
Background: To evaluate the consequences of drug interactions prescribed in the intensive care unit (ICU) of a large public hospital. Methods: Cross-sectional and retrospective study, performed with medical records of patients admitted to the adult ICU of a large hospital in the city of Imperatriz Maranhão, from January to March 2018. The selected patients were older than 18 years, and had a length of stay in the ICU for a equal or superior period of 24 hours and prescription with at least two drugs. Potential drug interactions have been quantified and classified using the MicromedexTM database. Results: The 95 prescriptions included in this study contained 93 different drugs, with an average of 8.87 (± 2.28) drugs per prescription. Potential drug interactions were identified in 94.7% of prescriptions, with an average of 6.33 (± 4.01) interactions per prescription. From the 602 potential interactions identified, important and moderate interactions were present in 65.28% and 26.74%, respectively. The number of drug interactions showed a significant correlation with the number of drugs prescribed and the length of stay in the intensive care unit. Conclusion: Through the accomplishment of this study, it was demonstrated the high prevalence of potential drug interactions in the intensive care unit sector and its clinical consequences for the patient, highlighting the need to implement strategies to increase patient safety.