From "Laughing Gas" to "Galaxy Gas": An Updated Review on the Neurological, Pathologic, and Psychiatric Sequelae of Nitrous Oxide Abuse.

Nitrous oxide (N₂O), a dissociative anesthetic and analgesic, has seen a concerning rise in recreational abuse, particularly among adolescents and young adults. This resurgence is fueled by its easy accessibility in large-volume, flavored canisters marketed as cooking aids, which exploit legal loopholes, as well as its promotion through popular culture and social media platforms like TikTok and YouTube. This literature review synthesizes current knowledge on N₂O abuse by systematically searching PubMed, Embase, Scopus, Web of Science, and PsycINFO for articles published from January 1, 2015, to February 3, 2025. The review focuses on the pathophysiology, symptoms, and long-term effects of N₂O abuse in both adult and pediatric populations, including its physical, psychiatric, and addiction-related consequences. The review of 13 studies, which included retrospective cohorts, case series, and cross-sectional surveys, highlights the severe neuropsychiatric and physical consequences of N₂O abuse. Epidemiological data consistently show that use is highest among young adults aged 16-30 years, with a notable overrepresentation of males and a disproportionate impact on socioeconomically disadvantaged populations. The most prominent physical effect is subacute combined degeneration of the spinal cord (SCD), which is a spinal cord disorder caused by demyelination of its lateral and posterior columns. It typically leads to neurological symptoms with common signs including numbness, tingling, muscle weakness, coordination problems, and difficulty walking. Biochemically, N₂O abuse leads to a functional vitamin B₁₂ deficiency, marked by elevated homocysteine and methylmalonic acid levels. Psychiatrically, N₂O use is strongly associated with a range of symptoms, including anxiety, depression, and psychosis. The review also notes patterns of compulsive use and polydrug abuse, which suggests a high potential for dependence. This review underscores the urgent need for heightened clinical suspicion of N2O abuse among healthcare professionals. Public health recommendations include enhanced regulation of N₂O sales, clearer product labeling, and targeted social media campaigns such as collaborating with popular content creators and public service announcements to combat misinformation about its safety. The "Galaxy Gas" trend, where individuals, particularly in schools and public spaces, purchase and misuse large N₂O canisters promoted on social media, warrants specific attention due to its broad reach and ease of access. Future research should prioritize on understanding the long-term neuropsychiatric impacts of N₂O and developing effective treatment strategies. Notably, recent progress has been made with health agencies enforcing age restrictions on the sale of high-volume N₂O canisters, including bans for those under 21.