Purpose: The purpose of the study is to determine if pharmacologic approaches are effective in prevention and treatment of delirium in critically ill patients. Materials and methods: We performed a systematic search to identify publications (from January 1980 to September 2014) that evaluated the pharmacologic interventions to treat or prevent delirium in intensive careunit (ICU) patients. Results: From 2646 citations, 15 studies on prevention (6729 patients) and 7 studies on treatment (1784 patients) were selected and analyzed. Among studies that evaluated surgical patients, the pharmacologic interventions were associated with a reduction in delirium prevalence, ICU length of stay, and duration of mechanical ventilation, but with high heterogeneity (respectively, I2= 81%, P=.0013; I2=97%, Pb.001; and I2= 97%). Considering treatment studies, only 1 demonstrated a significant decrease in ICU length of stay using dexmedetomidine compared to haloperidol (Relative Risk, 0.62 [1.29-0.06]; I2= 97%), and only 1 found a shorter time to resolution of delirium using quetiapine (1.0 [confidence interval, 0.5-3.0] vs 4.5 [confidence interval, 2.0-7.0] days; P= .001). Conclusion: The use of antipsychotics for surgical ICU patients and dexmedetomidine for mechanically ventilated patients as a preventive strategy may reduce the prevalence of delirium in the ICU. None of the studied agents that were used for delirium treatment improved major clinical outcome, including mortality.2020-08-21