February 28, 2009. According to HomeDrugTestingKit, amphetamines are detectable in urine for up to 4 days. This is an average as everyone metabolizes medication at different rates. According to the prescribing packet insert for Adderall, it has a half-life of 12 hours for staying in your system. For more information about how it affects your bloodstream I suggest you refer to the packet insert with the medication, or ask your doctor. It's important to review the precautions and side effects of Adderall before using. If misused, this medication could result in serious heart and blood pressure problems.