Nitrous oxide, better known as laughing gas, is often used in dental surgeries to kill the pain. But when people start to inhale it for recreational purposes, it can cause serious heath problems.

The Shanghai Mental Health Center recently admitted a 19-year-old patient with a rare addiction to laughing gas, the second such case this year. The patient once took a couple of gas canisters at a party while he was studying in the US, but later it turned into an addiction, and worsened to the point when he inhaled 1,000 canisters in a single day. Small canisters are sold as a tool for making whipped cream.

The gas will cause an oxygen deficiency that damages the central nervous system, and many may experience difficulties in walking and gripping objects. However, CGTN’s Sun Tianyuan reports that the laughing gas can be easily purchased in China, and there is no regulation in this field as the gas is not on the restricted substance list.

The product description specifically warns buyers not to use it for recreational purposes, but from comments online, it is clear people are not using it for baking. The price for laughing gas is rather reasonable too, at about 5 dollars for 10 canisters sold on China's biggest online shopping platform, which is totally legal.