BackgroundCaffeine is the most utilised psychoactive drug worldwide. However, caffeine withdrawal and the therapeutic use of caffeine in intensive care and in the peri-operative period have not been well summarised. Our objective was to conduct a scoping review of caffeine withdrawal and use in the intensive care unit (ICU) and post-operative patients. MethodsPubMed, Embase, CINAHL Complete, Scopus and Web of Science were systematically searched for studies investigating the effects of caffeine withdrawal or administration in ICU patients and in the peri-operative period. Areas of recent systematic review such as pain or post-dural puncture headache were not included in this review. Studies were limited to adults. ResultsOf 2268 articles screened, 26 were included and grouped into two themes of caffeine use in in the peri-operative period and in the ICU. Caffeine withdrawal in the post-operative period increases the incidence of headache, which can be effectively treated prophylactically with peri-operative caffeine. There were no studies investigating caffeine withdrawal or effect on sleep wake cycles, daytime somnolence, or delirium in the intensive care setting. Administration of caffeine results in faster emergence from sedation and anaesthesia, particularly in individuals who are at high risk of post-extubation complications. There has only been one study investigating caffeine administration to facilitate post-anaesthetic emergence in ICU. Caffeine administration appears to be safe in moderate doses in the peri-operative period and in the intensive care setting. ConclusionsAlthough caffeine is widely used, there is a paucity of studies investigating withdrawal or therapeutic effects in patients admitted to ICU and further novel studies are a priority.