Disadvantages to the use of DMSO-d6 are its high viscosity, which broadens signals, and its hygroscopicity, which leads to an overwhelming H2O resonance in the 1H-NMR spectrum. It is often mixed with CDCl3 or CD2Cl2 for lower viscosity and melting points. DMSO is also used to dissolve test compounds in in vitro drug discovery and drug design screening programs, including high-throughput screening programs. This is because it is able to dissolve both polar and nonpolar compounds, can be used to maintain stock solutions of test compounds (important when working with a large chemical library), is readily miscible with water and cell culture media, and has a high boiling point (this improves the accuracy of test compound concentrations by reducing room temperature evaporation). One limitation with DMSO is that it can affect cell line growth and viability, with low DMSO concentrations sometimes stimulating cell growth, and high DMSO concentrations sometimes inhibiting or killing cells.DMSO is used as a vehicle in in vivo studies of test compounds too. It has, for example, been employed as a co-solvent to assist absorption of the flavonol glycoside Icariin in the nematode worm Caenorhabditis elegans. As with its use in in vitro studies, DMSO has some limitations in animal models. Pleiotropic effects can occur and, if DMSO control groups are not carefully planned, then solvent effects can falsely be attributed to the prospective drug.
In 1978, the US FDA approved DMSO for treating interstitial cystitis. In 1980, the US Congress held hearings on claims that the FDA was slow in approving DMSO for other medical uses. In 2007, the US FDA granted "fast track" designation on clinical studies of DMSOs use in reducing brain tissue swelling following traumatic brain injury. DMSO exposure to developing mouse brains can produce brain degeneration. This neurotoxicity could be detected at doses as low as 0.3 mL/kg, a level exceeded in children exposed to DMSO during bone marrow transplant.DMSO disposed into sewers can also cause odor problems in municipal effluents: waste water bacteria transform DMSO under hypoxic (anoxic) conditions into dimethyl sulfide (DMS) that has a strong disagreeable odor, similar to rotten cabbage. However, chemically pure DMSO is odorless because of the lack of C-S-C (sulfide) and C-S-H (mercaptan) linkages. Deodorization of DMSO is achieved by removing the odorous impurities it contains. Explosion hazard
Dimethyl sulfoxide can produce an explosive reaction when exposed to acyl chlorides; at a low temperature, this reaction produces the oxidant for Swern oxidation. DMSO can decompose at the boiling temperature of 189 °C at normal pressure, possibly leading to an explosion. The decomposition is catalyzed by acids and bases and therefore can be relevant at even lower temperatures. A strong to explosive reaction also takes place in combination with halogen compounds, metal nitrides, metal perchlorates, sodium hydride, periodic acid and fluorinating agents.