
Known as "Nos", "nangs" or "laughing gas", nitrous oxide in canisters can be used to make whipped cream, and until recently, it could be easily bought in dairies across the country.
For more than 150 years, it has been used as a sedative for pain relief, but it is now used as a recreational drug.
The gas can be inhaled to create short-lived psychoactive effects, such as euphoria, dissociation and hallucinations.
Auckland City Hospital expressed concern in 2023 about a sudden increase in patients admitted with severe spinal injury due to abuse of nitrous oxide.
It can cause severe nerve damage and vitamin B12 deficiency, and in some cases, it left patients unable to walk or perform simple movements.
One particular patient had to spend time in rehabilitation, learning how to walk again.
In New Zealand, it is illegal to sell, supply or possess the drug for recreational use.
Lead author and University of Otago (Christchurch) population health postdoctoral research fellow Jai Whelan said his latest research showed there should be little cause for "serious large-scale concern", despite its use for non-medical purposes growing globally and harm resulting in hospitalisations.
"There was, and still is, very little information about its use in Aotearoa.
"We wanted to start filling that gap and assess what harms may be out there so that we can shape our harm reduction measures ... [for] people who use drugs."
Nearly 1000 people across New Zealand, aged 16-65, were surveyed for the study, he said.
Consumption practices, experiences of harm, and harm reduction behaviour were investigated across 466 respondents, while nitrous oxide knowledge, perceptions of use and views on legality were explored in an additional 510 people who did not use nitrous oxide.
"For most people who consume nitrous oxide, use is infrequent, in low doses, and mainly used in addition to other drugs.
"Harm was relatively uncommon," Dr Whelan said.
Those who had used nitrous oxide (60.5%) reported knowing "a moderate amount" or more about the drug, but just 28.1% knew about its ability to inactivate the B12 vitamin.
He said less than half of consumers (47.4%) experienced adverse effects — the most common were confusion (31.6%), cold burns (24%) and nausea (15.7%).
Just under 6% said their nitrous oxide use had caused them harm.
A minority of people also reported feeling consistent numbness, which may have been caused by its impact on vitamin B12.
He said this could be a rare sign of more serious harm, mostly associated with chronic and heavy use.
"We would recommend that if anyone experiences this or other sensory changes that remain after the drug has worn off, they should take a break from using nitrous oxide and seek medical attention."
In September 2024, former health minister Shane Reti announced the government planned to restrict sales of nitrous oxide and supported the introduction of tougher penalties if sold for recreational purposes under the Psychoactive Substances Act 2013.
However, Dr Whelan said "our results show little cause for serious large-scale concern and point to some clear next steps around drug education".