Involvement of gastrointestinal functional disorder in the management of inflammatory bowel disease

Recent therapeutic advances have yielded higher remission rates than before in patients with inflammatory bowel disease (IBD), while many patients in remission still experience gastrointestinal symptoms. These persistent symptoms could be caused by functional bowel disorders and are associated with increased psychological distress. Patients with IBD may have symptoms like functional gastrointestinal disorders (FGID) even before the disease onset, and distinguishing between disease flare and functional symptoms is often difficult. Gastrointestinal infections such as Campylobacter infection may contribute to the onset of both IBD and FGID. The pathophysiology of FGIDs in IBD is complex and multifactorial, involving genetic predisposition, dysregulation of the gut-brain axis, intestinal dysbiosis, impaired mucosal permeability, and low-grade inflammation. These factors further interact with each other to cause symptoms. Management of patients with IBD who present symptoms of FGIDs requires a multifaceted approach based on the principles of FGID treatment under the premise of complete control of intestinal inflammation. In this review, we discuss the clinical overlap, pathophysiology, diagnostic challenges, and a structured approach for patients with IBD who are complicated by symptoms of FGIDs.