Purpose: To assess the effectiveness of additional risk minimization measures (aRMMs) implemented in Europe for colistimethate sodium (CMS) among healthcare professionals (HCPs) and patients/caregivers following safety concerns regarding incorrect use of CMS delivered via Turbospin inhaler., Methods: A cross-sectional study was conducted among HCPs and patients/caregivers in Austria, Denmark, France, Germany, The Netherlands, and the United Kingdom between September 2016 and March 2018. Knowledge of the educational materials was assessed regarding common side effects, correct use of CMS and Turbospin inhaler, and capsule breakage. Awareness, receipt, and utilization of the aRMMs were also evaluated., Results: Among 124 HCPs surveyed, the majority acknowledged awareness (86.2%), receipt (91.0%), and utilization (81.6%) of the CMS educational materials and were knowledgeable about the common CMS side effects (93.2%). Most HCPs correctly answered most questions regarding the proper use of CMS (>90%), yet only half knew how to correctly use the Turbospin inhaler (53.2%). Knowledge about capsule breakage was moderate (67.5%). Of the 29 patients/caregivers surveyed, almost half were aware of the educational materials (48.1%); of these, 69.2% received and used the materials. Most patients/caregivers were knowledgeable about the common CMS side effects (81.5%) and proper CMS use (>85%); however, knowledge about correct Turbospin inhaler use and potential for capsule breakage was moderate to low (48.1% and 37.9%, respectively)., Conclusions: HCPs and patients/caregivers have good knowledge about the common side effects associated with CMS. However, knowledge of correct use of the Turbospin inhaler and capsule breakage was moderate to low., (© 2019 John Wiley & Sons, Ltd.)