Incidents with recreational nitrous oxide use before and after legislation: poisonings and police incidents in the Netherlands between 2020 and 2025

Objective In the Netherlands, a legislative amendment announced on December 9th 2019, banned the production, sale, purchase, and possession of nitrous oxide (N₂O) for recreational use, and became effective January 1st 2023. This study examined the impact of this policy change on the number of nitrous oxide-related health and police incidents. Methods We conducted a retrospective analysis of nitrous oxide-related incidents between 2020 and 2025 (up to September), including exposures reported to the Dutch Poisons Information Center and incidents recorded by the Netherlands Police. Interrupted time series analyses were conducted. Results In total, 431 exposures and 150,623 police incidents were identified. Exposures and incidents were highest in 2020 (N = 144 and N = 41,644) and declined in 2022 (N = 72 and N = 28,972, p ' 0.05), and, more pronounced, in 2023 (N = 23 and N = 9363, p ' 0.001). In 2024 and 2025 an increase was observed (p ' 0.001), although absolute numbers remained below pre-legislation levels (2024: N = 48 and N = 16,929). The median age of exposed patients was 23 years; 59% were male, 66% reported heavy use, and 39% exhibited signs of peripheral neuropathy. Most police incidents involved public disorder (70%), traffic offences (17%), and possession or trade (8%). Following criminalisation of possession or trade in 2023, police cases rose from N = 452 in 2022 to N = 3,798 (2% versus 22% of all N₂O-related incidents) in 2024. Conclusions Nitrous oxide-related incidents were declining prior to legislation in 2023 and decreased further in 2023. Although numbers rose again in 2024 and 2025, they remained below 2020-2022 levels. Ongoing monitoring is needed to evaluate long-term effects.