Are all drugs judged equally? What is drug scheduling in the US and how do Schedule I, II, III, IV and V differ?

The administration of Donald Trump has initiated a significant change in federal drug policy by reclassifying state-licensed medical marijuana as a less dangerous substance. The order, signed by acting Attorney General Todd Blanche, will move cannabis from Schedule I, which is reserved for drugs with high abuse potential and no accepted medical use, to the less restrictive Schedule III category. While the decision does not legalise marijuana at the federal level, it alters its regulatory treatment, offering tax relief to licensed operators and easing restrictions on research. The move marks a notable step in aligning federal policy with expanding state-level cannabis laws.

Drug scheduling in the United States refers to the classification of controlled substances under the Controlled Substances Act of 1970. Administered by the Drug Enforcement Administration, the system groups drugs into five categories based on medical use, potential for abuse and likelihood of dependence. As the agency notes, “drugs, substances, and certain chemicals… are classified into five distinct categories” depending on these factors.

The framework was introduced to regulate the manufacture, distribution and use of potentially harmful substances. It ensures that prescribers and dispensers operate under strict licensing. The central principle is proportional control: as abuse potential decreases from Schedule I to Schedule V, regulatory restrictions also ease.

Schedule I substances are defined as having “no currently accepted medical use and a high potential for abuse”. These drugs cannot be prescribed under federal law. Examples include heroin, LSD and marijuana in its non-approved forms. The order marks a first step towards broader federal acceptance, with the Justice Department set to hold a June 29 hearing on reclassifying marijuana to Schedule III. Even substances not explicitly listed may be treated as Schedule I if they are chemically similar to existing drugs.

Schedule II drugs retain a high abuse potential but are recognised for medical use. These include fentanyl, oxycodone, cocaine and methamphetamine. Their use may lead to ‘severe psychological or physical dependence’, and they are subject to strict controls, including limits on refills.

Schedule III substances fall between high-risk and low-risk categories. They have a 'moderate to low potential for physical and psychological dependence', according to DEA. Examples include products containing limited quantities of codeine, ketamine and anabolic steroids such as testosterone. Their regulatory treatment is less stringent than Schedule I or II drugs.

Schedule IV drugs are considered to have a low risk of abuse and dependence relative to higher schedules. Common examples include diazepam, alprazolam and tramadol. These medications are widely prescribed but remain controlled to prevent misuse.

Schedule V substances have the lowest potential for abuse among controlled drugs and contain limited quantities of certain narcotics. They are commonly used for antidiarrhoeal, cough-suppressing and pain-relief purposes. Examples include low-dose codeine cough syrups such as Robitussin AC, as well as Lomotil, Motofen, Lyrica and Parepectolin.