not-yet-known not-yet-known not-yet-known unknown Aim: Drug interactions are a significant healthcare concern frequently encountered in intensive care units. Our study aims to acquire more up-to-date data and raise awareness of drug interactions. Methods: A retrospective analysis was performed on the data of 163 patients admitted to the intensive care unit in 2019. The patients’ medication lists were evaluated on a daily basis, and drug information was analyzed using three different online databases: Micromedex, Lexicomp, and Drugs.com. Results: The length of hospital stay ranged from 1 to 50 days, and a total of 1,834 medication orders were analyzed. The most common admission diagnoses were pneumonia, acute renal failure, and gastrointestinal bleeding. Comorbidities were present in 81.6% of patients. The number of interactions increased significantly with increasing comorbidities and number of drugs. This association was particularly evident for cardiovascular diseases. The number of interactions was higher in men. Interactions were identified in 82.9% of orders in Micromedex, 92.5% in Lexicomp, and 95.5% in Drugs.com. The most common contraindicated interaction was between linezolid and tramadol, while the most common major interaction was between aspirin and enoxaparin. Linezolid, fluconazole, and metoclopramide were the most common drugs contributing to contraindicated interactions, while enoxaparin, aspirin, and clopidogrel were the main contributors to major interactions. Albuterol, norepinephrine, and pantoprazole were associated with more moderate interactions. Conclusion: Assessment of drug interactions can lead to improved patient outcomes and avoidance of unnecessary economic burden. Clinicians should use several sources when performing such assessments. There are significant differences between databases.