Description: Glucosamine and chondroitin are substances that occur naturally in the body. Taken as supplements, they can help relieve arthritic joint pain.

Glucosamine is an amino sugar that's believed to help cartilage formation and repair, the Arthritis Foundation says. And chondroitin sulfate can help give cartilage elasticity.

But the supplements aren't recommended for everyone, the Arthritis Foundation says. Among those who should take great care or avoid them altogether:

Children, pregnant women, and women who may become pregnant.
Diabetics, who should be careful when taking these supplements, as the amino sugars can cause blood glucose levels to rise.
People who are taking blood-thinning medications, since these substances can trigger blood thinning.
People who are allergic to shellfish, from which these supplements often are extracted.