INTRODUCTION: As management of multiple sclerosis (MS) requires life-long treatment with disease-modifying agents, any risks associated with long-term use should be considered when evaluating therapeutic options.AREAS COVERED: Immune cells of the innate and adaptive immune systems play various roles in the pathogenesis of MS. MS therapies affect the immune system, each with a unique mode of action, and consequently possess different long-term safety profiles. Rare, but serious safety concerns, including an increased risk of infection and cancer, have been associated with immunosuppressant use. The risks associated with newer immunosuppressive agents, which target specific elements of MS disease pathophysiology, are not yet fully established as the duration of clinical trials is relatively short and post-marketing experience is limited. Non-immunosuppressants used to treat MS have well-defined safety profiles established over a large number of patient-years demonstrating them to be well-tolerated long-term treatment options. When considering the long-term use of disease-modifying agents for treating MS, classification as immunosuppressants or non-immunosuppressants can be useful when evaluating potential risks associated with chronic use.EXPERT OPINION: A successful therapeutic strategy for any serious, chronic disease such as MS should weigh effectiveness versus long-term safety of available treatments.