Abstract
Abstract: Irritable Bowel Syndrome is one of the most frequently seen functional bowel diseases. Despite its high prevalence, the etiology and pathogenesis of IBS could not still be explained completely and diagnosing is quite difficult in some cases. IBS, being a multisymptomatic functional gastrointestinal system disease, has a broad clinical spectrum and in general, the symptoms are associated with gastrointestinal dysmotility and visceral hypersensitivity. The true diagnosis is based on four key factors: medical history, physical examination, minimal laboratory tests and colonoscopy or other appropriate tests in some cases. However, a homogeneous pathophysiological pattern has not been defined for IBS and this situation, with a high degree of probability, reflects that IBS is a multifactorial disorder that involves abnormalities in brain-gut interactions, visceral hypersensitivity, intestinal motility and secretion, psychosocial factors, composition of the gut microbiota, disturbed intestinal permeability and low grade immune activity.