MSM (methylsulfonylmethane) is a sulfur-containing compound related to DMSO. As a supplement it is used most often as an anti-inflammatory and for joint and muscle pain, including knee osteoarthritis.
Also known as: methylsulfonylmethane, dimethyl sulfone, organic sulfur.
In a 12-week knee osteoarthritis trial, people took 1.125 g three times a day (Debbi 2011). A 2017 review says MSM is well tolerated by most people at up to 4 g a day. These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. A 2017 review says MSM has Generally Recognized As Safe (GRAS) status; one of its authors lists an address at Bergstrom Nutrition, a supplement company.
What studies show: a 2008 systematic review found two MSM trials in knee osteoarthritis (52 people on MSM) that both reported less pain, and called the evidence positive but not definitive, with optimal dose and long-term safety unknown. In a 2011 trial of 49 people with knee osteoarthritis, MSM for 12 weeks improved pain and physical function scores, but the authors said the gains were small and may not matter clinically.
Safety: the 2017 review describes few known side effects, all mild, at up to 4 g a day. The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for MSM that applies to a supplement dose, so we do not list one.
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