Prescription stimulants are often used to treat disorders such as attention deficit hyperactivity disorder (ADHD). Drugs like amphetamine-dextroamphetamine (Adderall) and methylphenidate (Ritalin) help people with ADHD feel calmer and more focused. They can also be used to narcolepsy.But these drugs can also be abused. When they are used improperly, stimulants can harm a person's health.These drugs are easy to come by, too. Teenagers can often get them from classmates or friends with prescriptions. In fact, among high school seniors, amphetamines are the third most commonly used illicit drug.