Siponimod is primarily used in the treatment of relapsing forms of multiple sclerosis (MS), including clinically isolated syndrome, relapsing-remitting MS, and active secondary progressive MS. It works by modulating the immune system, specifically by binding to sphingosine-1-phosphate receptors on lymphocytes. This action prevents these immune cells from entering the central nervous system, thereby reducing inflammation and nerve damage. Siponimod is particularly beneficial for patients who have not responded well to other MS therapies or who are transitioning from relapsing-remitting to secondary progressive MS. It is administered orally, offering a convenient treatment option for patients. Regular monitoring of liver function and heart rate is recommended during treatment to manage potential side effects. Overall, siponimod helps slow disease progression and improves the quality of life for individuals with MS.