Background: We aimed to investigate changes in the clinical characteristics of pediatric poisoning patients who visited the emergency department (ED) before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: Poisoning cases below age 18 who visited the ED from January 2018 to December 2021 were retrospectively analysed. The study period was then divided into pre-COVID-19 and COVID-19 pandemic to compare poisoning patterns. Results: During the study period, 86,153 visits to the pediatric ED had been recorded, with 625 patients being included the final analysis. During the COVID-19 period, the proportion of poisoned patients increased from 0.62% to 0.98%. The average age of the patients was higher in the COVID-19 period, with 53.4% of the cases being intentional (pre-COVID-19, 32.5%; P < 0.001). Moreover, 70.4% of poisoning cases during the COVID-19 period were caused by drugs (pre-COVID-19, 60.6%; P = 0.038). More patients underwent decontamination and laboratory investigation during the COVID-19 period than during the previous period (P= 0.007 and P < 0.001, respectively). The length of ED stay and the proportion of hospitalisation were significantly greater during the COVID-19 period. After analysing accidental poisoning cases, we found that antipyreticsonsteroidal anti-inflammatory drugs and respiratory drugs were more common in the pre-COVID-19 group, whereas iron/vitamins, cardiovascular drugs and hormones were more common in the COVID-19 group. After analysing intentional poisoning cases, we found that 73.6% and 76.4% of the patients in the pre-COVID-19 and COVID-19 group had a history of psychiatric disease, respectively. Although no difference was observed in the frequency of previous first suicide attempts, 19.0% of the patients in the COVID-19 group attempted suicide more than three times. Conclusion During the COVID-19 pandemic, intentional poisoning cases, especially in adolescence, increased and were treated more. Many of the patients with intentional poisoning had a history of mental illness or suicide in the past. Therefore, it seems that policy consideration for mentally vulnerable adolescents during this new pandemic period is necessary.