Medication errors are one of the causes of iatrogenic medication use in children. The POPI tool for detecting inappropriate drug prescriptions and prescription omissions in paediatrics was the first tool to be published in this field in 2014. Our aim was to update the POPI tool for French use based on current recommendations and practice. Criteria were removed, updated or added based on recommendations from learned societies and national bodies. The two-round Delphi method was used to reach a consensus of experts. The level of agreement of the healthcare professionals' proposals was rated on a 9-point Likert scale. In the first round, only proposals with a median agreement of 7 to 9 and an agreement of more than 65% were retained. In the second round, only those with a median agreement of 7 to 9 and over 75% agreement were retained. The POPI tool now includes eight categories (various, infectiology, gastroenterology, pneumonology, dermatology, neurology/pedopsychiatry, haematology and excipients). All the criteria were supported by bibliographical references. They were submitted to 20 French healthcare professionals: 9 pharmacists and 11 doctors (17 hospital-based and 3 self-employed). After two rounds of Delphi testing, 166 criteria were retained and validated (111 inappropriate prescriptions and 55 omissions). In conclusion, this study made it possible to update the POPI tool, which is still available for assessing paediatric prescriptions.