Many patients admitted to intensive care units consume long-term medication. New drugs may be commenced during intensive care intended for the short term or longer. Patients are often cared for by several teams during hospital admission and long-term medication may inadvertently be permanently discontinued. Following admission, new therapies relevant only in the short term could be continued beyond intensive care and hospital discharge. We conducted a retrospective analysis of drug prescription by examining patients' notes and charts before, during and after intensive care admission. Of 197 drugs prescribed up to intensive care admission to 59 patients, 112 (57%) were stopped. Ninety-nine of these were not reintroduced by intensive care discharge and 34 were not reintroduced by hospital discharge. Of 154 drugs commenced during intensive care, 96 (62%) had no listed reason for their introduction. Twenty-eight were continued beyond hospital discharge, some without apparent ongoing indication. Reliable mechanisms to prevent prescription errors are required.