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.