Nitrous oxide (N2O), a long-standing anesthetic, is known for its recreational use, and its consumption is on the rise. Several case studies have reported neurological and psychiatric complications of N2O use. To date, however, there has not been a study using standardized diagnostic procedures to assess psychiatric comorbidities in a patient consuming N2O. Here, we report about a 35-year-old male with magnetic resonance imaging confirmed subacute myelopathy induced by N2O consumption, who suffered from comorbid cannabinoid and nicotine dependence as well as abuse of amphetamines, cocaine, lysergic acid diethylamide, and ketamine. Additionally, there was evidence of a preceding transient psychotic and depressive episode induced by synthetic cannabinoid abuse. In summary, this case raises awareness of an important mechanism of neural toxicity, with which physicians working in the field of substance-related disorders should be familiar. In fact, excluding N2O toxicity in patients with recognized substance-related disorders and new neurological deficits is compulsory, as untreated for months the damage to the nervous system is at risk of becoming irreversible.