Oral liquid dosage forms (OLDFs) are the preferred choice for pediatric patients but often result in dosing errors by parents and caregivers.

This study aimed to investigate the causes of dosing errors in the reconstitution and preparation of OLDFs.

A prospective observational qualitative study was conducted from October to November 2022. Participants were approached and recruited face-to-face by the research team in a university building (classrooms, personal offices, etc.) based on the following criteria: being 18 or older and fluent in French. They were asked to prepare a dose of either amoxicillin (Clamoxyl® GSK®, spoon) or amoxicillin-clavulanic acid (Sandoz®, dose-weight pipette) based on a prescription. After completing the task, participants underwent a micro-phenomenological interview conducted by a trained researcher. Data were analyzed using the Valenzuela Moguillansky and Vásquez-Rosati procedure, and errors were classified according to Reason’s taxonomy.

Seventeen of the eighteen participants were included in the analysis. Fourteen errors were identified, primarily related to the spoon, the patient information leaflets(PIL) and the secondary packaging. The main causes included unclear and poorly visible dosing markings on the spoon, unclear water level markings on the medication bottles, and confusing PILs. Most errors were classified as Rule-Based Mistakes according to Reason’s taxonomy.

This study contributed to the understanding of how the occurrence of errors is multifactorial: there are not only visible errors, but also numerous misunderstandings that may or may not lead to errors. Lived experience proved invaluable in elucidating the cognitive and behavioral factors contributing to these errors and Reason’s taxonomy of errors emerged as useful and applicable in the context of medication administration.