Novel psychoactive substance

Novel psychoactive substance (NPS) is a regulatory category covering any compound that produces psychoactive effects but is not listed in the main UN drug-control treaties: the 1961 Single Convention on Narcotic Drugs, the 1971 Convention on Psychotropic Substances, and the 1988 Convention Against Illicit Traffic. The compounds in this category often mimic the effects of scheduled drugs while falling outside their formal coverage.

The label is a monitoring and legislative tool, not a pharmacological class. It was adopted and standardised by international agencies including the United Nations Office on Drugs and Crime (UNODC) and the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA, now EUDA). "Novel" does not require that a compound be newly synthesised — substances first described decades ago enter this category when they begin circulating commercially. The label "new psychoactive substance" appears interchangeably in many official texts.

What it means in practice

Because NPS fall outside the UN schedules, they initially occupy a legal gap — technically uncontrolled until a national or treaty authority acts. Jurisdictions close that gap in two main ways.

The first is compound-by-compound control: adding each substance to a national controlled-drugs list, often through emergency or temporary scheduling powers that allow rapid placement without full legislative review. The second is a blanket or analogue-based approach: prohibiting any psychoactive substance not on an exemption list, or treating compounds structurally similar to a named controlled drug as falling under its schedule.

The analogue route carries uncertainty. Whether a compound meets the statutory similarity threshold is regularly a question for courts, not administrative classification, and outcomes can vary.

How jurisdictions vary

The United Kingdom's Psychoactive Substances Act 2016 takes a blanket approach: supply of any substance capable of producing a psychoactive effect is prohibited, with named exemptions for alcohol, tobacco, caffeine, and medicinal products. This removes the traditional lag between a substance appearing commercially and a control order being made.

In the United States, the Federal Analogue Act — a provision of the Controlled Substances Act — allows prosecution of compounds substantially similar in chemical structure or pharmacological effect to a Schedule I or II substance, with similarity established in court. Emergency scheduling powers have also been used to place specific synthetic classes onto Schedule I on a temporary basis.

Within the European Union, an Early Warning System coordinated through EUDA lets member states share data on newly identified compounds; national legislative responses then differ substantially. The same compound can be prohibited in one country, subject to a blanket measure in a second, and unregulated in a third.

What is contested

The NPS category is defined by regulatory status, not by pharmacological profile or documented harm. A compound with an established safety record is classified identically to one on which almost no published data exists.

Monitoring bodies including UNODC have noted that some NPS have carried acute toxicity profiles more severe than those of the scheduled substances they were designed to replace, yet carried no controlled status at the time they emerged. Being outside the UN schedules says nothing about a compound's risk.

Scope and currency

This entry is not legal advice and does not describe the law in any particular jurisdiction. Whether a specific compound is controlled, and under what conditions, depends on jurisdiction, statute, and date. The position stated here reflects information available as of August 2026.

For any substance covered on these pages, the per-substance legal status section carries jurisdiction-specific information with a source and its own date — that section is the appropriate value to rely on rather than this general overview.