DMSO (dimethylsulfoxide) is an industrial solvent that is a byproduct of the paper industry. It was originally used as a pain killer for animals, for strained muscles in horses for example. I remember my grandfather having a bottle of it for this reason. He was born and raised on the ranch.
Anyway, I have never used it. I have heard of people experiencing a burning effect when applying it and it will instantly make you smell like garlic. If people are going to use it they need to be EXTREMELY careful. This solvent travels through the skin at such a rapid rate that it will carry anything on the skin with it. This includes lotions, insecticides, insect repellents, dirt, soap scum etc. So the application area must first be cleaned well with soap and water, then cleaned again with rubbing alcohol to remove the soap scum. It is best applied with roll-ons that it is also sold in. This way it will not absorb through the fingers, which may not be as clean, and it will not eat the gloves if you wear them to prevent the DMSO from being absorbed through the fingers.
Some people have also recommended using with oxidizers such as MMS or peroxide. I think this is a really dangerous idea. I posted this on another board about this exact thing:
You need to be careful with mixing chemicals. Remember the Ramirez case? The lady was using DMSO, which researchers believe was oxidized in the the powerful toxin DMSO4 (dimethylsulfate), which ended up hospitalizing a lot of people. Point is that the chemical reaction between DMSO and MMS, an oxidizer, is unknown. And there is at least one case where it looks like the oxidation of DMSO has lead to the formation of a poison in a human. Here is a link to the story:
A lot of people also don't realize that commercial MSM (methylsulfonylmethane)is actually a synthetic as well. Promoters claim that it is all natural, but this is not true. MSM is found in nature as a natural product. But only in trace amounts. Commercial MSM is produced by the heating of DMSO, which adds an oxygen atom creating DMSO2, otherwise known as MSM.
Over all DMSO is great for pain and swelling, but due to the instant garlicky smell and the hassles of trying to use it safely I will pass myself.