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MSM Safety

MSM is safe with no reported adverse effects, even at very large dosages.

Is MSM Safe?

Published scientific studies have shown MSM to be safe for human and animal use. Even at large dosage levels, there are no known significant adverse effects or drug interactions. Notably, these studies were conducted on highly purified forms of MSM; consumers should determine if the MSM they use has been appropriately processed to remove microscopic toxins or impurities. Read more in MSM Manufacturing.

Some manufacturers are taking extra steps to ensure product safety. Read more.

MSM and Allergies - MSM Side Effects

There have been no reported cases of allergic reactions to MSM in the medical literature, though there are a handful of unpublished anecdotes of minor side effects like loose stools, stomach upset or skin rashes, conditions which disappeared immediately after stopping the supplementation. For more on allergies & side effects, see the Consumer FAQ.

Dr. Stanley Jacob M.D. of the Oregon Health & Science University reports treating over 18,000 patients in his medical practice, some of whom where given very high dosages, without adverse effects.

The toxicology of MSM has been explored in several studies:


Horváth K, Noker PE, Somfai-Relle S, et al. Toxicity of methylsulfonylmethane in rats. Food Chem Toxicol 2002; 40:1459-62.


Goldstein P, Magnano L, Rojo J. Effects of dimethyl sulfone (DMSO2) on early gametogenesis in Caenorhabditis elegans: ultrastructural aberrations and loss of synaptonemal complexes from pachytene nuclei. Reprod Toxicol 1992; 6:149–59.
Concern has been raised based on the results of this in vitro study, which found meiosis was interrupted in early gametogenesis in the nematode Caenorhabditis elegans (C. elegans is a small (about 1 millimeter), primitive worm that shares certain essential biological characteristics with humans (e.g., it produces sperm and eggs, reproduces, has a nervous system, etc.). Its short lifespan, rapid development, and easy cultivation under controlled conditions make it a favorite of research scientists as a model for toxicologic assays.) when it was grown in concentrations of MSM exceeding 1%. Increasing concentrations of MSM impaired the fecundity and viability of treated worms. This study is actually attempting to suggest the possibility of a teratogenic effect. However, more definitive research has shown no teratogenic effects or developmental toxicity.


Lin A, Nguy CH, Shic F, Ross BD. Accumulation of methylsulfonylmethane in the human brain: identification by multinuclear magnetic resonance spectroscopy. Toxicol Lett 2001; 123:169–77.
In vivo magnetic resonance spectroscopy (MRS) was used to detect and quantify MSM in the brains of four patients with memory loss and in three normal volunteers all of who had ingested MSM at the recommended doses of 1-3 g daily. MSM was detected in all subjects at concentrations of 0.42-3.40 mmole/kg brain and was equally distributed between gray and white matter. MSM was undetectable in drug-naive normal subjects (N=25), patients screened for 'toxic exposure' (N=50) or patients examined with 1H MRS for the diagnosis of probable Alzheimer Disease (N=520) between 1991 and 2001. No adverse clinical or neurochemical effects were observed. Appearance of MSM in significant concentrations in the human brain indicates ready transfer across the intact blood-brain barrier.


Hixson O.  Acute intragastric toxicity (LD-50). Dimethyl sulfone (methylsulfonylmethane, MSM). Laboratory of Vitamin Technology, Inc., Chicago, Illinois, August 21, 1958.
Study to assess acute intragastric toxicity of MSM. LD50 could not be established because even the maximum dose of 20g/kg failed to kill any of the animals (n = 10); no adverse effects were noted (the maximum recommended dose in humans approximates 300mg/kg).


MSM Toxicity in rats: The first and only toxicology study of MSM to be published in a peer-reviewed journal. Published in the Journal of Food & Chemical Toxicology. GLP-compliant. No adverse effects were noted in either acute or subchronic (90) studies at dose levels of 2 g/kg in the acute phase and 1.5 g/kg in the subchronic phase. Toxicology, lab, gross pathology, histology were all negative.


Rose SE, Chalk JB, Galloway GJ, Doddrell DM. Detection of dimethyl sulfone in the human brain by in vivo proton magnetic resonance spectroscopy. Magn Reson Imaging 2000; 18:95–8.


Schoenig G. Acute oral toxicity of sample No. 751, dimethyl sulfone 1 BT No. A6409. Industrial BIO-TEST Laboratories, Inc., Northbrook, Illinois, September 19, 1968.