I am a psychopharmacologist and prescribe both Vyvanse and
Adderall, sometimes simultaneously. It is safe. They are ultimately both transformed
by the body to the same active metabolite, dextroamphetamine. They differ in the rate they are transformed, Adderall rapidly, Vyvanse slowly. For college students who sometimes study late at night, supplemental Adderall makes sense. Taking them together has an additive effect, not a synergistic effect.