Adderall is a widely prescribed central nervous system (CNS) stimulant medication that contains a combination of two stimulant drugs: amphetamine and dextroamphetamine. These are synthetic substances that work by altering natural chemicals in the brain to improve focus, attention, and impulse control. Adderall is most commonly used to treat Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy, a neurological sleep disorder.