Limited data suggest stable or declining NPS use among young people, with some exceptions.

• Time-series data on NPS use among young people are scarce and largely limited to high-income countries.
• Where data are available, the use of NPS is generally stable or declining, as corroborated by recent findings from the ESPAD (European School Survey Project on Alcohol and Other Drugs) study in Europe.
• Two exceptions to this trend are a medium-term increase in ketamine use in the United Kingdom until 2023 and an increase in NPS use (in particular of synthetic cannabinoids) in Italy between 2020 and 2022. However, in both countries, more recent data suggest these trends have stabilized or even reversed.