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Home > Repeated self-harm among young people following hospital-presenting intentional drug overdose.

Millar, Sean (2021) Repeated self-harm among young people following hospital-presenting intentional drug overdose. Drugnet Ireland, Issue 78, Summer 2021, pp. 26-27.

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Background and methods

High rates of self-harm are consistently seen among young people in Ireland and other countries. The incidence of hospital-presenting self-harm peaks among young people, who most often engage in intentional drug overdose (IDO). In addition, the risk of self-harm repetition is also high among young people, with several countries reporting increases in youth self-harm since 2017.1,2,3 These trends are of concern, considering the association between self-harm and increased risk of suicide in young people, with repeated self-harm further elevating this risk. However, little is known about patterns of repetition and method-switching following IDO among young people.

An Irish study4 from 2020 investigated repeated self-harm and method-switching following hospital-presenting IDO among young people. In this research, published in the International Journal of Environmental Research and Public Health, data from National Self-Harm Registry Ireland on hospital-presenting self-harm by individuals aged 10–24 years during 2009–2018 were examined. Cox proportional hazards regression models with associated hazard ratios (HRs), survival curves, and Poisson regression models with risk ratios (RRs) were used to examine the risk factors for repetition and method-switching.


During the period 2009–2018, some 16,800 young people presented following IDO. Of these hospital presentations, within 12 months, 2,136 young people repeated self-harm. Factors associated with repetition included being male (HR=1.13, 95% CI: 1.03–1.24); being aged 10–17 years (HR=1.29, 95% CI: 1.18–1.41); consuming 50 or more tablets (HR=1.27, 95% CI: 1.07–1.49); and taking benzodiazepines (HR=1.67, 95% CI: 1.40–1.98) or antidepressants (HR=1.36, 95% CI: 1.18–1.56). The cumulative risk for switching method was 2.4% (95% CI: 2.2–2.7). Method-switching was most likely to occur for males (RR=1.36; 95% CI: 1.09–1.69) and for those who took illegal drugs (RR=1.63; 95% CI: 1.19–2.25).


The authors discussed how young males were at increased risk of both repetition following IDO and method-switching – often to more potentially lethal methods of self-harm and that benzodiazepines and illegal drugs were associated with risk of repetition and method-switching among young people. They suggest that ensuring the provision of mental health assessments and regulating drug access are key action areas for the prevention of suicidal behaviour among young people.

1   Griffin E, McMahon E, McNicholas F, Corcoran P, Perry IJ and Arensman E (2018) Increasing rates of self-harm among children, adolescents and young adults: a 10-year national registry study 2007–2016. Soc Psychiatry Psychiatr Epidemiol, 53: 663–671.

2   Tyrrell EG, Orton E, Sayal K, Baker R and Kendrick D (2017) Differing patterns in intentional and unintentional poisonings among young people in England, 1998–2014: a population-based cohort study. J Public Health (Oxf), 39(2): e1–e9.

3   Cairns R, Karanges EA, Wong A, et al. (2019) Trends in self-poisoning and psychotropic drug use in people aged 5–19 years: a population-based retrospective cohort study in Australia. BMJ Open, 9(2): e026001.

4   Daly C, Griffin E, McMahon E, et al. (2020) Repeat self-harm following hospital-presenting intentional drug overdose among young people – a national registry study. Int J Environ Res Public Health, 17(17): 6159.

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