Dr Des Corrigan reviews some disturbing evidence on the effects of N?O on young Irish people
When planning my article each month, I usually have to rely on international research for my evidence base, so it came as a surprise – albeit not a pleasant one, given the subject matter – to come across a number of Irish studies on the harmful effects of nitrous oxide (N?O) on young people here. The Irish research echoes international experience on the need to put in place comprehensive prevention, treatment, demand, and supply reduction strategies.
The earliest of the Irish papers appeared in the Irish Journal of Medical Science in 2023 and featured two cases, both concerning young men admitted to the Emergency Department of St James’s Hospital with progressive neurological dysfunction after exposure to N?O. One of the men remained symptomatic two months after self-discharge, following seven days of intramuscular Vit B12 and folic acid, as well as physio and occupational therapy.
Three reports have appeared so far this year. In January, a team led by a consultant neuroradiologist at Beaumont Hospital published a paper in the American Journal of Neuroradiology describing 33 patients who underwent MRI scans between 2012 and 2024 for sub-acute combined degeneration of the spinal cord (SACD), of whom 25 reported N?O use.
All of what are termed ‘N?O-SACD’ cases occurred between 2021 and 2024. Of the 14 confirmed cases, 100 per cent reported pins and needles (paraesthesia), 52 per cent weakness, and 36 per cent ataxia. All 14 had what is described as a classical ‘inverted V’ or ‘rabbit ears’ sign in MRIs of their cervical spinal cord. All the patients, with a median age of 20, were left with lasting neurological damage.
Neurologists and neurophysiologists from Tallaght University Hospital, TCD, and UCD reported on a retrospective case series of 18 patients with N?O-associated myeloneuropathy in the Irish Journal of Medical Science earlier this year. Some of the patients, who were predominantly male and with a mean age of 20, had used up to 12 x 580g large canisters of N?O for periods ranging from a month to several years. While a few had used oral B12 supplementation prophylactically, it did not appear to be as effective as when delivered intramuscularly. The vast majority had elevated homocysteine levels indicative of B12 depletion. Follow-up data available for seven patients showed that after three months of B12 injections, four had a normal neurological examination but the remainder still showed deficits.
The most recent publication appeared in April in the Irish Medical Journal and came from the Acute Medicine Department at the Mater Hospital looking at Hospital Inpatient Enquiry (HIPE) data from all acute hospitals in the Republic. Over a four-year period, there were 63 inpatient discharges involving N?O misuse or toxicity – of whom 82 per cent had confirmed B12 deficiency. This mirrors the 2025 National Drug Treatment Reporting System data, which detailed 66 patients treated for problematic use of N2O, of whom more than half were under 18.
For the majority, their N?O use was part of a pattern of polydrug use. Given that, overall, a total of 15,422 people were treated for problem drug use, this is a relatively small number. However, it is a number which is growing.
For the majority, their N?O use was part of a pattern of polydrug use
The European Web Survey on Drugs in 2021 recorded that 5.5 per cent of Irish 18-to-24 year-olds who self-identified as a drug user reported N?O use. Worryingly, 28 per cent of them used more than 10 canisters daily, although the size of those was not specified.
As you would expect, higher exposure increases the risks from the gas. A 2023 paper in Practical Neurology noted that 1.9 per cent of those using just one canister reported symptoms compared to 8.5 per cent of those using over 100 canisters at a time. One canister (Silver Bullet or Whippit) delivers 8g of N?O, but recreational users are increasingly moving towards standard cylinders (legally used in the food industry) that contain 580-to-640g of gas – the equivalent of 70-to-80 canisters.
Some users said they used cylinders of medicinal gas (50 per cent N?O/50 per cent O2) – stolen from hospitals – containing either 350 or 500g of N?O. The 2023 report from one UK hospital noted that patients reported using an average of 580 canisters a week, which raises the question of addiction to N?O.
A 2023 paper in Addiction examined this issue, noting reports of tolerance, relapse, obsession with using the gas, and craving for it after periods of abstinence. The authors concluded that, while the evidence was limited, the presence of those four Substance Use Disorder criteria meant that N?O should be treated as potentially addictive until the evidence base is more definite.
A 2025 position paper from the European Federation of Clinical Chemistry and Laboratory Medicine referred to psychiatric symptoms linked to N?O use, including acute anxiety, hallucinations, mood swings, and cognitive complaints.
Their comments were supported by a systematic review of cases of psychosis related to N?O misuse by a team from Barcelona, published earlier this year in Clinical Psychopharmacology and Neuroscience. Using recognised criteria to assess causality, in 20 cases the researchers found that a history of alcohol use and escalation of N²O inhalation preceded the psychotic episodes involving paranoid delusions and hallucinations. First-line inpatient treatment involved abstinence from N?O, then antipsychotics followed by injectable B12 supplementation.
That review also noted immediate harms such as frostbite burns, collapsed lungs, and traumatic brain injury arising from falls due to unconsciousness and/or hypoxia. Memory impairment was also stated to be common. A number of papers report other physical harms, including bladder and bowel incontinence, impotence, urinary retention, and deep vein thrombosis.
In addition, there is the well-documented risk of traffic accidents, which includes drivers who were inhaling the gas from balloons while driving. All in all, using N?O is not the fun, harmless pastime many young people may believe it to be.
So, what can be done in relation to what the European Federation on Clinical Chemistry said was a silent but growing epidemic that has been critically underestimated by the scientific and medical communities? Here, the Oireachtas Joint Committee on Drug Use, in its June 2026 report, included a number of recommendations concerning the supply of N?O products that would safeguard their legitimate catering and industrial uses, while prohibiting the sale of large volume canisters for recreational use – and also prohibit the marketing, branding, or packaging of the gas in a way designed to appeal to young people.
The need for such an approach was highlighted in a 2025 policy paper in The Lancet Public Health that commented on the easy availability of 2kg cylinders in flavours such as pineapple and coconut for which there is no legitimate food use. Some UK vendors, with breath-taking cynicism (pardon the pun), also package the gas along with balloons and B12 supplements.
It is not clear if our present control under the 2010 Psychoactive Substances Act is sufficient or if stronger legislation up to and including the Misuse of Drugs Acts is needed to protect young people.
