Which schedule of controlled substances has a high potential for abuse and no accepted medical use?

Schedule I controlled substances are classified as having a high potential for abuse and no accepted medical use in the United States. This classification is reserved for substances that are deemed to have a significant risk of addiction and are not considered safe for use, even under medical supervision. Examples include drugs like heroin and lysergic acid diethylamide (LSD).

The absence of accepted medical use is a critical factor that distinguishes Schedule I substances from those in lower schedules. Substances in Schedule II, for instance, are recognized for potential medical applications, albeit with a high risk of abuse, such as opioids and stimulants. Meanwhile, Schedules III and IV include substances that lower in potential for abuse and are allowed for medical use under specific conditions. Thus, Schedule I stands alone as the category that reflects the highest risk and the absence of legitimate medical applications.