Just 'nanging' around - harmful nitrous oxide use: a retrospective case series and review of Internet searches, social media posts and the coroner's database

Background The chronic recreational inhalation of nitrous oxide (N2O) 'nanging', can have adverse neurological and psychiatric effects. Aim To evaluate cases of chronic N2O use presenting to two hospitals, as well as to evaluate nationally N2O deaths reported to the coroner and trends in Internet searches and social media posts related to N2O. Methods Retrospective review of two toxicology units, from July 2017 to October 2020, of patients presenting with chronic N2O use and neurological and/or psychiatric symptoms. We evaluated 10 years (2010-2019) of Internet search and social media trends involving N2O and the National Coronial Information System (NCIS) database for deaths across Australia. Results Twenty-two patients were identified: median age 22 years, half female, 17 Asian background and 15 students. Presentations included decreased mobility or unsteady gait (n = 15) and psychiatric symptoms (n = 5). The median reported bulb use/day was 300 (interquartile range (IQR): 200-370), for a median of 6 months (IQR: 3-24). On magnetic resonance imaging, 10/18 had subacute combined degeneration of the spinal cord and 7/7 sensorimotor neuropathy on nerve conduction studies. All received high-dose intramuscular vitamin B-12 and 11 methionine. Despite prolonged rehabilitation, nine required walking aids on discharge. Since 2017, social media posts and Internet searches for N2O increased rapidly, the latter mostly directed at obtaining N2O canisters. From the NCIS, 36 deaths were identified, 12 unintentional (recreational drug use), 20 intentional self-harm and 4 traumatic. Conclusion We report a case series of symptomatic chronic N2O use, many with ongoing neurological sequelae. Furthermore, a sharp increase in Internet searches to obtain N2O cannisters was noted. Education of high-risk student groups on the long-term sequelae is important.

Automated summary

This study reports a series of cases with symptomatic chronic N2O use, many of whom experienced ongoing neurological sequelae. The study also found a sharp increase in internet searches for obtaining N2O canisters. Education about the long-term sequelae is important, particularly for high-risk student groups.