A new psychoactive substance (NPS) can be described as a new narcotic or psychotropic drug, in pure form or in preparation, that is not controlled by the United Nations drug conventions, but which may pose a public health threat comparable to that posed by substances listed in these conventions. Health harms associated with NPS range from seizures to agitation, aggression, intoxication, acute psychosis as well as dependence.

In order to rapidly detect and assess threats posed by NPS, the European Union Early Warning System (EWS), was established by the European Union Drugs Agency (EUDA) in 1997. The system is composed of a multisectoral, multidisciplinary, and multiagency network, which includes the EUDA, 29 national early warning systems (27 European Union Member States, Turkey, and Norway), Europol and its law enforcement networks, the European Medicines Agency, and the European Commission.