Glucosamine and Chondroitin work well for many people but there a few side effects to be aware of. If you are diabetic, have your glucose checked often if you take glucosamine as it could go up. If you use anticoagulants such as aspirin or coumadin, chondroitin may affect clotting times. Lastly, allergies to shellfish could be a problem with glucosamine as it is made from crab and shrimp shells.