Adderall is a prescription medication composed of two stimulant drugs: amphetamine and dextroamphetamine. These active ingredients work as central nervous system (CNS) stimulants, affecting chemicals in the brain and nerves that contribute to hyperactivity and impulse control. Adderall is most commonly prescribed for treating Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy, a sleep disorder that causes excessive daytime sleepiness and sudden attacks of sleep.