Nitrous oxide, also known as laughing gas, is a chemical with significant medical uses. Similarly to ketamine, it is used for its anaesthetic and pain-reducing effects. Both compounds are on the World Health Organisation’s List of Essential Medicines. When nitrous oxide gas is inhaled, it can lead to dissociative effects through its effect on gamma-aminobutyric acid type A and N-methyl-D-aspartate receptors in the brain. A small number of clinical trials have found favourable effects of nitrous oxide on scores of depression. A recent phase II study found that a 25% nitrous oxide mixture, versus a 50% mixture, had comparable therapeutic effects with fewer side effects.