Nong was both nervous and curious the first time she tried laughing gas. It came in a little canister. “Take a deep breath, drain all the air from your lungs, and suck in the gas immediately,” she was told. Two seconds later, she felt a rush of exuberance and a little dizziness.

“I was definitely sitting in a chair and holding the armrest, but I still felt like I was falling down,” the 21-year-old told Sixth Tone. The feeling lasted less than 20 seconds, and Nong inhaled several more canisters to maintain the high.

Nong was experiencing nitrous oxide — more commonly known as laughing gas. The gas is used in medicine as an anesthetic, in cooking to whip cream, and in Chinese nightlife as a party drug. Laughing gas is legal, but also addictive and potentially harmful. Nong, like other interviewees, refused to reveal her full name because she didn’t want her family to know about her experiences with the gas.

Nitrous oxide is usually consumed via canisters called “chargers” that are used for whipped cream, or breathed in from balloons the way helium is inhaled. Chargers, roughly the size of a finger, can be bought online starting at 3 yuan ($0.45). They’re considerably more expensive when bought at a nightclub or karaoke bar.

Nong had her first taste of laughing gas at a café and bar in Nanjing, capital of eastern China’s Jiangsu province, where she and her then-boyfriend worked. In April, one of their regular customers — the café served mostly university students — brought a box of chargers and encouraged them to try the gas.

“He told me that laughing gas is very popular now, and many people inhale this stuff at other bars,” Nong said. The customer said he wanted to partner with the café to sell laughing gas, emphasizing that it was legal and promising sizeable profits. But Nong refused.

In late June, Nong felt vindicated in her decision when she read an article circulating on social media. A Chinese college student studying in the U.S. described how nitrous oxide had ruined her life: “In the end, I came out of the Beijing Capital International Airport in a wheelchair,” read the headline. Her frequent use of laughing gas resulted in nerve damage, leaving her temporarily incontinent and unable to walk, among other complications, reported The Beijing News. The report also mentioned the case of an 18-year-old boy who had become permanently disabled after inhaling laughing gas.

“[Compared with other drugs,] it’s cheap, it’s easy to get, and it gives people a wonderful feeling that only lasts for one or two minutes,” Adam Winstock, a consultant psychiatrist and addiction medicine specialist who founded the Global Drug Survey, told Sixth Tone. The gas is safe in small doses, he said, “but because people think it’s very safe, some people of course could run into problems.” Excessive inhalation of nitrous oxide can lead to a vitamin B12 deficiency and cause nerve damage.

According to the Global Drug Survey’s 2015 report, laughing gas has become popular worldwide. In the U.K., where nitrous oxide is illegal to sell but legal to possess, it was the fourth most used drug.

In China, knowledge of laughing gas is limited, and there are no statistics on how many users end up needing medical treatment. According to a neurological study by researchers from a Chinese hospital published in August 2016, many doctors have limited knowledge of the side effects of laughing gas, meaning it is rarely identified as a cause of symptoms in clinical cases.

Huang Jian, a doctor at Peking University Sixth Hospital, one of China’s top mental health hospitals, told Sixth Tone that people can become physically or psychologically dependent on laughing gas. “It’s like taking drugs: People will get addicted and will have strong physical withdrawal reactions,” he said.

Huang added that the popularity of laughing gas is tied to increased use of other drugs, such as methamphetamine and ecstasy, as many people use the gas in combination with other highs. Despite concern from doctors, the latest lists of narcotic and psychoactive drugs — issued by the China Food and Drug Administration in 2013 — do not include nitrous oxide among the more than 200 types of substances defined as drugs.

According to the viral article that Nong came across in June, the author was studying in Seattle and had her first taste of nitrous oxide in 2015, when she saw friends sharing photos of their experiences inhaling the gas from balloons and became curious. “It was new to me. I had never smoked or drank alcohol,” the young woman wrote. She became addicted and would always relapse when she tried to quit. “During those months, I spent hundreds of thousands of yuan on this meaningless and evil thing, and even now, I still can’t walk by myself,” she wrote.

Use of laughing gas is widespread among Chinese students abroad. Jacklyn, a 25-year-old graduate student in New York, told Sixth Tone that inhaling balloons filled with nitrous oxide has been popular among her friends for two years. “It’s everywhere,” she said. Jacklyn doesn’t recall how the fad started, but she said that soon enough, everyone in her circle of friends had tried the balloons. “If you didn’t try it, you would be made fun of as a coward,” she said.

Jacklyn regarded this pressure as part of the “competition” to show off: The students’ families in China are rich, allowing them to afford apartments in Manhattan, designer clothes, luxury bags, dinners at Michelin-starred restaurants, and frequent nightclub visits. 

But both Jacklyn and another student living in the U.S. who requested anonymity told Sixth Tone that laughing gas is not as popular as it once was among overseas Chinese. Yet when Jacklyn returned to China, she found that it was the latest trend in Shanghai and Beijing. “You can see people selling balloons and using boxes of chargers,” she said. “The market in Shanghai is crazier than in New York.”

In January, police in Nanjing published an article describing the difficulties in cracking down on laughing gas use. The market is opaque, the article said, in part because there are no regulations on the production and distribution of nitrous oxide.

Since the June article by the overseas college student brought more attention to laughing gas, online sellers have become less overt in their operations. Many sellers on Taobao, China’s biggest e-commerce website, have taken the words “laughing gas” off their pages and now pretend to be selling whipped cream chargers alongside other kitchen supplies, like coffee makers and baking tools. But these online retailers’ public sales figures for the past month show that they sold thousands of chargers and nothing else.

Some sales are made in chat groups on messaging app QQ. One seller told a Sixth Tone reporter posing as a client that he had several types of cream chargers available: one domestic brand with a lower purity — referring to the proportion of nitrous oxide — and another three imported varieties with a higher purity. He said he was a supplier for several cafés and nightclubs in Nanjing, which sometimes sell chargers for double the price.

Jacklyn no longer uses laughing gas but has fond memories of her experiences. The youngest person she saw take laughing gas was 15; the boy inhaled gas from four chargers at the same time. “It was so cool, you know — it was really awesome!” Jacklyn recalled. “We all thought he was so great.”

None of them took their frequent use of laughing gas seriously until one of Jacklyn’s friends was hospitalized after inhaling too many chargers at home. “Nobody knew how many he had consumed,” Jacklyn said. “The empty chargers were all over the ground, and he even lost consciousness.”

Editor: Kevin Schoenmakers.

(Header image: Nitrous oxide canisters and packs of balloons are displayed outside Parliament Square in London, Aug. 1, 2015. Justin Ng/IC)