Auckland City Hospital is worried about a sudden increase in patients admitted with severe spinal injury due to abuse of nitrous oxide.
The gas, known on the street as 'nangs' or 'laughing gas', can cause severe nerve damage and B-12 deficiency, but can be easily bought in dairies across the country.
Since March, the hospital has had six cases referred to its neurology department, compared to none in the previous year.
In some of the cases, patients were unable to walk or perform simple movements.
Auckland City Hospital neurology chief resident Shilpan Patel said B12 vitamin deficiency was one of the ways to identify if patients had been abusing nitrous oxide.
"When people come in with particular signs or symptoms of nerve damage, and they're also using nitrous oxide, we can then check their vitamin B12 levels as well as a few other associated tests.
"If those confirm a B12 deficiency, then we can diagnose these people with nerve damage due to nitrous oxide."
Patel said those who already have vitamin deficiency could face serious consequences.
"If you had a condition which may make you deficient in B12 and then you take nitrous oxide recreationally, you would be at a higher risk of having harm from it because your B12 is already low or vulnerable to being depleted."
Nitrous oxide canisters have been used as a sedative and pain relief for more than 150 years, but the gas has become a popular recreational drug around the world.
The metal canisters are due to be banned in the United Kingdom as part of a wider crackdown on antisocial behaviour.
In New Zealand, accessing the gas canisters in shops has proven to be easy due to little or no regulation on its distribution for cooking purposes.
In an article published on the Drug Foundation website, University of Auckland's Centre for Addiction Research associate director David Newcombe said using nitrous oxide was a lot less dangerous than using many other drugs, including alcohol.
"There are some harms that can come with using it, but it has a relatively low potency, and the effects dissipate quickly," he said in the article.
In May, a 19-year-old in Australia was hospitalised after consuming up to two litres of the gas a day.
Patel said the majority of the patients admitted at Auckland City Hospital due to inhaling the gas struggled to walk or to perform simple movements.
"We are concerned with young people using large amounts of nitrous oxide recreationally because the patients who have been admitted with damage from the gas have been quite unwell.
"They've had damage to their spine, and it's left them with significant problems, including being unable to walk."
He said the effects of abusing the use of the gas could sneak up on those with pre-existing conditions.
"Anyone who has a nutrient deficiency or a medical condition which can exacerbate a nutrient deficiency could be badly affected by nitrous oxide use."
Patel said the number of canisters inhaled did not influence the risks of taking nitrous oxide recreationally and small amounts of the gas could still be dangerous.
"We had some patients who were having hundreds of canisters per day for a week or so and we also had a person who had a few canisters in a single session. Both of those people presented with damage to their spinal cord and were unable to walk properly.
"That's been confirmed on their tests, their blood tests and their MRI spine scans as well," Patel said.
'No increase overall' - Te Whatu Ora
Information given to RNZ under the Official Information Act showed in the past year, Te Whatu Ora Canterbury admitted four patients with spinal cord damage due to recreational use of nitrous oxide.
Te Whatu Ora MidCentral - which covers Horowhenua, Manawatū, Tararua and Kāpiti Coast - had one patient admitted in the past year.
Te Whatu Ora Taranaki, Hawke's Bay, Northland, South Canterbury, Waikato, West Coast, Whanganui, Wairarapa and Waitematā have had no admissions related to nitrous oxide abuse, while the other DHBs refused to release the data to RNZ.
"Where there is information available for the patient admissions, there has been no increase compared to previous years," Te Whatu Ora said.
RNZ
