<unk>  <unk>  is a functional<unk>  disorder characterized by abdominal pain and alteration of<unk>  habits.<unk>  is caused by the complex interaction of various factors such as intrinsic gastrointestinal factors, CNS dysregulation, psychosocial factors, genetic and environmental factors. Intrinsic gastrointestinal factors include motor abnormalities, visceral hypersensitivity, immune activation, and mucosal inflammation, altered gut microbiota and abnormal serotonin pathways. A definite cause of<unk>  <unk>  has not yet been established. However, an interplay of several factors contribute to the development of<unk>  such as emotional disturbances, stress, adverse early life events, history of inflammatory<unk>  disease, and acute gastrointestinal infections.<unk>  <unk>  may be classified according to Rome IV criteria into four sub types/groups:<unk>  with predominant constipation,<unk>  with predominant diarrhea,<unk>  with mixed<unk>  habits, and unclassified<unk> . In addition,<unk>  occurring secondary to GI infections is known as post infectious-IBS or PI-IBS.<unk>  must be differentiated from other diseases that cause diarrhea, constipation, and abdominal pain, such as celiac disease, inflammatory<unk>  disease (Crohn's disease and ulcerative colitis), thyroid disease (hyper or hypothyroidism), strictures due to ischemia, diverticulitis or ischemia, among others. The diagnosis of<unk>  depends on the recognition of gastrointestinal symptoms that wax and wane and are exacerbated by psycho-social stress. Therefore, the diagnosis of<unk>  is based primarily on clinical symptoms and elimination of other organic gastrointestinal diseases. This is due to lack of definitive radiologic or laboratory diagnostic tests in<unk> . There are no strict guidelines for the treatment of<unk>  and the therapy is mostly symptom-based. All<unk>  patients are required to adapt a diet low in fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs). A psychiatric referral and regular exercise are very helpful for all<unk>  patients. Pharmacological therapy is adjunctive and only preferred in patients where symptoms of<unk>  are moderate-severe in intensity and markedly impair the quality of life. Pharmacological therapy administered to patients is based on the predominant symptom, with diarrhea-predominant, constipation-predominant, and pain-predominant subtypes having their own different regimens. New therapies such as herbal medications, tight-junction modulators, mast cell stabilizers, acupuncture, and mind body therapy currently have an uncertain role in the treatment of<unk> .
Irritable bowel syndrome
Allergic colitis
Crohn's disease
Drug-induced colitis
Ulcerative colitis
Inflammatory bowel disease
Pseudomembranous colitis
Tropical sprue