<p dir="ltr">Back <i>et al</i>. have addressed increased concern about nitrous oxide (N<sub>2</sub>O) use by evaluating the available peer-reviewed evidence against the DSM-5 substance use disorder criteria. The study is important, because media reports of recreational N<sub>2</sub>O use and related harms have exploded around the world. While there is no reliable evidence regarding the prevalence of N<sub>2</sub>O use, public and political concern has led to its re-classification as a class C drug in the United Kingdom, meaning that people caught with it can be charged by police, given a warning, fined or even jailed. Similarly, in January 2023, the Netherlands banned the sale and possession of N<sub>2</sub>O after 1800 road accidents, including 63 fatal crashes, were linked to the drug in a 3-year period.</p>