An woman who lost the movement of her legs after inhaling nitrous oxide is urging the government to regulate the retail supply of the gas.

Known on the streets as 'nangs' or 'laughing gas', nitrous oxide has been used as a sedative for pain relief for more than 150 years, but it has also been used as a recreational drug.

Auckland resident Claudia*, 24, says she was using nitrous oxide to numb the pain of a back injury.

"I broke my tailbone two years ago... [I've] been in hospital many times, [but] they never helped.

"One night, my friend [inhaled nitrous oxide], and then I did it too. Then I thought 'hey, it helps with the pain'."

But what she was using for pain quickly became a habit.

"I wasn't using [nitrous oxide] every day, it would be every couple of days.

"But the day that I did do it, I'd be consuming a lot, way too much."

Claudia was consuming extra-large bottles of nitrous oxide, with up to two litres of gas.

Sold through dairies but legal

Nitrous oxide is normally sold to registered dentists and doctors as a pain relief. However, the gas can be also used as a propellant to make whipped cream and it is sold in dairies around the country.

Claudia says she had access to the bottles through dairies in the city centre.

"I went to the point where... I wasn't getting anything out of it. I was just doing it and I didn't get the normal fun effects from it or anything.

"One day, the police found me passed out in my car, but they said they couldn't do much about it, because it was considered self-harm."

In May, she ended up in hospital after losing the movement of her legs.

"I woke up one morning and said 'mum, my hands and my feet are tingly'. Then I woke up the next day and couldn't walk or use my hands," Claudia says.

"I tried to stand up, but then I fell over."

In New Zealand, it is legal to sell canisters for food preparation purposes, but selling for inhalation can lead to up to six months of jail time or a $40,000 fine.

The retail supply of the gas is banned in the United Kingdom, with users facing up to two years in prison and dealers up to 14 years.

In Western Australia, from the second half of 2024, nitrous oxide canisters would only be accessible to registered food and beverage businesses.

'It shouldn't be that easy' to buy - Claudia's mother

Claudia's mother, Merine Le Sueur, says easy access to the gas needs to be addressed.

"I went to the shop the other day to buy hair toner and I got asked for a hairdresser license. Why can't there not be rules around anyone going to buy this product? It shouldn't be that easy for us to just walk in and purchase this.

"People are literally not walking because of it, they are using it without understanding and being educated on its consequences. Who is going to care for those people?"

Currently in a rehabilitation centre trying to walk again, Claudia is urging people to be aware of the consequences of the recreational use of nitrous oxide.

"Do you want to end up paralysed for the rest of your life? Do you want to end up like a vegetable?

"At the end of the day, no one cares about you. They only care about the money you are giving them by buying it."

Hospital seeing more cases of gas abuse

Auckland City Hospital neurology chief resident Shilpan Patel says people need to be aware of the risks.

"Nitrous oxide inactivates vitamin B12, which means that if someone is abusing or inhaling any nitrous oxide, it lowers the amount of active B12 that they have in their body.

"When you have lower levels of B12, it means that parts of the body which are dependent on this, things like your nerves and the nerves in your spinal cord, these things can become damaged."

In the past two years, the hospital had seen an increase in people being admitted due to abuse of the gas, says Shilpan.

"[Nitrous oxide related injury] is definitely something that's becoming more recognised, especially in the last year or two because we've had more presentations.

"We've been doing training for our neurology doctors, our emergency department doctors so that they can recognise people when they come in for nitrous oxide injury, so we can start prompt treatment."

Despite not being addictive, the effects of the gas can influence overuse, says Shilpan.

"What can be addictive is the feeling of euphoria or elation and because of that people want to keep experiencing that symptom again.

"However, it's different from substances like tobacco, which have things like nicotine in it, which cause a chemical addiction."

Although patients can recover, rehabilitation could take time, he says.

"We've studied some of our patients and we've found that they do recover, and over time, the strength and numbness can improve.

"But in a lot of the people that we've been following up, they've taken many months to get better, and some people, six months down the line are still not back to normal.

"So, even though people do recover, it does cause significant damage and significant impairment. It's not something that just recovers within a few days."

Regulation, not ban, the way to go - researcher

In February this year, Students for Sensible Drug Policy Dunedin successfully shut down an online retailer offering 24/7 delivery of nitrous oxide to students.

They say despite not being against the recreational use of nitrous oxide, they acted because the retailer was supplying large quantities of the gas, and delivering it 24/7 to students' houses, increasing the chance of overuse.

"Nitrous oxide is already safer than vaping, but the current lack of evidence-based regulation for recreational use is unnecessarily increasing the harm caused by this substance," said SSDP president Max Phillips.

"It creates a space for predatory retailers to exploit people, mostly students and young people. It encourages the sale of nitrous oxide products in such large volumes they promote overconsumption, which increases the harm caused by these products."

The lack of education around the safe use of the gas for recreational purposes prevented the creation of safer options, he says.

"Such as mandating the sale of nitrous oxide mixed with oxygen for inhalation, which would reduce the recreational effect of nitrous oxide but would massively reduce the risk of hypoxia, or the lack of oxygen provided to the brain."

Former SSDP president and researcher Jai Whelan says banning the gas will only create a black market.

"If people want to use something, they [will] usually going to find a way to get a hold of it.

"If [nitrous oxide] become hyper unavailable because of restrictions, it's likely that black market forces will come into play and try to distribute that drug in an alternative way."

People should have the right to personal autonomy, he says.

"I think having some sort of legal regulation of the [recreational use of nitrous oxide] is a way to go. People won't stop using it because it has become regulated, but what we can do is to educate them on the harms and how to use it safely.

"We could, for example, restrict the sale to specialised stores that are R18 of course, like tobacco and alcohol. We could also sell the product only in small canisters rather than a giant tank."

Suppliers bear responsibility - MedSafe

In a statement, MedSafe group manager Chris James says the regulator is reviewing issues around the gas supply.

"The rules around the sale of nitrous oxide in New Zealand are clear - it is illegal to supply nitrous oxide for inhalation without a prescription.

"MedSafe has previously reminded a number of companies known to sell nitrous oxide of their compliance requirements."

MedSafe can investigate reports of nitrous oxide being sold for recreational use and take action, says Chris.

The agency continues to look at possible improvements to the law around the distribution or sale of nitrous oxide, he says.

"It is MedSafe's opinion that retailers supplying recreational users bear a responsibility for the harm this activity may cause."

*Surname has been omitted for privacy reasons

-RNZ.