Which class of controlled substances is considered most likely to be abused?

The class of controlled substances that is considered most likely to be abused is Schedule I. Schedule I substances are defined as drugs that have a high potential for abuse and are not accepted for medical use in the United States. This category includes substances like heroin and lysergic acid diethylamide (LSD), which are known for causing significant psychological or physical dependence.

While Schedule II substances, such as opioids and certain stimulants, also carry a high potential for abuse and can lead to severe psychological or physical dependence, they have accepted medical uses, which differentiates them from Schedule I substances. The strict regulation of these substances reflects the need to mitigate their abuse potential while allowing for their medicinal benefits.

Options in lower schedules, like Schedule III and Schedule IV, have progressively lower abuse potential and generally include medications that are considered less addictive or dangerous, which is why they are regarded as less likely to be abused compared to Schedule I and II drugs. Therefore, Schedule I substances are regarded as the most likely to be abused due to the absolute prohibition on their medical use and their association with strong addictive properties.