Diagnosis and management of IBS in adults.

Irritable bowel syndrome is defined as abdominal discomfort or pain associated with altered bowel habits for at least three days per month in the previous three months, with the absence of organic disease. In North America, the prevalence of irritable bowel syndrome is 5 to 10 percent with peak prevalence from 20 to 39 years of age. Abdominal pain is the most common symptom and often is described as a cramping sensation. The absence of abdominal pain essentially excludes irritable bowel syndrome. Other common symptoms include diarrhea, constipation, or alternating diarrhea and constipation. The goals of treatment are symptom relief and improved quality of life. Exercise, antibiotics, antispasmodics, peppermint oil, and probiotics appear to improve symptoms. Over-the-counter laxatives and antidiarrheals may improve stool frequency but not pain. Treatment with antidepressants and psychological therapies are also effective for improving symptoms compared with usual care. Lubiprostone is effective for the treatment of constipation-predominant irritable bowel syndrome, and alosetron (restrictions for use apply in the United States) and tegaserod (available only for emergency use in the United States) are approved for patients with severe symptoms in whom conventional therapy has been ineffective.