Chondroitin sulfate is a natural component of cartilage. It is extracted from shark or cow cartilage or manufactured synthetically. It is frequently combined with glucosamine.
People most often take chondroitin sulfate by mouth for osteoarthritis. For arthritis, it is frequently taken along with glucosamine (see Glucosamine). Scientific evidence shows no benefit when chondroitin sulfate is taken by itself. However, evidence suggests that combined with glucosamine, it may reduce joint pain and improve joint mobility.
Chondroitin sulfate seems to have no serious side effects. Among the most common side effects are stomach pain, nausea, and other digestive tract symptoms. Other side effects include heart rate problems and swelling.
Chondroitin sulfate may also affect the action of drugs that prevent blood clots (anticoagulants) such as warfarin. Chondroitin sulfate is safe for most, but people who have asthma, blood-clotting disorders, or prostate cancer should use caution when taking it.