Dexedrine is a brand name for dextroamphetamine, a medication used to treat attention deficit hyperactivity disorder (ADHD) and narcolepsy. The 5 mg dose is a lower strength, which may be prescribed for individuals who need a smaller amount to manage symptoms. It works by increasing the levels of certain neurotransmitters in the brain, helping to improve focus, attention, and impulse control. Typically taken once or twice a day.