By David Borenstein MD, Medically Reviewed by Dr. C.H. Weaver M.D. 11/2021
Glucosamine and chondroitin sulfate are substances found naturally in the body. Glucosamine is an amino sugar that plays a role in cartilage formation and repair. Chondroitin sulfate is part of human cartilage. Cartilage is the firm, slippery and rubbery material that covers the surface of bones and allows for smooth joint movement.
Both glucosamine and chondroitin sulfate are sold separately or combined as dietary supplements, usually in the form of a pill. Glucosamine in supplements commonly comes from shellfish, although there is now a non-shellfish glucosamine that is made from a fungus. Glucosamine comes in either sulfate or hydrochloride form. Chondroitin sulfate is usually taken from the cartilage of cattle tracheas (windpipes), but can also be derived from pig or shark cartilage.
Why Are Glucosamine and Chondroitin Sulfate Used to Treat Arthritis?
These supplements have been used to treat osteoarthritis, or OA, in horses and dogs for many years. In Europe, people have used glucosamine and/or chondroitin sulfate to treat OA in humans since the 1980s. For more than a decade, people in the United States have used these supplements in an attempt to manage their osteoarthritis. They are only intended for use by people with OA. Glucosamine and chondroitin sulfate are not intended for use by patients with rheumatoid arthritis, gout, lupus or other related diseases.
What Do Glucosamine and Chondroitin Sulfate Do?
A number of well designed clinical studies have been done mostly in Europe to determine the effectiveness of glucosamine and chondroitin, and the results are mixed. Several studies have demonstrated some degree of pain relief and improved joint function in people with mild to moderate OA who took these supplements. Other studies have shown no benefit at all.
In studies where the supplements were reported to work, results showed they provided pain relief at a level similar to that of nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin) and naproxen sodium (Aleve). However, more recent studies performed in North America and the United Kingdom haven’t confirmed these benefits.
Two studies performed by a manufacturer of glucosamine sulfate supplements suggest that glucosamine sulfate may be helpful for not only relieving pain but also for slowing cartilage loss in people with knee OA. Two studies performed by another manufacturer have suggested that chondroitin sulfate may slow cartilage loss in people with knee OA.
The National Institutes of Health (NIH) recently completed the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), a long-term clinical study of glucosamine hydrochloride and chondroitin sulfate in people with OA of the knee. The study looked at two specific issues: whether glucosamine and/or chondroitin could treat the pain of OA in the knee, and whether the dietary supplements could help reduce damage and slow the breakdown of cartilage surrounding the knee.
The study concluded that taking glucosamine hydrochloride and chondroitin sulfate was no better than taking a placebo (a pill that contains no medicine) in reducing pain in the majority of people with OA. The study also concluded that there was virtually no difference in cartilage breakdown between people who took the supplements for the study and those who did not.
The study also found that the combination of the two supplements provided significant pain relief for a smaller group of people with moderate-to-severe knee OA.
Based on these findings, taking a combination of glucosamine hydrochloride and chondroitin sulfate may be a beneficial part of an overall treatment plan for people with moderate-to-severe knee OA. Patients considering taking these supplements should speak with their doctor first and remain on any current prescribed medications.
How Should Glucosamine and Chondroitin Sulfate be Taken?
It’s recommended that you take the amount that has been used in most clinical studies, which is 1,500 milligrams (mg) of glucosamine (2,000 mg for people who weigh more than 200 pounds) and 1,200 mg of chondroitin sulfate daily. As a general rule, take the dose recommended on the bottle because tablet concentrations of the supplements may vary from brand to brand.
Some physicians may recommend that glucosamine be taken as a single 1,500 mg dose at one time, rather than dividing the dose during the day. If that relieves your symptoms, you may be able to gradually decrease the amount you take after a few months. Your doctor may also suggest that glucosamine and chondroitin sulfate be taken together for maximum benefit.
The length of time necessary to evaluate the supplements’ effect is generally a minimum of six to eight weeks, however a full trial of 12 weeks may be necessary. During this time, you should take the supplements with your current medications. If there’s improvement in your pain, talk to your doctor about decreasing or stopping your other medicines for a while to see if there is a change in pain and stiffness levels.
If you don’t notice any difference in your symptoms after taking the supplements for three to six months, you probably will not get any relief and should discontinue use. Some people may get some relief by using the supplements, but they may still have to take their other medications for full relief.
Glucosamine and chondroitin sulfate cannot cure OA, and they are not a replacement for an all-around treatment regimen that includes other medications your doctor may subscribe, regular exercise and lifestyle modification.
Are There Side Effects From Glucosamine and Chondroitin Sulfate?
The most common side effects of glucosamine and chondroitin sulfate are indigestion and nausea. Diarrhea, constipation, vomiting or heartburn may also occur. Significant adverse events have not been associated with long-term use of glucosamine and chondroitin sulfate. Be sure to talk to your doctor if you notice any unusual or new symptoms while taking glucosamine and/or chondroitin sulfate.
Although not enough studies have been done on glucosamine and chondroitin sulfate to know all of the necessary precautions, it is well known that certain people should be careful when considering taking these supplements.
Children and women who are pregnant, breastfeeding or who plan to become pregnant should not take these supplements.
Glucosamine is an amino sugar that may affect sugar metabolism, so people who have diabetes should check their blood sugar levels more often if they take this supplement.
If you are taking chondroitin sulfate and a blood-thinning medication, have your prothrombin time (PT) checked more often. Some supplements may contain components similar to the blood-thinning drug heparin. This combination could increase the risk of bleeding.
If you are allergic to shellfish, talk to your doctor before taking glucosamine. Also, beware that glucosamine and chondroitin sulfate are classified as dietary supplements and, as such, are not strictly regulated by the Food and Drug Administration (FDA). The FDA does monitor labeling but doesn’t authorize or test dietary supplements. This means concentrations of these ingredients in supplements may vary from brand to brand and may not be precise. With all supplements, manufacturers and consumers are responsible to check safety. Talk to your doctor for guidance.
Tips for Taking Glucosamine and Chondroitin Safely
Glucosamine comes in several forms called salts, usually either glucosamine sulfate or glucosamine hydrochloride.
Shark cartilage products contain chondroitin sulfate, but the quality and quantity of chondroitin sulfate in them are inconsistent.
Dietary supplements are not strictly regulated by the FDA, Their quality and content may vary widely. If you decide to take these supplements:
• Choose products sold by large, well-established companies.
• Read the product labels carefully. Make sure the ingredient lists make sense to you. If you have trouble, ask your pharmacist for help.
• Keep in mind that recommended doses should cost about $1 to $3 per day, and most insurance companies do not cover this cost.