MSM, short for methylsulfonylmethane, is a naturally occurring sulfur compound sold widely as a dietary supplement. It’s most commonly taken for joint pain, inflammation, and skin health. You’ll find it in powder, capsule, and cream forms at virtually any supplement retailer, and it carries a “no questions” safety designation from the FDA for use as a food ingredient.
What MSM Actually Is
MSM is an organosulfur compound, meaning its key element is sulfur bound to organic (carbon-containing) molecules. It goes by several other names: dimethyl sulfone, methyl sulfone, and sometimes just “organic sulfur.” It’s a white, crystalline powder that dissolves easily in water.
In nature, MSM is part of the Earth’s sulfur cycle. Its production starts in the ocean, where algae, phytoplankton, and other marine microorganisms produce a precursor compound. That compound eventually converts to MSM and enters the atmosphere, then returns to land through rain. From there it ends up in soil and, ultimately, in the food supply. You consume small amounts of MSM through fruits, vegetables, grains, cow’s milk, coffee, tea, and even beer and port wine.
Sulfur plays a role in building connective tissue throughout the body. It’s involved in producing collagen, hyaluronic acid, and keratin, the structural proteins that form cartilage, skin, hair, and nails. MSM’s main appeal as a supplement is that it provides a bioavailable source of this sulfur.
How MSM Works in the Body
MSM’s most studied mechanism is its effect on inflammation. In lab studies, it blocks a key inflammatory signaling pathway called NF-kB. When this pathway is overactive, your immune cells pump out inflammatory molecules that cause pain and swelling. MSM appears to keep this pathway in check, reducing the production of several pro-inflammatory signals, including two of the most well-known ones: interleukin-6 and tumor necrosis factor-alpha. It also lowers levels of nitric oxide and prostaglandin E2, both of which drive inflammation and pain at the tissue level.
These are cell-study findings, so they don’t translate directly to what happens when you swallow a capsule. But they offer a plausible explanation for the effects seen in human trials, particularly around joint pain and skin health.
MSM for Joint Pain and Osteoarthritis
Joint pain, especially from osteoarthritis, is the most popular reason people take MSM. A pilot clinical trial tested 6 grams per day (split into two 3-gram doses) against a placebo in 50 adults aged 40 to 76 with knee osteoarthritis. After 12 weeks, the MSM group showed significant improvements in pain scores and physical function compared to placebo. They also reported better ability to perform daily activities. Stiffness scores didn’t change significantly.
The improvements were meaningful but modest, and the study was small. MSM is not a replacement for other osteoarthritis management strategies, but many people use it alongside them as a complementary approach.
Effects on Skin, Hair, and Nails
MSM has gained traction in the beauty supplement space, and there’s some clinical backing for the skin claims. A placebo-controlled study found that 3 grams per day of oral MSM significantly reduced facial wrinkles and skin roughness. Skin firmness, elasticity, and hydration all improved as well. The hydration benefits appeared within four weeks and continued improving through eight weeks before leveling off. Interestingly, a lower dose of 1 gram per day also improved hydration, just more slowly, reaching its plateau around 12 weeks.
The connection to hair and nails is more theoretical. MSM contributes sulfur needed for keratin synthesis, the protein that makes up hair and nails, but clinical studies haven’t directly measured whether supplementation leads to stronger or faster-growing hair and nails.
MSM and Exercise Recovery
A double-blind trial gave runners 3 grams of MSM daily for 21 days before a half-marathon and two days after. The supplement did not reduce standard blood markers of muscle damage. However, it did lower post-race muscle and joint pain by clinically meaningful amounts. Muscle pain dropped by nearly 20 mm on a 100 mm pain scale compared to placebo, and joint pain was 9 to 10 mm lower. These reductions didn’t reach statistical significance in the small 22-person study, but they crossed the threshold that pain researchers consider clinically relevant, meaning the difference is large enough for a person to actually feel it.
Typical Dosage
Most clinical trials use between 1 and 6 grams per day. The 6-gram-per-day dose (split into 3 grams twice daily) is the most common in osteoarthritis research. Skin studies have used 1 to 3 grams daily. The FDA’s “no questions” letter covers MSM as a food ingredient at concentrations up to 4,000 milligrams per kilogram in beverages and up to 30,000 milligrams per kilogram in food bars like granola and energy bars.
MSM is usually taken with food, though it’s water-soluble and absorbs well regardless. Many supplement formulas combine it with glucosamine or chondroitin for joint support.
Safety and Side Effects
MSM has a strong safety profile at typical supplement doses. Clinical trials consistently report no significant adverse effects when it’s taken on its own. The FDA granted it GRAS (Generally Recognized as Safe) status in 2008, and it’s widely used as both a supplement and a food ingredient.
One area worth noting involves combination products. MSM is frequently sold alongside glucosamine and chondroitin. While MSM itself showed no significant inhibition of the liver enzymes responsible for drug metabolism, glucosamine and chondroitin have been linked to elevated blood-thinning effects when taken with warfarin and similar anticoagulant medications. If you take a combination joint supplement that includes glucosamine or chondroitin alongside a blood thinner, that interaction is worth discussing with your pharmacist. The MSM component itself does not appear to be the concern.
Common mild side effects that some users report include bloating, nausea, and digestive discomfort, particularly at higher doses or when starting supplementation for the first time. These typically resolve within a few days.