Benefits
Osteoarthritis pain and function
Several small randomized trials in knee osteoarthritis report modest improvements in pain or physical function with MSM, but a meta-analysis of the best-designed trials found the pooled effect on pain did not reach statistical significance. Effect sizes are small, and MSM is best viewed as optional adjunct support rather than a proven treatment.
Exercise soreness and recovery
In two small trials (a half-marathon study in 22 runners and an 8-person pilot), MSM did not significantly reduce blood markers of muscle damage (creatine kinase, lactate dehydrogenase) or oxidative stress. Runners taking MSM reported less post-exercise muscle and joint soreness, but the difference did not reach statistical significance.
Sulfur for connective tissue
MSM provides bioavailable sulfur required for joint cartilage, collagen, and other connective tissues. Mechanism contributes to its joint health applications and supports overall structural tissue maintenance.
Anti-inflammatory activity (mechanistic)
Anti-inflammatory activity is seen in animal and cell studies, but human oral-MSM trials have not demonstrated reductions in blood inflammatory markers such as CRP or IL-6. Any anti-inflammatory benefit in people remains unproven.
Skin, hair, and nails (limited evidence)
Sulfur is a building block for keratin (hair and nails) and collagen (skin), but there are no controlled trials of oral MSM for skin, hair, or nail outcomes. The only clinical skin study used a topical cream combining MSM with silymarin, which does not show what oral MSM does.
Sulfur and glutathione (mechanism only)
MSM supplies sulfur that the body can use in glutathione synthesis, but human trials that measured glutathione and oxidative-stress markers did not find consistent improvement, so a meaningful antioxidant effect in people is not established.
Combination with glucosamine
In one randomized trial, MSM combined with glucosamine reduced knee osteoarthritis pain and swelling more than either agent alone over 12 weeks. That trial did not include chondroitin, so combinations adding chondroitin are less directly supported.
Strong safety and tolerability
Well-tolerated across long-term clinical trials with side effects no more frequent than placebo. Suitable for chronic use — an important consideration for ongoing joint health support where NSAID alternatives matter.
Mechanism of action
Sulfur donation
MSM provides bioavailable sulfur, used in synthesis of glutathione, methionine, cysteine, and sulfur-containing structural proteins (keratin, collagen). Supports antioxidant capacity via glutathione regeneration. Foundation for skin/hair/nail and antioxidant applications. Note: typical Western diets are not sulfur-deficient — supplementation provides marginal benefit in well-nourished adults.
Anti-inflammatory signaling
MSM modulates NF-κB signaling and reduces inflammatory cytokines (TNF-α, IL-6) in animal and cell studies. No human trial of oral MSM has shown a reduction in CRP or IL-6, so this is mechanistic, not a demonstrated human effect. Mechanism plausible but clinical effect sizes modest compared to mechanism-based predictions.
Antioxidant via glutathione support
MSM supports endogenous glutathione synthesis through cysteine donation. Glutathione is the primary intracellular antioxidant. May reduce exercise-induced and inflammatory oxidative stress markers.
Mucolytic activity (allergic rhinitis context)
MSM may have mild mucolytic effects, reducing mucus viscosity. Possible mechanism for upper respiratory symptom relief in seasonal allergic rhinitis. Not as well-characterized as anti-inflammatory mechanism.
Possible mast cell stabilization
Proposed mechanism for allergic rhinitis benefit — MSM may stabilize mast cells and reduce histamine release. Mechanism would explain symptom relief without sedation seen in MSM trials. Direct evidence from human studies limited; remains hypothetical.
Clinical trials
Evidence review and pooled analysis of MSM and DMSO for osteoarthritis pain.
Clinical population described in trial publication.
Evidence review and pooled analysis of MSM and DMSO for osteoarthritis pain. 3 high-quality clinical trials (2 DMSO, 1 MSM, total N=326). Pooled VAS pain reduction 6.34 mm (95% CI -0.49 to 13.17) — neither statistically nor clinically significant. Effect size 1.82. Major honesty correction to popular MSM-for-arthritis marketing — most rigorous meta-analytic evidence is null.
Single-blind clinical trial in 118 patients with mild-moderate knee OA.
118 patients with mild-moderate knee OA
Randomized, double-blind, placebo-controlled trial in 118 patients with mild-moderate knee OA. Four arms: glucosamine 500mg, MSM 500mg, the combination, and placebo, three times daily for 12 weeks. MSM alone, glucosamine alone, and the combination all improved symptoms versus placebo, with the combination giving the largest and fastest improvement (measured by pain index, VAS, and the Lequesne index, not WOMAC). Used lower MSM dose than typical supplemental practice; results may underestimate full-dose effect.
Multicenter open-label trial in 50 subjects with SAR. MSM 2,600 mg/day × 30 days.
50 subjects with SAR
Multicenter open-label trial in 50 subjects with SAR. MSM 2,600 mg/day × 30 days. Significant reductions in upper respiratory symptoms (runny nose, congestion, sneezing) by day 7 (p<0.01). Lower respiratory symptoms also improved by week 3. Effects sustained throughout 30-day trial. Open-label design limits causal inference but signal substantial enough to motivate randomized follow-up.
Randomized double-blind exploratory study with standardized allergen challenge methodology.
Clinical population described in trial publication.
Randomized double-blind exploratory study with standardized allergen challenge methodology. This small exploratory study had every participant take MSM at different daily doses (1, 3, or 6 g/day) with no placebo group, comparing symptoms against each person's own baseline after an allergen challenge. Nasal symptoms fell and peak nasal inspiratory flow rose, most at 3 g/day, but without a placebo arm the findings are preliminary. Objective measure: improved peak nasal inspiratory flow. Better-quality follow-up to the 2002 open-label trial; joint and exercise-recovery remain MSM's better-evidenced uses.
Double-blind randomized trial of topical silymarin + MSM cream vs vehicle in mild-moderate rosacea × 30 days.
Clinical population described in trial publication.
Double-blind randomized trial of topical silymarin + MSM cream vs vehicle in mild-moderate rosacea × 30 days. Improvements in papules, erythema, itching, skin hydration. Combination intervention — independent MSM contribution to effect unclear. This is a topical, combination product (silymarin plus MSM cream) — a different delivery route from oral MSM — so it does not establish an oral-MSM skin benefit.