Buy Adderall XR Online Overnight from the best & reliable drugstore. Is Adderall XR same Adderall IR? Similarities- Both functions to treat ADHD and narcolepsy but in a different manner. Adderall XR and Adderall IR belong to the drug class known as stimulants. Both functions by affecting some natural chemicals in the brain that contribute to hyper activities. The generic edition of both variants is amphetamine and dextroamphetamine. Both may show side effects if not used in a directed manner. Dissimilarities- Adderall XR onsets its mechanism gradually over time, but Adderall IR works immediately after intake. XR's properties survive in the body for 12 hours, whereas Adderall IR survives for 6 hours after the last dosage. XR is not recommended to use on an as-needed basis, but IR is not safe effective in around-the-clock relief treatment.