Possession of nitrous oxide, one of the most popular drugs among 16- to 24-year-olds, could be criminalised after the home secretary ordered experts to review its effects. Priti Patel said she was ready to “take tough action” on the widespread use of laughing gas, which is taken mostly through balloons filled from small metal cylinders often seen littering areas around nightclubs and music festivals. More than half a million 16- to 24-year-olds – almost one in 10 – reported taking the drug in 2019-20 and Patel has asked the independent Advisory Council on the Misuse of Drugs (ACMD) to review its harms. Only last July the government said it had no plans to criminalise possession of the gas, which is widely available online to produce whipped cream. Supply of nitrous oxide for its psychoactive effects is already illegal under 2016 legislation to crack down on legal highs, but if possession were to be criminalised it would probably bracket the substance with cannabis and other illegal narcotics. Online catering suppliers currently warn customers it is illegal to use nitrous oxide for its psychoactive properties by inhaling the gas. The Royal Society for Public Health immediately opposed Patel’s move, warning it was not clear that criminalising possession had any effect on a drug’s level of availability or use. “The government’s insistence on criminalisation and incarceration for minor drug offences worsens problems linked to illicit drug use, including social inequality and violence,” said Burcu Borysik, head of policy at the charity. “The heavy-handed enforcement approach to drugs does nothing but spread fear among young people, prevents them from seeking the support they need, and unnecessarily drags them into the criminal justice system.” The drugs charity Release warned the proposal could saddle tens of thousands of young people with criminal records “which will affect their employment and educational opportunities, something that seriously outweighs the harms of nitrous oxide”. But the Home Office said laughing gas “can cause serious long-term effects such as vitamin B12 deficiency and anaemia. It is also commonly used at antisocial gatherings and leads to widespread littering in public places, bringing misery to communities.” Patel said: “Misusing drugs can have a devastating impact on lives and communities. We are determined to do all we can to address this issue and protect the futures of our children and young people.” In 2015, the then chair of the advisory committee, Prof Leslie Iversen, told the home secretary at the time, Theresa May, that possession of laughing gas should remain legal. The committee described how the gas “induces a brief period of euphoria, which may be accompanied by ‘tears of joy’. This appears to be due to a brief activation of opiate systems in the brain.” It said deaths were rare – only six in the UK at the time – and these appeared to be related to asphyxiation caused by a lack of oxygen. It found few if any short-term adverse side-effects. Patel’s move is likely to restart an age-old debate about prohibition of psychoactive substances, especially in the context of the widespread use and misuse of alcohol. Deaths from alcohol-specific causes rose to 7,423 in England and Wales in 2020, according to the Office for National Statistics, and in 2018-19 more than one in 10 incidents of antisocial behaviour were attributed to alcohol. This summer, Tower Hamlets council in east London started threatening £100 fines against people who use nitrous oxide and engage in antisocial behaviour. It introduced a public space protection order related to the drug, citing problems with littering, noise nuisance and vandalism, as well as “health concern and … other associated harms”.