Dimethyl Sulfoxide (DMSO) is a substance that, when applied to the skin, facilitates the absorption of medicinal compounds through the skin. While it has been valuable in arthritis treatments, its use in multiple sclerosis (MS) treatment has been based on one doctor's promotion. Without any controlled studies, this doctor, who wasn't even a neurologist and had no understanding of multiple sclerosis and its nature, treated several hundred patients with no success. DMSO is a perfect example of an MS treatment promoted for profit. It is clearly ineffective. Although it is not harmful, its application leaves the patient with a strong fishy odor.