Background: Nitrous oxide (N2O) is used worldwide for analgesia and anesthesia. It is also used for recreational purposes by some people. N2O can have major side effects (myeloneuropathy, delusions, emphysema) when used to excess. In France, N2O is available as an equimolar mixture of oxygen and nitrous oxide (EMONO). Its substance use disorder potential is monitored by the French Monitoring Centre for Addiction (CEIP-A) network. Our objective is to provide an overview of the substance use disorder potential of N2O in general, and of EMONO in particular. Methods: This paper is based on a systematic review of the literature for case reports involving N2O use disorder and on CEIP-A network cases involving EMONO use disorder. We characterized use disorder in accordance with DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) criteria. Furthermore, we considered data relating to medical history, age, gender, and N2O consumption habits. Results: We identified 59 cases of N2O use disorder in the literature and 17 cases of EMONO use disorder from the CEIP-A network. More than 90% of the cases used N2O in larger quantities and for longer than intended. Conversely, more negative as opposed to positive cases have been documented regarding tolerance and failed attempts to reduce usage. Conclusions: A specific profile of substance use disorder starts to emerge from all the cases studied here. Furthermore, we identified another way N2O use disorder can appear: through exposure for medical purposes.
Keywords: Abuse; EMONO; assessment; dependence; nitrous oxide; substance use disorder.