Why nitrous oxide is causing the Government concern, despite being less harmful than kava or vaping

Nitrous oxide is at the bottom of the harm table compared to other drugs – legal or illegal – but as with any substance, it isn’t harmless. Excessive use can lead to cognitive, psychiatric and neurological impairment, and B12 deficiency.

Two worrying trends in particular spurred Health Minister Dr Shane Reti to seek urgent advice earlier this year on what he called “a significant public health issue”.

One was greater access apparently via vape stores, and the other was the use of large canisters that make it much easier to take too much, too quickly – more than 250 times a standard dose in one hit.

Not that the Government introduced anything new. Its crackdown amounts to a clarification that using nangs for fun is illegal and falls under the Psychoactive Substances Act 2013. This means anyone selling it for these purposes can face up to two years’ jail, or for a company a $500,000 fine. Personal possession is punishable by a fine up to $500.

Previously it came under the Medicines Act, given its use as a prescription medicine for pain relief in, for example, medical care. But this was practically toothless because penalties under this law cannot be applied for a substance when it’s not used medically. This is evident in the zero prosecutions for using it recreationally since 2010.

Nitrous oxide canisters are “readily available” in dairies, vape stores, or online, according to a Ministry of Health briefing released to the Herald under the Official Information Act.

There’s no recent data on how much is it used. The 2007/08 New Zealand Alcohol and Drug Use Survey found less than 1% (0.8%) of adults had used nangs in the past year, with 4.6% having used it at all.

More recently, a quarter of the respondents in the 2022/23 New Zealand Drug Trends Survey said they had used nitrous oxide at least once in the past six months, while 56% had used nitrous oxide at some point in their lifetime.

This doesn’t suggest a quarter of the population using it. The respondents are self-selecting, so it suggests usage is common among a quarter of those who know about and use drugs. The rate was slightly lower than for LSD/psychedelics (28%), and more than twice that for cocaine (12%).

According to the 2023 New Zealand drug harms ranking study, which considers over a dozen different harms, the overall harm from using nitrous oxide was the lowest among 23 substances, immediately below kava and nicotine e-cigarettes/vaping. Alcohol was the most harmful, followed by methamphetamine, synthetic cannabinoids, tobacco products, and then opiates.

The ministry briefing outlined the health risks of inhaling nitrous oxide, which typically involves a short period of oxygen deprivation.

“One of the most immediate risks of nitrous oxide use is physical injury due to fainting or falling.”

Others include “loss of consciousness, seizures, and heart problems, especially when inhaled in poorly ventilated areas”.

“Long-term use of large amounts of nitrous oxide can lead to vitamin B12 deficiency, which can cause nerve damage and neurological issues.”

There have been relatively few ACC claims related to nangs, but the number has increased substantially this year: 25 claims so far, compared to 10 claims last year. Since 2019, there have been a total of 51 claims.

This is still a fraction of 275 ACC claims for e-cigarette-related injuries from 2019 to 2022.

In 2005, an expert drug committee decided not to add nitrous oxide as a controlled substance to the Misuse of Drugs Act because it wasn’t considered harmful enough.

Reti emailed the Ministry of Health at the start of August asking for “rapid advice” following concerns over access to nangs from vape stores.

This followed a flurry of nitrous oxide stories in the media including a woman losing movement in her legs, six cases referred to the Auckland City Hospital’s neurology department compared to none in the previous year, and a study that looked at the effects of excessive use on 12 patients, who were admitted to hospital between 2016 and 2023.

In February this year, a group of Dunedin students also successfully shut down an online retailer offering nitrous oxide around the clock.

The ministry replied to Reti on August 8, telling the minister there was no data on any sales from vape stores as retailers didn’t need to report it. Smokefree Enforcement Officers also had no enforcement powers in vape stores because nangs don’t come under the smokefree legislation.

Later that month, the ministry wrote to Reti about “some indication” – mostly anecdotal – that usage and harm were both increasing. This included 10 nitrous oxide reports to the National Poisons Centre so far this year, and 11 reports last year. Most of them showed “a ‘heavy’ use pattern (i.e., acute heavy and/or chronic daily use) and associated neurological symptoms”.

These numbers are low but, again, are a marked increase from the three to five reports a year between 2019 and 2022.

“Police in Waikato and the Bay of Plenty districts report an increase in incidents involving nitrous oxide. These include several car accidents where witnesses or the occupants have admitted to using nitrous oxide while driving,” the briefing said.

“Auckland- and Christchurch-based clinicians have reported a perceived increase in patients experiencing severe harm from consuming large quantities of nitrous oxide in a short space of time. The harm reported ranges from severe spinal injury to psychosis.”

Part of the problem was the emergence of larger canisters, holding up to 3.3 litres, being sold in vape stores. This would hold about 260 times a standard nang dose.

“The National Drug Intelligence Bureau notes that the availability of large canisters appears to be the main difference between recent trends and relatively fewer harm events from nitrous oxide use in the past,” the briefing said.

Enforcement action under the Medicines Act had “proven difficult”, as obtaining evidence could be seen as entrapment.

The only action taken under the Psychoactive Substances Act were cautions from police. “There has not yet been a prosecution.”

Advice to the minister a fortnight later recommended the action that Reti announced later that month. This was for Medsafe to update its advice to say inhaling nangs to get high will be covered under the Psychoactive Substances Act, rather than the Medicines Act.

This immediately makes it much harder for vape stores to sell nitrous oxide canisters legally.

“Asking the customer to declare that a product is not for inhalation does not remove the retailer’s liability under the legislation,” the new guidance says.

“Some retailers have disclaimers that the products are only sold and/or are only to be used for catering purposes ... It is Medsafe’s view that such disclaimers do not protect retailers from their responsibilities to comply with the law.”

Since Reti’s announcement, media stories have suggested ongoing availability of cannisters, including from a bakery after the local vape stores stopped selling them.

The ministry said if nothing has improved in six months’ time, a law change might be necessary. Two options existed – under the Hazardous Substances and New Organisms Act, or amending the Psychoactive Substances Act.

“Both the options will require reprioritisation of the ministry work programmes.”

NZ Drug Foundation executive director Sarah Helm said there was “genuine concern” about reports of selling nitrous oxide to young people, and in very large canisters.

“A B12 deficiency can be quite serious and result in nervous system damage and hospitalisation. Improper use can result in suffocation. So they’re not insignificant harms when used in very large quantities, in particular,” she said.

“It’s irresponsible for retailers to be selling, particularly to young people or in those large quantities.”

She said Reti’s announcement was “quick and pragmatic”, which sends a message to retailers to only sell nitrous oxide for legit purposes or face a hefty fine.

It would be better to codify harm-reduction strategies into the law, she said, such as regulating for low-harm substances in small quantities along with good health advice, and making large canisters illegal.

“That actually might end up being a more efficacious way of going about it.”

Sign up to the Daily H, a free newsletter curated by our editors and delivered straight to your inbox every weekday.

Derek Cheng is a senior journalist who started at the Herald in 2004. He has worked several stints in the press gallery team and is a former deputy political editor.