Level 2: Mid-level evidence
Glucosamine and chondroitin, alone and in combination, have become popular as both prescription and OTC supplements for joint pain. A recent systematic review of 10 randomized trials evaluated their efficacy in 3,803 patients with hip or knee osteoarthritis. The review excluded trials with fewer than 100 patients in each arm. Neither supplement was found to produce clinically significant reductions in pain in any formulation. In all studies, pain was measured on a 10-cm visual analog scale, with a change of ≥0.9 cm deemed clinically significant. The mean reductions compared to placebo were 0.4 cm (95% CI -0.7 to -0.1 cm) for glucosamine alone in analysis of seven trials, 0.3 cm (95% CI -0.7 to 0 cm) for chondroitin alone in analysis of four trials, and 0.5 cm (95% CI -0.9 to 0 cm) for the combination in one trial. There were no significant differences in adverse events in comparisons of either drug to placebo.
In an earlier review of 25 randomized trials with significant statistical heterogeneity, there was inconsistent evidence for pain relief with glucosamine, but there was no significant improvement in an analysis of 11 trials that had adequate allocation concealment.