MSM (methylsulfonylmethane) is an organic sulfur compound used primarily for joint pain, seasonal allergies, and inflammation. It occurs naturally in small amounts in fruits, vegetables, and grains, but the quantities people take as supplements far exceed what food provides. The evidence behind MSM is mixed depending on the benefit you’re looking at. Some uses have solid clinical trial data, while others rely mostly on animal studies or lab research.
Allergy and Sinus Relief
Seasonal allergies may be the best-supported use for MSM. A randomized, double-blind trial found that taking 3 grams of MSM daily for 14 days reduced all major nasal allergy symptoms after participants were exposed to a standard allergen. Nasal obstruction dropped by about 50%, runny nose decreased by 56%, and sneezing fell by 64%. Participants also showed a 17% improvement in nasal airflow, meaning they could actually breathe better through their nose, not just feel like they could.
Even lower doses had measurable effects. Just 1 gram daily reduced nasal obstruction by 42% and runny nose symptoms by 67% over the same two-week period. A single large dose of 12 grams produced rapid but less comprehensive relief, cutting itchy nose symptoms by 67% and watery eyes by 53%, though it didn’t improve nasal airflow the way smaller daily doses did. The sweet spot appears to be 3 grams per day, which was the only dose that significantly reduced every symptom category measured, including sneezing.
Anti-Inflammatory Properties
MSM targets a specific part of the body’s inflammatory machinery. Lab research shows it selectively blocks a protein complex called the NLRP3 inflammasome, which acts as an alarm system in immune cells. When this complex overactivates, it drives chronic inflammation linked to joint pain, metabolic disorders, and tissue damage. MSM dials down the production of several inflammatory signaling molecules, including ones responsible for pain, swelling, and redness at injury sites.
MSM also reduces the production of damaging molecules called reactive oxygen species inside the energy-producing parts of cells. This dual action, lowering both inflammatory signals and oxidative stress at the cellular level, is likely why people report improvements in joint comfort. The compound has long been marketed alongside glucosamine and chondroitin for arthritis, and its pain-relieving properties appear to be genuine, though the magnitude of relief varies between individuals.
Skin Protection
Animal research suggests MSM can protect skin from sun-related damage. In a study using hairless mice exposed to UV radiation, MSM supplementation preserved the elastic fibers in the skin significantly better than no treatment. Elastic fiber structure, which determines how firm and resilient your skin feels, scored 0.82 out of 1.0 in the MSM-treated group compared to 0.55 in the UV-exposed group that received no MSM. Wrinkle scores were also 40% lower in treated animals, and skin thickening from UV damage was reduced.
These results are promising but come with an important caveat: they’re from mice, not people. No large human clinical trials have measured wrinkle depth or skin elasticity changes from oral MSM supplementation. The biological rationale is sound since sulfur is a building block for collagen and keratin, the proteins that give skin its structure. But the leap from mouse skin studies to visible anti-aging effects in humans hasn’t been confirmed yet.
Exercise Recovery
Despite its popularity among athletes, MSM doesn’t appear to reduce muscle damage from intense exercise. A double-blind, placebo-controlled trial involving half-marathon runners found that MSM supplementation had essentially no effect on two key markers of muscle breakdown. Blood levels of these markers rose sharply after the race in both the MSM and placebo groups, with no meaningful difference between them at any time point: race day, one day after, or two days after.
This doesn’t mean MSM is useless for active people. Its anti-inflammatory effects could still help with joint comfort during exercise, particularly for people with existing joint issues. But if you’re taking MSM specifically to recover faster from hard workouts or reduce muscle soreness, the evidence doesn’t support that expectation.
Hair and Nail Growth
MSM is widely promoted for stronger hair and nails, but human evidence is thin. The most controlled study available used Ragdoll kittens, not people, and found no significant differences in hair length or hair diameter between MSM-supplemented and control groups over 65 days. Some changes in hair texture and scale structure were observed, but they were inconsistent across dosage groups and time points.
The theoretical basis is that sulfur from MSM supports keratin production, the protein that makes up hair and nails. Many people report subjective improvements, and sulfur is genuinely important for keratin structure. But objective measurement data showing MSM makes human hair grow faster or nails grow harder simply doesn’t exist in published research yet.
Safety and Dosage
MSM has a strong safety profile. The FDA reviewed it and had “no questions” about its use as a food ingredient at levels up to 4,000 milligrams per kilogram in beverages and supplements. Clinical trials have generally found it safe at typical supplemental doses, with no significant adverse effects reported as monotherapy.
Most clinical trials use doses between 1 and 6 grams per day, with 3 grams daily showing the best results for allergy relief. Lab testing found that MSM does not inhibit any of the seven major liver enzymes responsible for processing medications, which means it has a low likelihood of interfering with drugs you might already be taking. That said, if you take blood-thinning medications, it’s worth noting that some related joint supplements (glucosamine and chondroitin, often sold alongside MSM) have had reported interactions with anticoagulants, so the combination products deserve more caution than MSM alone.
Common side effects, when they occur, tend to be mild digestive complaints. MSM is chemically related to DMSO, a solvent that causes skin irritation and a strong odor, but MSM itself doesn’t share those problems. It’s a much more stable compound that delivers similar sulfur without the unpleasant side effects of its chemical cousin.