Introduction: Cystic Fibrosis (CF) requires multiple pharmaceutical treatments, elevating the risk of medication errors (ME), which may compromise patient safety. This study aimed to improve the quality of discharge prescriptions (DPs) using indicators following admissions for IV antibiotics in pediatric CF patients. Methods: This project involved a longitudinal observational retrospective descriptive study followed by a longitudinal quasi-experimental prospective phase between January 2013 and December 2016 in CF patients admitted to a London Children's Hospital. The CF pharmacist reviewed DPs. Six rights of medication administration were defined (6R): dose, drug, frequency, duration of treatment, pharmaceutical form, and route of administration. We classified ME according to 6R, including subtype of error: committed/omitted. We calculated quality indicators by dividing the number of each correct parameter defined by 6R by number of DPs. Retrospective results were used prospectively to describe and implement improvement strategies and safety actions. Results: The retrospective study phase included 42 CF children (100 hospital admissions and 1,343 drugs). The prospective phase included thirty-five children (55 admissions and 822 drugs). The total number of ME identified was 148 (78 committed; 70 omitted) in retrospective phase and 135 (19 committed; 116 omitted) in prospective phase. Quality indicators for drug and dose showed significant improvement after implementing safety strategies. The global quality indicator increased from 22% (retrospective) to 41.82% (prospective), but we did not achieve the previously defined quality standard value (50%). Conclusions: A retrospective review of DP by a CF Pharmacist identified failures in DP quality. Implementing improvement strategies improved prescribing. Integrating pharmacist within multidisciplinary team improves DP reducing errors.