Recreational nitrous oxide use and its clinical implications

Nitrous oxide, a gas used in healthcare as an analgesic and anaesthetic and in the catering industry as a whipped cream aerosol propellant, has been misused since its discovery in the 18th century. It is commonly inhaled from balloons filled from 8 g whipped cream dispensers (‘whippets’), or more recently from larger 600 g to 2 g canisters. Acute complications include pneumothorax, hypoxia and frostbite from contact of the nitrous oxide canister with the skin or mucous membranes. Chronic use has the potential to cause nitrous oxide-induced neuropathy from sub-acute combined degeneration of the cord relating to functional vitamin B₁₂ deficiency; methylmalonic acid and homocysteine are biomarkers of nitrous oxide neuropathy. Other chronic effects include neuropsychiatric symptoms, anaemia, toxic leucoencephalopathy, rashes and an increased risk of thrombosis. Management of nitrous oxide neuropathy and other chronic complications consists of educating individuals on the importance of stopping nitrous oxide use, together with treatment with intramuscular vitamin B₁₂.