The aim of this study was to examine adverse reactions to the withdrawal of opioids and benzodiazepines among critically ill children. Although withdrawal reactions have been well documented in relation to substance abusers and their newborn infants, there has been little study of this phenomenon as an iatrogenic problem. We developed a graphical case study method for examining patterns over time, and applied this to five cases referred to us by the nursing staff of a 10-bed paediatric intensive care unit. A striking pattern of behavioural distress was clearly associated with the diminution of opioids and benzodiazepines. These adverse reactions were characterized by various combinations of inconsolable crying, tremors, jitteriness, irritability, gagging, vomiting, and feeding problems. These signs appeared as early as 1 h and as late as 24 h following a significant reduction in opioid and benzodiazepine infusion rates, sometimes following very short-term therapy. We elaborate an interpretation of this distress, in light of the multiple disruptions undergone by critically ill children, and conclude by outlining our recommendations for preventing/minimizing these adverse reactions.