Relapses will occur to 90% of people with MS at some point. A relapse is usually defined as symptoms which are worsening over at least 24 hours, presumed to be due to MS, and not due to an infection which is causing a fever. Not all relapses require treatment. The first question is to ask whether one has such an infection prior to considering treatment of a relapse. If a bladder infection is suspected because of an increase in urgency to void, burning on urination, or odor of urine, this must be addressed by an appropriate physician. Milder relapses, such as tingling numbness, mild visual disturbances which do not disrupt reading or driving, or mild vertigo do not usually require treatment and will resolve often spontaneously. Relapses which will usually need treatment are those with significant bowel or bladder dysfunction, major difficulty with walking or balance, or vision loss. Sensation abnormalities which are very painful or involve difficulty using a limb may also benefit.
The usual treatments for relapses, often called exacerbations, of these illness requires very high doses of corticosteroids for a few days. These medications are not muscle-building steroids, but instead have a role in calming down the immune system. Small doses may be worse than no treatment at all, and the large doses are needed to get into the brain to interrupt the cycle of immune injury and get inflammatory cells out of the brain. Such treatments have been found to be very safe and rarely associated with any long term side effects.
Traditionally, these steroid treatments were administered by intravenous infusions. More recently, trials have demonstrated to be equally effective in large quantities given by mouth; however, most physicians are unfamiliar with this treatment, and it is usually prescribed only by specialized neurologists. While the action of the treatment is immediate, improvement usually continues for many weeks. These treatments work better the more recently the relapse has occurred. A physician will usually want to establish that you have a significant relapse and prescribe the appropriate treatment.
Other treatments are occasionally used in life-threatening or severe relapses unresponsive to treatment.