Background: Proper analgosedation is a cornerstone in the treatment of critically ill patients in Pediatric Intensive Care Units (PICUs). Medications, such as fentanyl, morphine, and midazolam, are essential to safe and respectful care. The use of these medications over time may lead to side effects such as iatrogenic withdrawal syndrome (IWS) in the tapering phase. The aim of the study was to test an algorithm for tapering analgosedation to reduce the prevalence of IWS in two Norwegian PICUs at Oslo University Hospital. Methods: A cohort of mechanically ventilated patients from newborn to 18 years with continuous infusions of opioids and benzodiazepines for 5 days or more were included consecutively from May 2016 to December 2021. A pre- and posttest design, with an intervention phase using an algorithm for tapering analgosedation after the pretest, was used. The ICU staffs were trained in using the algorithm after the pretest. The primary outcome was a reduction in IWS. The Withdrawal Assessment Tool-1 (WAT-1) was used to identify IWS. A WAT-1 score ≥3 indicates IWS. Results: We included 80 children, 40 in the baseline group, and 40 in the intervention group. Age and diagnosis did not differ between the groups. The prevalence of IWS was 95% versus 52.5% in the baseline group versus the intervention group, and the peak WAT-1 median was 5.0 (IQR 4–6.8) versus 3.0 (IQR 2.0–6.0) (p =.012). Based on SUM WAT-1 ≥ 3, which describes the burden over time better, we demonstrated a reduction of IWS, from a median of 15.5 (IQR 8.25–39) to a median of 3 (IQR 0–20) (p = <.001). Conclusion: We suggest using an algorithm for tapering analgosedation in PICUs since the prevalence of IWS was significantly lower in the intervention group in our study.