DMSO vs MSM: Related Compounds, Different Uses and Risks

MSM is the compound sold as an oral joint-health supplement; DMSO is not a stronger or interchangeable version of it. DMSO has a specific prescription use inside the bladder and has also been studied on the skin for pain. Neither compound has convincing evidence of reliable osteoarthritis relief: NCCIH’s public assessment, last updated in September 2017, says the research is too limited to determine whether either helps.

The useful comparison is therefore not simply “which works better?” It is whether the evidence matches the condition, ingredient and route you are considering.

The differences that matter

Question	DMSO	MSM
Full name	Dimethyl sulfoxide	Methylsulfonylmethane, also called dimethyl sulfone
Main consumer comparison	Topical products promoted for pain	Oral supplements promoted for joint comfort
Relevant human research	Topical formulations for osteoarthritis; prescription bladder treatment for interstitial cystitis symptoms	Small oral trials measuring knee osteoarthritis pain and function; a trial in otherwise healthy adults with mild knee pain
What an amount means	Concentration alone does not specify the total exposure; volume, route and formulation matter	Trials report milligrams or grams taken daily
Distinctive safety issue	Skin penetration, potential effects on other medications, irritation and garlic-like taste or odor	Digestive upset, rashes or allergic reactions; limited long-term safety evidence

These distinctions are described in the NCCIH comparison, the RIMSO-50 prescription label, a review of DMSO and MSM research and the trials below.

Related does not mean equivalent

MSM is an oxidized form of DMSO. Commercial MSM can be produced by oxidizing DMSO and then purifying the resulting compound. Manufacturing review The human body also converts some DMSO into dimethyl sulfone, as the RIMSO-50 label explains.

That relationship does not establish equivalent doses, effects or safety. Taking MSM directly is a different exposure from using DMSO, which is itself absorbed and produces other metabolites. Manufacturing chemistry does not make a finished MSM supplement the same substance as its DMSO starting material. See how commercial MSM is produced for that separate question.

Which has better evidence for joint pain?

Oral MSM has shown some positive results in small knee osteoarthritis trials. Topical DMSO evidence is mixed, including a much larger trial in which a DMSO-containing vehicle did not outperform placebo. These are separate placebo comparisons—not proof that MSM beats DMSO head-to-head.

MSM: a possible symptom benefit, not an established treatment

Two informative osteoarthritis trials illustrate both the promise and the limitations:

• Kim and colleagues, 2006: Fifty adults with knee osteoarthritis entered a randomized, double-blind trial of MSM or placebo for 12 weeks. The target MSM dose was 3 g twice daily, totaling 6 g/day, reached after a first-week increase. MSM improved questionnaire measures of pain and physical function compared with placebo, but not stiffness or the combined symptom score. The authors said the pilot could not confirm long-term benefits or safety. Original trial
• Debbi and colleagues, 2011: Fifty adults with knee osteoarthritis were assigned to 1.125 g three times daily, totaling 3.375 g/day, or placebo for 12 weeks. Physical function and the total WOMAC symptom score favored MSM, but WOMAC pain and stiffness did not differ significantly. A separate pain scale was reported to favor MSM. The authors described improvements as small and of uncertain clinical importance. Assignment alternated by enrollment order, and the groups differed at baseline—limitations that reduce confidence in the findings. Original trial

These findings concern symptoms in knee osteoarthritis. They do not establish cartilage regrowth, a cure, or benefit for every cause of joint pain. The studied amounts are research exposures, not a recommended regimen or a personal safety limit.

A 2023 trial also tested 2 g/day for 12 weeks in 88 otherwise healthy Japanese adults with mild knee pain. Among the 80 participants included in the efficacy analysis, MSM produced a better knee-related questionnaire score than placebo at 12 weeks. However, the between-group difference in change from baseline for that total score was not significant. This was a different population from diagnosed knee osteoarthritis, and the study did not compare MSM with DMSO. Original trial

DMSO: distinguish the ingredient from the drug it carries

In a 775-person, 12-week randomized trial, researchers compared topical diclofenac in a DMSO-containing vehicle with placebo, the DMSO vehicle alone, oral diclofenac and combined topical/oral diclofenac. Topical diclofenac improved symptoms, but the DMSO vehicle was no more effective than placebo. Original trial abstract

This matters when a seller cites research on a “DMSO-containing treatment.” A successful diclofenac formulation does not demonstrate that DMSO alone relieves arthritis pain. Conversely, this one trial does not resolve every DMSO formulation or pain condition; the formulation-specific DMSO pain review examines that distinction.

Uses, forms and doses cannot be transferred

For interstitial cystitis symptoms, DMSO has a defined medical role. In the United States, RIMSO-50 is a sterile prescription 50% w/w aqueous DMSO solution placed directly into the bladder. Its label states that it is approved for symptomatic relief of interstitial cystitis and has not been approved as safe and effective for another indication. This is not approval of retail DMSO for joint pain, skin application or ingestion. Prescription label, revised March 2021

MSM’s dietary-supplement status is different. The FDA does not approve dietary supplements for safety and effectiveness before sale. Availability is therefore not evidence that an MSM product treats osteoarthritis. FDA supplement guidance

When comparing products:

• Match the route. Oral MSM trial results do not validate an MSM cream. Bladder DMSO treatment does not validate a retail gel or roll-on.
• Read the actual ingredient amount. For an MSM blend, the total weight of the blend is not necessarily the MSM dose. Check the serving size and MSM amount per serving; if the label does not disclose it, you cannot match it to a trial dose.
• Do not convert an MSM gram dose into a DMSO percentage. A concentration is not a dosing equivalent.
• Separate purity from effectiveness. Ask for batch-specific identity and purity testing, but do not treat a purity claim as proof of clinical benefit.

Is MSM safer than DMSO?

The available evidence does not establish a dependable safety ranking. NCCIH lists digestive upset, skin irritation and garlic-like taste, breath or body odor for DMSO; for MSM, it lists allergic reactions, digestive upset and rashes. It also emphasizes uncertainty because safety research is limited. NCCIH safety summary

DMSO adds a concern that should not be transferred casually to MSM: it penetrates skin and can aid penetration of other medications. Its prescription label also warns that it may change the effects of concurrently administered medicines. That makes combining DMSO with topical drugs or homemade mixtures a separate safety question—not a way to reproduce an oral MSM trial. Research review; prescription precautions

For someone investigating an oral joint supplement, MSM is the relevant ingredient to evaluate, with possible but uncertain benefits. For someone offered prescription bladder DMSO, MSM is not a replacement. Discuss either product with a clinician before use, bringing the full label and medication list rather than just the abbreviation.