Diagnosis and treatment of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a chronic functional disorder of the gastrointestinal tract. The exact cause is unknown. The diagnosis should be made on clinical grounds, using symptom-based criteria such as the Manning or Rome criteria, unless symptoms are thought to be atypical. Excluding celiac disease in all patients consulting with symptoms suggestive of IBS is worthwhile, but evidence for performing other investigations to exclude organic disease is not convincing. No medical therapy for IBS has been shown to alter the disease course, and treatment has traditionally been directed towards symptom relief. The aim should be to improve the predominant symptom reported by the patient. Fiber, peppermint oil, or antispasmodic agents are beneficial as first-line therapies in some patients. Where these fail, emerging data have confirmed the efficacy of antidepressants, drugs acting on the 5-hydroxytryptamine receptor, and probiotics in the short-term treatment of IBS. There are a number of novel therapies under development that show promise, including non-absorbable antibiotics, lubiprostone, and linaclotide. This article will provide a summary of diagnostic criteria for IBS, evidence to support investigations to exclude organic disease, and current and emerging therapies in this field.