people take it for various conditions and have positive results with few side effects.


Glucosamine is an amino sugar, meaning it is similar to a sugar but has an amino group (-NH2) in place of a hydroxyl group (-OH). Since glucosamine is a synthetic version of a natural compound, the body is able to absorb it with minimal side effects.


Supplemental glucosamine can enhance the ability of cartilage cells, called chondrocytes, to increase the production of molecules for the extracellular matrix. These molecules, called hyaluronan and proteoglycans, give the cartilage its shock-absorbing properties. If the production of these molecules is compromised, the cartilage can become damaged. This function of glucosamine makes it a candidate to help in treating osteoarthritis, especially of the knee. Other conditions that may benefit from glucosamine supplementation (more research is necessary) are chronic venous insufficiency, rheumatoid arthritis and temporomandibular (jaw) joint disorders.

Side Effects

Common side effects of supplemental glucosamine are upset stomach, headache, insomnia, drowsiness, skin reactions and sensitivity to sun. More severe side effects include vomiting, nausea, diarrhoea, stomach pain, loss of appetite, constipation and flatulence. These more severe side effects are rare, but if encountered, you should discontinue use and contact your doctor. In a very few cases, patients have reported temporary increases in blood pressure and heart rate and even palpitations.


Always consult a doctor before taking any medication, even dietary supplements. Patients with diabetes should use caution, as the effect of glucosamine on insulin levels is not yet well known. Also, patients with kidney problems should use caution because glucosamine is eliminated in the urine and can cause increased protein levels in the urine. Those with abnormal kidney function may eliminate glucosamine from the body more slowly, thereby causing more issues. Women who are pregnant or breast feeding should not take glucosamine as there is not enough research to determine the effects on the foetus.


Supplemental glucosamine may be made using the shells of shellfish, including shrimp, crabs and others. Those who are allergic to shellfish, or have sensitivity to iodine, should use caution when taking glucosamine. Some studies suggest that the amount of shellfish present in the glucosamine supplement is so small that it will not trigger an allergic reaction, but caution should still be used. Symptoms of an allergic reaction may include swelling of the throat. Glucosamine has also been reported to exacerbate asthma symptoms.

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About the Author

Stephanie Chandler is a freelance writer whose master's degree in biomedical science and over 15 years experience in the scientific and pharmaceutical professions provide her with the knowledge to contribute to health topics. Chandler has been writing for corporations and small businesses since 1991. In addition to writing scientific papers and procedures, her articles are published on and other websites.