Glucosamine is a dietary supplement that is often combined with another supplement, chondroitin, to treat osteoarthritis. Glucosamine is made from the shells of shellfish and chondroitin is derived from cow trachea.
Evidence published in the New England Journal of Medicine in 2006 suggested that glucosamine alone or combined with chondroitin can help relieve osteoarthritis pain in a subgroup of people with moderate to severe knee osteoarthritis.
It should be noted that based on further research, the American Academy of Orthopedic Surgeons currently advises against the use of glucosamine sulfate, chondroitin sulfate, and glucosamine hydrochloride in treating symptomatic knee osteoarthritis.
Supplements advertised for improved joint health can be confusing and even downright misleading. Because supplements don’t undergo the rigorous testing that pharmaceutical drugs do, the “recommended” dose is less supported by hard clinical evidence. And that can be a problem.
If you take too little, you won’t achieve a beneficial effect and you are essentially wasting your money. If you take too much, you may be increasing the risk of side effects.
Results of a study from Tufts-New England Medical Center conclude that typical doses listed on over-the-counter supplements are probably not strong enough to help relieve arthritic joint pain and stiffness.
To this end, the recommended dosages are based more on what amount of drug causes little to no harm yet is believed to offer therapeutic benefits.
The initial dose is typically 1,500 milligrams [mg] of glucosamine and 1,200 mg of chondroitin daily for one to two months. If a response is obtained, the dose can be reduced to 1,000 mg of glucosamine and 800 mg of chondroitin per day.
According to the Tufts study, it is still unclear as to whether higher doses are more effective and whether that level of dosing may cause potential harm.
Illustration by Cindy Chung, VerywellBecause supplements are not regulated by the Food and Drug Administration, the amount of active ingredient cannot always be verified.
Most studies have shown that glucosamine needs to be taken for two to four months before its full benefits are realized, although some will experience improvement sooner.
Potential side effects of glucosamine-chondroitin include:
- Nausea
- Diarrhea
- Constipation
- Stomach pain
- Gas and bloating
- Puffy eyes
- Hair loss
These risks may increase at higher doses. Glucosamine should be avoided if you are allergic to shellfish. People on the blood thinner Coumadin [warfarin] may have an increased risk of bleeding.
Stop treatment and call your healthcare provider if you experience sudden swelling in the legs or irregular heartbeats. Call 911 or seek emergency care if you develop hives, shortness of breath, rapid heartbeats, or the swelling of the face, tongue, or throat.
Always consult your own healthcare provider. Your healthcare provider knows your medical history and your current medication regimen. Make your healthcare provider aware that you wish to add a supplement to your treatment regimen, then follow their advice.
Frequently Asked Questions
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Does glucosamine and chondroitin work for knee pain?
For some people, yes. One notable 2016 study of glucosamine and chondroitin found the supplement combo helps to reduce pain, stiffness, functional limitations, and joint swelling as effectively as the prescription anti-inflammatory drug Celebrex [celecoxib].
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Are glucosamine and chondroitin safe?
In general, yes, glucosamine and chondroitin are safe to take in doses listed on the supplement label. However, people who are allergic to shellfish should not take glucosamine. In addition, taking this supplement with the blood thinner Coumadin [warfarin] may increase the risk of bleeding.
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Do glucosamine and chondroitin have side effects?
Yes. Glucosamine and chondroitin can cause gastrointestinal side effects, such as bloating, constipation, diarrhea, gas, nausea, and stomach pain. The supplement combo may also cause puffy eyes and hair loss.
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Clegg DO, Reda DJ, Harris CL, et al. Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis. N Engl J Med. 2006;354[8]:795-808. doi:10.1056/NEJMoa052771
American Academy of Orthopedic Surgeons. Treatment of osteoarthritis of the knee.
Biggee BA, Blinn CM, McAlindon TE, et al. Low levels of human serum glucosamine after ingestion of glucosamine sulphate relative to capability for peripheral effectiveness. Ann Rheum Dis. 2006;65:222-226. doi:10.1136/ard.2005.036368
Dahmer S, Schiller RM. Glucosamine. Am Fam Physician. 2008;15;78[4]:471.
Hochberg MC, Martel-Pelletier J, Monfort J, et al; MOVES Investigation Group. Combined chondroitin sulfate and glucosamine for painful knee osteoarthritis: a multicentre, randomised, double-blind, non-inferiority trial versus celecoxib. Ann Rheum Dis. 2016;75[1]:37-44. doi:10.1136/annrheumdis-2014-206792