In multiple sclerosis (MS), the central nervous system, which includes the brain and spinal cord, becomes damaged. One type is called relapsing-remitting MS. With this type, you have flare-ups of the disease or relapses. Between these flare-ups, you have periods of recovery or remissions. One of these, the most common form, was relapsing-remitting MS (RRMS). Relapsing-remitting MS has defined as MS in which patients have relapses of MS and periods of stability in between relapses. Relapses are episodes of new or worsening symptoms not caused by fever or infection and that lasts more than 48 hours. Most people who seek treatment for MS go through relapses and remissions. Remission is a period in which you have no symptoms of the disease. A remission can last for weeks, months, or, in some cases, years.