Diagnosis and management of toxicity associated with the recreational use of nitrous oxide

CMAJ | August 21, 2023 | Volume 195 | Issue 32 E1075 Nitrous oxide (N2O) has become a popular but dangerous recreational drug. Colloquially referred to as “laughing gas,” it was first used therapeutically in 1844 for patients undergoing dental surgery.1 Although a weak anesthetic, it remains in use today, especially for pediatric and dental procedures.2 Its recreational use is now recognized as a growing problem in many jurisdictions, including Australia3–5 and several European countries,6 particularly the United Kingdom.7 The true prevalence of recreational nitrous oxide use in Canada is unknown. However, 10% of all respondents and 15% of Canadian respondents to the 2021 Global Drug Survey reported having used nitrous oxide in the preceding year.8 This Internet-based survey provides insight about patterns of drug use, but respondents are not representative of the general population. Although no Canadian agencies track nitrous oxide use, evidence of substantial recreational use is apparent in Toronto and Montréal.9,10 Large quantities of nitrous oxide and associated paraphernalia are easily ordered online, with rapid shipping to major cities.11 The drug’s popularity relates in part to its low cost, ease of access and perception of safety relative to other drugs.12,13 Although acute, heavy use of nitrous oxide can occasionally cause death by asphyxiation,14,15 isolated, short-term use rarely leads to serious complications.16 Regular inhalation, however, can have serious and even devastating neurologic consequences. We discuss recreational nitrous oxide use and its toxicity, including methods and patterns of use, patho physiology, clinical presentation, diagnosis and management. We draw on evidence from case reports, case series, surveys and mechanistic studies related to nitrous oxide use and its complications (Box 1).