Irritable bowel syndrome (IBS) refers to a complex disorder of the lower intestinal tract. It is mainly characterized by a pattern of symptoms that is often worsened by emotional stress.

It is not the same as inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis.

Irritable bowel syndrome involves a combination of abdominal pain and alternating constipation and diarrhea. There are many possible causes. For instance, there may be a problem with muscle movement in the intestine or a lower tolerance for stretching and movement of the intestine. There is no problem in the structure of the intestine.

Irritable bowel syndrome (IBS) can occur at any age, but often begins in adolescence or early adulthood. It is more common in women. Risk factors may include a low-fiber diet, emotional stress, use of laxatives, having had infectious diarrhea, or other temporary bowel inflammation.

Irritable bowel syndrome is extremely common, but only a small number of people seek treatment.

• Chronic and frequent diarrhea, usually accompanied by pain
• Chronic and frequent constipation, usually accompanied by pain
• Abdominal pain or tenderness
  • Following meals
  • Relieved by bowel movement
  • Intermittent
• Abdominal fullness, gas, bloating
• Abdominal distention
• Nausea and vomiting
• Loss of appetite
• Emotional distress
• Depression

Tests usually reveal no problems. Not all patients require endoscopy, especially if symptoms begin early in life and have been stable. However, patients who have irritable bowel symptoms beginning later in life usually require endoscopy.

Younger patients with persistent diarrhea may require endoscopy to look for inflammatory bowel disease (Crohn's disease or ulcerative colitis). Irritable bowel syndrome, by contrast, is not an inflammatory condition, but the symptoms may be very similar to those of inflammatory bowel disease.

Patients over age 50 should be screened for colon cancer.