Side effects came at about the same rate as on a dummy pill
Cochrane put the risk of an adverse reaction on glucosamine at about placebo's, and found no excess of side effects or withdrawals across 43 chondroitin trials.
What the study found
Glucosamine and chondroitin matched placebo on side effects
Cochrane put the risk of an adverse reaction on glucosamine at about the same as placebo, and found no excess of side effects or withdrawals across 43 chondroitin trials. In the long trials serious events were rare and evenly spread. What they mostly do is nothing, in both directions.
The caveat · Not built to catch rare harms
None was designed to detect rare harm, and the participants were people with knee osteoarthritis, not the general population. The chondroitin review's finding of fewer serious events on treatment than on placebo more likely reflects sparse, inconsistently reported data than a real effect.