The majority of the pharmaceuticals that the FDA has approved for marketing in the United States are not on the CSA schedules, including most prescription drugs and all over-the-counter drugs. The NSDUH questionnaire includes some prescription psychotherapeutic drugs that are not on the CSA schedule, such as tramadol (Ultram®) and cyclobenzaprine (Flexeril®).
A chart that highlights commonly abused prescription drugs in the US
However, in 2003, approximately 15 million Americans reported using a prescription drug for nonmedical reasons at least once during the year.