Glucosamine and Chondroitin for Knee Arthritis: Do They Work?
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Short answer
The U.S. National Center for Complementary and Integrative Health (NCCIH) says it is "still uncertain" whether glucosamine and chondroitin help knee osteoarthritis symptoms. The 2019 ACR/Arthritis Foundation guideline recommends against both for knee osteoarthritis, while a 2021 AAOS guideline lists them as possibly helpful for mild-to-moderate cases. If you try them, treat it as a time-limited experiment and tell your pharmacist what else you take.
What the research says
Glucosamine and chondroitin are among the most-sold joint supplements in the U.S., so most "joint formula" products on this site contain one or both. Here is what NCCIH reports:
- Symptom relief is unsettled. A 2018 analysis of 29 studies found each supplement alone reduced pain overall, but the combination did not, and individual studies disagreed with each other.
- No structural benefit in the big NIH-funded trial. In a 2-year U.S. study of 572 people, joint space width did not differ between placebo and any treatment group (glucosamine, chondroitin, both, or celecoxib).
- Guidelines disagree. The 2019 ACR/Arthritis Foundation and OARSI guidelines recommend against both for knee osteoarthritis; the 2021 AAOS guideline lists them as possibly helpful for mild-to-moderate disease.
- Safety looks acceptable for most people. NCCIH says no major safety problems have been identified in large studies, but glucosamine may raise blood sugar in some people.
Who should check first
- Anyone on warfarin. NCCIH reports both supplements have been associated with an increased risk of bleeding in people taking this blood thinner. Ask your prescriber or pharmacist before starting.
- People with diabetes or blood-sugar concerns, because of the blood sugar note above.
- People with shellfish allergy. Many glucosamine products are made from shellfish shells. NCCIH does not discuss this, so read the label's source line and ask your pharmacist.
- Pregnant or breastfeeding women. NCCIH says little is known about safety.
How to run a fair 8 to 12 week trial
- Write down your pain on a 0 to 10 scale for walking, stairs and sleep before you start.
- Change only one thing at a time, so you know what caused any difference.
- Keep your receipt and note the refund deadline. Our guarantee comparison lists refund windows for 20 products.
- Re-score after 8 to 12 weeks. If nothing changed, stop and ask your doctor about exercise, physical therapy, weight management or topical options.
How this affects the products we review
Several joint supplements we cover list glucosamine or chondroitin among their ingredients (for example Joint Advance). Brand claims about these ingredients come from the makers, not from independent trials, so judge any product by the refund terms and your own tracked results.
Frequently asked questions
Do glucosamine and chondroitin work for knee arthritis?
NCCIH says it is still uncertain. A 2018 analysis found mixed results, and the 2019 ACR/Arthritis Foundation guideline recommends against both for knee osteoarthritis.
Is glucosamine safe with warfarin?
NCCIH reports that glucosamine and chondroitin have been associated with an increased risk of bleeding in people taking warfarin. Ask your prescriber or pharmacist before starting.
Can glucosamine raise blood sugar?
NCCIH notes glucosamine may raise blood sugar in some people. If you have diabetes, ask your doctor before trying it.
How long should I try a joint supplement?
A common approach is 8 to 12 weeks while tracking your pain scores, then stopping if nothing has changed. Keep your receipt for the refund window.
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Sources
This page is general information, not medical advice. Talk to your doctor or pharmacist before starting or changing any treatment, especially if you take prescription medication.