The UK government has announced the possession of nitrous oxide, or laughing gas, will soon become a criminal offence. But how dangerous is it? David Nutt, the Edmund J Safra Professor of Neuropsychopharmacology at Imperial College London, explains the drug’s effects, its current legal status and the associated risks of using it.
What is laughing gas?
Nitrous oxide, or laughing gas, is a Great British invention. It was discovered in 1780 by Joseph Priestly in Birmingham and then tried by president of the Royal Society Sir Humphry Davy. After inhaling it from a silk bag, Davy reported he “lost touch with all external things”, entering a realm of pure thought which he described as a ”world of newly connected and newly modified ideas”. He was so taken by this effect of the gas that he even started a new branch of science based on these insights he called chemical philosophy.
The recreational aspects of laughing gas then dominated its use for the next 50 years. Posh people hosted laughing gas parties and demonstrations were given in music halls where customers could volunteer to try it. Some of them fell off the stage but reported they did not feel pain and this observation led to nitrous oxide becoming used as an anaesthetic. Now, 170 years later, it still is, especially for childbirth and re-setting dislocated joints and broken bones. This is probably the first and only example of a music-hall trick leading to medical advancement.
Why is it back in the news?
In the past 20 years recreational use of nitrous oxide has again become popular. There seem to be several reasons for this. One is that it is now readily available in small metal canisters called whippits that are used in the catering industry to froth creams: the user opens the whippit, fills a regular party balloon with the escaping gas and then inhales the gas from the balloon.
A lot of the antipathy towards nitrous oxide in recent years is because users often throw away the used whippits, littering streets and parks where they look unsightly and people can slip over on them.
The drug’s upsurge in popularity has led to repeated calls to bring in legal measures to tackle its use as a recreational drug. The latest is being led by Home Secretary Suella Braverman who has branded use of the drug “unacceptable”. Currently, like alcohol, it is illegal to sell nitrous oxide to anyone under the age of 18. It is also illegal to sell it (or 'deal' it) for recreational purposes, but personal possession or use is not currently illegal.
How harmful is nitrous oxide?
All experts agree that nitrous oxide scores low on ratings of risk and harm and it rarely causes death. But it isn’t completely harmless, especially if used excessively. Aside from short-lived unwanted effects such as nausea, confusion and accidents, which are more common when it’s taken with other substances, the biggest risk is that it can cause nerve damage because it depletes levels of vitamin B12, which helps nerves to work properly.
The first signs of this are persistent numbness or tingling around the tongue or lips, feet and fingers that can then progress to pain and paralysis of the nerves or even the spinal cord. Note that vegans often have low B12 levels so are more at more risk.
The vast majority, around 70 to 80 per cent, of people who use nitrous oxide do so fewer than 10 times a year and use about five balloons. This moderate consumption reduces the risk of harm and gives the body time to replenish vitamin stores.
But some heavy users can damage their nerves so severely that they end up in wheelchairs. This wasn’t very common in the days when all people used balloons filled from whippits. But recently, as the police have clamped down on the sale of these, users have moved to large industrial cylinders.
These contain large amounts of nitrous oxide - equivalent to hundreds of whippits - so it’s easier to use much more gas in any one session. Also, when someone is inhaling nitrous oxide, they aren’t taking in air, so too much continuous gas intake could starve their brain of oxygen in the same way as if they were suffocating.
Dependence on nitrous oxide as such has not been seen, but a small number of people have reported compulsive use and so are at greater risk of nerve damage and other complications of vitamin B12 deficiency such as heart problems and anaemia.
Inhaling directly from a whippit can also be dangerous as it can freeze the user’s mouth. A final important safety concern is users who drive while under the influence of nitrous oxide – this is illegal and very dangerous.
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