Dimethyl sulphoxide and
methylsulfonylmethane are two related nutritional supplements used for symptomatic relief of
osteoarthritis (OA). We conducted a meta-analysis to evaluate their efficacy in reducing
pain associated with OA. Randomized or quasi-randomized controlled trials (RCTs), identified by systematic electronic searches, citation tracking and searches of clinical trial registries, assessing these supplements in
osteoarthritis of any joint were considered for inclusion. Meta-analysis, based on difference in mean
pain related outcomes between treatment and comparator groups, was carried out based on a random effect model. Seven potential trials were identified of which three RCTs, two
DMSO and one MSM (total N = 326 patients) were eligible for inclusion. All three trials were considered high methodological quality. A significant degree of heterogeneity (χ(2) = 6.28, P = .043) was revealed. Two studies demonstrated statistically significant (but not clinically relevant) reduction in
pain compared with controls; with one showing no group difference. The meta-analysis confirmed a non significant reduction of
pain on visual analogue scale of 6.34 mm (SE = 3.49, 95% CI, -0.49, 13.17). The overall effect size of 1.82 was neither statistically nor clinically significant. Current evidence suggests
DMSO and MSM are not clinically effective in the reduction of
pain in the treatment of OA. No definitive conclusions can currently be drawn from the data due to the mixed findings and the use of inadequate dosing periods.