MSM (Methylsulfonylmethane)
Sulfur compound taken for joint pain, with small, inconsistent effects.
What is MSM (Methylsulfonylmethane)?
MSM (Methylsulfonylmethane) is a joint and skin supplement used for ease knee osteoarthritis pain. NutriDex grades the human evidence as Mixed. MSM is an organic sulfur compound (dimethyl sulfone) sold mainly for joint pain. In knee osteoarthritis, two 12-week placebo-controlled RCTs found statistically significant but small improvements in WOMAC pain and physical function at 3–6 g/day, and a 2023 trial at 2 g/day improved a Japanese knee-OA score (8.1 vs 10.9 points). However, a 2009 meta-analysis of three good-quality trials (326 patients) found only a non-significant 6.3 mm reduction in pain on a visual analogue scale, concluding MSM and DMSO are not clinically effective. In exercise studies, MSM blunted post-run muscle and joint soreness but did not lower oxidative-stress or muscle-damage markers. One open-label trial suggested relief of seasonal allergic-rhinitis symptoms, but it had no placebo group. Overall the effects are inconsistent and likely minor; MSM is well tolerated but not a proven treatment.
Purported Benefits
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
| Outcome | Evidence | Effect | Studies |
|---|---|---|---|
| Ease knee osteoarthritis painIndividual RCTs show small WOMAC/JKOM gains, but a meta-analysis of 3 trials found a non-significant 6.3mm VAS drop. | Mixed | ↔ mixed · small | 3 |
| Improve physical functionTwo 12-week knee-OA RCTs improved function vs placebo, but effects were small and trials short. | Preliminary | ↑ benefit · small | 2 |
| Reduce post-exercise sorenessOne small half-marathon RCT blunted muscle/joint pain but did not change muscle-damage or oxidative markers. | Preliminary | ↑ benefit · small | 1 |
| Relieve allergic rhinitisSingle open-label trial reported symptom relief, but had no placebo control, limiting interpretation. | Preliminary | ↑ benefit | 1 |