Multiple sclerosis (MS) is an autoimmune disorder of the central nervous system that results in inflammation, demyelination, and axonal and neuronal loss. The typical course of MS is one of symptom exacerbations followed by periods of remission; however, patients will eventually accrue disability from the exacerbations. Several drugs, including interferon beta, glatiramer acetate, natalizumab, and fingolimod, are effective in lowering relapse rates and slowing the progression of MS. For patients with suboptimal response to medication, switching to another first- or second-line medication can be an effective strategy.