Dr Elizabeth Ogunjimi, Psychiatry Registrar at the HSE Youth Drug and Alcohol Service, highlights the risks — including of death — associated with the use of nitrous oxide, also known ‘laughing gas’ or ‘hippie crack’
There has been an increase in the use of nitrous oxide (N2O or laughing gas) for intoxication purposes during the Covid-19 pandemic whereby large quantities of steel bulbs or whippets were found to litter public places such as parks and green spaces. In the last two decades, the use of N2O is rapidly increasing especially in the dance and festival scenes. In 2019, data collected by the Health Service Executive (HSE) and Trinity College Dublin at music festivals in Ireland indicates that over a quarter of respondents had used N2O.
In the United Kingdom, N2O is the second most popular recreational drug after cannabis. From 2001 to 2016, some 34 deaths were registered in England and Wales, where N2O was implicated.
In Ireland, as in most countries, N2O is a legal substance that is widely available and cheap. It is used as combustion fuel in car racing and rocket engines and also in the food industry as a propellant in whipped cream dispensers, referred to as whippets. It is also used in minor surgeries for its anaesthetic and analgesic properties since its first use in 1844. The mechanism of action for the analgesic and anaesthetic effects are not fully understood.
When inhaled for intoxication purposes, the desired euphoric and dissociative effect is similar to ketamine. Users report a rush of heightening consciousness, disassociation, excitement, deep ‘silly’ voice, sound distortion and dizziness. These have a rapid onset, peak after about one minute of inhaling and dissipate after two minutes of the last inhalation. Some users report that effects can be felt for up to 30 minutes after last inhalation. N2O is commonly used with other drugs, to enhance the effects or intensity. The user may experience psychological dependence.
On the street, N2O is referred to as ‘charger’, ‘hippie crack’, etc and its use as an inhalant substance is referred to as ‘nagging’ or ‘nanging’. Given its use in medicine, the Health Products Regulatory Authority (HPRA) provide guidelines on use of N2O.
However, it can still be purchased from online retailers (i.e. Amazon, eBay, Wish) and specialist stores. Although N2O is not scheduled in the Misuse of Drugs Act, the supply of N2O as a recreational drug is illegal under the Criminal Justice (Psychoactive Substances) Act (CJPSA), 2010. Under the CJPSA 2010 the sale or supply of any psychoactive substance for human consumption is deemed a criminal offence.
The 8 grams steel bulbs (or whippets) contain 10ml of pressurised N2O in liquid form and costs less than a €1 per bulb (or €44 for a pack of 50), the dispenser (or cracker) is about €4 making this a relatively low-cost drug. For recreational use, the bulbs are mostly released into a balloon using the metal cracker. Larger professional canisters containing 3-5L of pressurized N2O are also used to fill balloons.
At room temperature nitrous oxide is a colourless, non-flammable gas that is slightly sweet smelling and tasting. Medical grade N2O and nitrous oxide in bulbs intended for home use is at least 99 per cent pure, whereas N2O used in car racing is usually contaminated with toxic hydrogen sulphide and should thus not be consumed. Some imported whippets have been suggested to contain impurities.
N2O toxicity has been documented since the 1950s for both patients and professionals exposed to it. Many safety measures have been put in place to reduce this risk since then. The ready access that dentists and other professionals have to N2O toxicity is concerning given the many reports of N2O misuse and abuse in this population. N2O abuse is now more widely recognised in the dental community as a serious occupational hazard, present in up to 5 per cent.
Abuse or even occupational N2O exposure, can disturb lipid synthesis in neurons and cause vitamin B12 (cyanocobalamin) deficiency by oxidising the cobalt.
Multiple case studies have reported myelopathy, myeloneuropathy and subacute combined degeneration and psychosis successfully treated with vitamin B12 in abusers of N2O. Other medical effects included pneumomediastinum, pulmonary embolism, pneumothorax has no definite explanation except by its nature N2O displaces other gases in lungs over 30 times faster (low blood-gas partition coefficient).
Several deaths are associated with the use of bags put over the head in order to facilitate inhalation and inhalation in closed spaces. Death related to N2O inhalation from case studies and medical examiner records includes hypoxia and asphyxiation. Although nitrous oxide does not depress the respiratory centre significantly, the normal physiological response to hypoxia is blunted when over 50 per cent concentration N2O is given.
There is evidence for cardiovascular complication or mortality with its use. Frostbite can occur by contact with the nitrous oxide canister for a prolonged period.
Considering the increased use of N2O in recent years, it is important that doctors and other clinical staff maintain an index of suspicion and actively ask young people about their use of this substance. Where use is reported, a brief intervention including some psychoeducation of potential risks is warranted.
Where use is persistent and problematic, a referral to a specialist addiction service may need to be considered.
For further information on N2O and updates on new trends in drug use in Ireland see www.drugs.ie.
- Garakani, A., Jaffe, R. J., Savla, D., Welch, A. K., Protin, C. A., Bryson, E. O., and McDowell, D. M. (2016). Neurologic, psychiatric, and other medical manifestations of nitrous oxide abuse: a systematic review of the case literature. The American Journal on Addictions, 25(5), 358-369.
- van Amsterdam, J., Nabben, T., and van den Brink, W. (2015). Recreational nitrous oxide use: prevalence and risks. Regulatory Toxicology and Pharmacology, 73(3), 790-796. www.drugs.ie.