We report the case of a patient with severe chronic diarrhea. He was admitted on multiple occasions for this reason, with the cause remaining undetected. After obtaining a detailed medical history and performing several studies, the patient was diagnosed with microscopic colitis and enteropathy due to Olmesartan. In the literature, both diseases appear concurrently only in a few cases. Here we highlight the importance of conducting a comprehensive medical history and maintaining high clinical suspicion to avoid delays in the diagnosis of these uncommon pathologies, as well as unnecessary tests and empirical treatments.