Nitrous oxide use in first-year students at Auckland University.

In a recent Lancet Case report, a patient presented with subacute combined degeneration of the spinal cord after recreational use of nitrous oxide (N2O). There is very little information about use of this substance as a recreational drug. In a questionnaire-based study, we surveyed 1782 students in their first year at the University of Auckland, New Zealand. 1360 (76%) questionnaires were completed and consistent. 780 (57%) students were aware of recreational use of N2O, 158 (12%) used the substance recreationally, and 39 (3%) inhaled it at least monthly. Users were most likely to be white and to be men. Our results show a high frequency of recreational N2O use in first-year students at Auckland University. Although this study does not accurately reflect use of this substance in the wider community, the high prevalence suggests that presentations of subacute myelopathy in an otherwise fit young person should prompt an enquiry about use of N2O.