Nausea may occur at intakes greater than 10 grams per day. No other adverse effects have been reported.

One doctor has raised a concern that chondroitin sulfate should not be used by men with prostate cancer. This concern is based upon two studies. In one, the concentration of chondroitin sulfate was found to be higher in cancerous prostate tissue as compared to normal prostate tissue.³ In the other study, it was shown that higher concentrations of chondroitin sulfate in the tissue surrounding a cancerous prostate tumor predict a higher rate of recurrence of the cancer after surgery.⁴ However, no studies to date have addressed the question of whether taking chondroitin sulfate supplements could promote the development of prostate cancer. Simply because a substance is present in or around cancerous tissue does not by itself suggest that that substance is causing the cancer. For example, calcium is a component of atherosclerotic plaques that harden the arteries; however, there is no evidence that taking calcium supplements causes atherosclerosis. To provide meaningful information, further studies would need to track the incidence of prostate cancer in men taking chondroitin supplements. Until then, most nutritionally-oriented doctors remain unconcerned about this issue.