Introduction Poisoning is the 4th leading cause of unintentional injury in children aged under-5 years. The study objective was to determine the factors associated with unintentional poisoning among children under-5 years of age, reporting to emergency rooms (ERs) of tertiary care hospitals in Karachi, Pakistan.

Methods A matched case-control study was conducted on 120 cases and 360 controls. Children with unintentional poisoning were included in the study as cases. For each case three control children matched for age and gender with complaints and diagnosis other than poisoning were selected from the same hospitals ER within 48 h of case identification. Parents were interviewed using structured questionnaires containing information on socio-demographic factors, child's behaviour, and storage practices. Conditional logistic regression was performed to analyse the data.

Results Accessibility to hazardous chemicals and medicines due to unsafe storage (OR 5.6, 95% CI 1.9 to 16.7), child's behaviour reported as hyperactive (OR 8.2, 95% CI 4.6 to 16.1), storage of kerosene oil and petrol in soft drink bottles (OR 3.8, 95% CI 2.0 to 7.3), low socio-economic status (OR 9.2, 95% CI 2.8 to 30.1), low mothers educational status (OR 4.2, 95% CI 1.8 to 9.6) and history of previous poisoning (OR 8.6, 95% CI 1.7 to 43.5) were all independently related to unintentional poisoning.

Conclusion The factors associated with unintentional poisoning in young children are modifiable Key health messages on the safe storage of chemicals and medicines and the use of child resistant containers may help in decreasing the burden of childhood poisoning.