Adderall XR 15 mg is a combination medicine of two drugs are dextroamphetamine and amphetamine. Adderall works on stimulants of the central nervous system. The 15 mg pills of Adderall is a common dose. This medicine is an extended-release medicine. Commonly doctors start treatment with a low dose such as 5 mg, 10 mg if it is helpful for the patient then the doctor continues the treatment and increases the dose.