Dr. Navin Kumar, an attending Gastroenterologist at Brigham and Women's Hospital, medical educator at Harvard Medical School, and co-founder of the Run the List podcast and host Blake Smith discuss how to approach a patient presenting with diarrhea. In this episode, Navin discusses his framework for thinking through these cases, from patient history to chronicity and quality. Through a case discussion, they review the definition of diarrhea, the broad types of diarrhea (watery, fatty, and inflammatory), and how to further workup these cases using colonoscopy and biopsy. The episode closes with a diagnosis and three clinical pearls, setting the stage for RTL's next episode dedicated to IBD management.