Functional gastrointestinal disorders (FGIDs) encompass a heterogeneous group of disorders, with indistinct underlying pathophysiology. These disorders are considered to result from the interaction of altered gut physiology and psychological factors through the brain- gut axis, where brain and gut symptoms are reciprocally influencing each other’s expression. The presence of chronic gastrointestinal symptoms in absence of any organic pathology is the hallmark of FGIDs. Bowel is the most commonly involved part of the gastrointestinal tract (functional bowel disorders), and abdominal pain or discomfort are among the most evident manifestations. FGIDs are highly prevalent and pose a sizeable burden on health care and society, and impact patients’ quality of life.1-3 The new and updated ROME IV classification4 has redefined functional gastrointestinal disorders as ‘disorders of gut-brain interaction (DGBI),’ and classified them into eight broad categories (Table 1), including the functional bowel disorders (category C) that are further subcategorized into the following: irritable bowel syndrome (IBS); functional constipation; functional diarrhea; functional abdominal bloating/distension; unspecified functional bowel disorder, and; opioid- induced constipation.