Methylphenidate is a stimulant that is the active ingredient in Ritalin and Concerta, two trademarked prescription drugs used to treat Attention Deficit Hyperactivity Disorder in children and teenagers. Methylphenidate is a stimulant chemically related to cocaine, but not it is as strong. It works by increasing certain brain chemicals, specifically norepinephrine and dopamine, which in turn increase feelings of well-being, self-confidence and pleasure. Although it makes most people feel hyper-energetic and nervous, this drug has the paradoxical effect of calming children who are hyperactive and have trouble concentrating. Because it is so widely prescribed to children, most people believe that methylphenidate is safe. However, the federal government classifies it under Schedule II Controlled Substances because it is addictive and has a potential for abuse. Cocaine and morphine are also Schedule II drugs.