Ritalin (methylphenidate) is a central nervous system stimulant. It affects chemicals in the brain and nerves that contribute to hyperactivity and impulse control. Ritalin is used to treat attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD), and narcolepsy. Order Ritalin Now. eep the medication in a place where others cannot get to it. Read all patient information, medication guides, and instruction sheets provided to you.