MODEL RELEASED. Inhaling laughing gas from a balloon. Laughing gas is nitrous oxide, a gas used recreationally since the late eighteenth century. It produces euphoria, relaxation and hallucinations. It is used in medicine for anaesthesia and pain relief. Pressurised capsules of nitrous oxide (designed for the catering trade as a whipped cream propellant) are commonly used to fill balloons at clubs, festivals and parties. The gas is then inhaled from a balloon to give a brief "legal high". Repeated inhalation may cause oxygen deprivation.