Adderall is considered the first choice treatment option for ADHD(attention deficit hyperactivity disorder). Adderall has a half-life of 9 to 14 hours, which means that 9 to 14 hours after dosage, only half of the drug remains in your body. Adderall will usually completely clear your system within 72 hours (or 3 days). However, this can vary based on several factors. If you have an upcoming drug test, the pressure of passing it can feel overwhelming — especially if you have a history of substance use.