Laughing gas, or nitrous oxide, is used for pain relief. It is a small molecule, and when it gets into your bloodstream it travels to the brain and interferes with the transmission of chemical signals from one nerve cell to the next.
It has three main effects – pain relief, relaxation, and anaesthesia – and it’s the relaxation component that makes you laugh. It has been called ‘laughing gas’ for over 200 years, and it was originally used recreationally because of the pleasant effects it can have on the brain. However, it can have dangerous side-effects if used without medical supervision.