Methylsulfonylmethane (MSM) is a chemical that occurs naturally in humans, as well as some green plants and animals.
According to the Food and Drug Administration (FDA), MSM is considered safe at dosages under 4,000 milligrams (mg) per kilogram (kg) per day and in energy bars at levels up to 30,000 mg/kg. MSM supplements are available in capsule or powder form. Taking more MSM than directed does not appear to provide better results.