Daclizumab is used to prevent episodes of symptoms and slow the worsening of disability in people who have relapsing-remitting forms (course of disease where symptoms flare up from time to time) of multiple sclerosis (MS; a disease in which the nerves do not function properly and people may experience weakness, numbness, loss of muscle coordination, and problems with vision, speech, and bladder control). Daclizumab is usually used by people who were not helped by at least two other medications for MS. Daclizumab is in a class of medications called immunomodulators.