Adderall is a prescription drug used to treat ADHD, narcolepsy and obesity. It's also illegally used for non-medical purposes to improve focus and decrease fatigue. The drug is a stimulant that increases dopamine levels in the brain in order to promote wakefulness and attention span. ​Adderall works by blocking the reabsorption of dopamine by neurons (neuron cells), which allows more time for dopamine to be released into synapses (the spaces between neurons).