I tried this many years ago, and took it regularly for years. Haven't tried it again since getting tinnitus however. What I recall from all those years ago is that MSM can greatly increase cell wall permeability. When I first tried it, I became quite nauseous for several hours.
Apparently when you increase cell permeability, various toxins that may be trapped inside the cell are able to move into the bloodstream. If too much is released at a time, the body can become toxic until it's able to be eliminated. I can see where improved cell wall permeability could be a factor in severity of tinnitus.
My understanding is that the sulfur in MSN (Methyl
sulfonylmethane) is what creates most of the positive effects from supplementing with it. Some people get the same sulfur injection by supplementing with DMSO (dimethyl
sulfoxide), which appears to have the potential for improving tinnitus as well. --
Dimethyl sulfoxide [DMSO] therapy in subjective tinnitus of unknown origin.