Demographic characteristics and repeat overdose risk factors in 601 patients with intentional drug overdose in the emergency department: a cross-sectional study

The majority of patients were female (70.4%) and adolescents or young adults aged 10-29 years (72.2%), with a median age of 22 years. Overall, IDO cases demonstrated seasonal peaks in autumn and spring, accounting for 61.6% of presentations. Age-stratified analyses revealed significant seasonal variation (χ² = 27.064, <i>p</i> = 0.008), with adolescents and young adults showing a pronounced autumn peak (both >35%), whereas middle-aged adults (45-59 years) exhibited a relative summer peak. Medication-related poisoning accounted for 96.7% of cases, primarily involving antipsychotics and sedative-hypnotics, while pesticide poisoning comprised 3.3%. A history of prior self-harm was independently associated with repeated IDO (OR = 26.66, 95% CI: 11.17-63.61, <i>p</i> < 0.001). Conclusion: Patients presenting with IDO in the emergency department were predominantly adolescents and young adults, with a higher proportion of females. Overall presentations peaked in autumn and spring, largely driven by younger age groups. A prior history of self-harm was independently associated with repeated IDO. Emergency nurses should routinely assess self-harm history, prioritize early identification and intervention among high-risk adolescents and young adults, and strengthen integrated "emergency-psychiatry-community" care pathways to reduce recurrence.