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.

IBS involve 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.

It is not clear why patients develop IBS, but in some intances, it occurs after an intestinal infection. This is called postinfectious IBS. There may also be other triggers.

IBS can occur at any age, but often begins in adolescence or early adulthood. It is more common in women. The condition is the most common intestinal complaint that leads to referral to a gastroenterologist.

Symptoms range from mild to severe, however most people have mild symptoms. IBS symptoms may be worse in patients with underlying stress or mood disorders such as anxiety and depression, but it is important to understand that these conditions do not cause IBS. Symptoms may include:

• Abdominal distention
• Abdominal fullness, gas, bloating
• Abdominal pain or tenderness that:
  • Comes and goes
  • Goes away after a bowel movement
  • Occurs after meals
• Chronic and frequent constipation, usually accompanied by pain
• Chronic and frequent diarrhea, usually accompanied by pain
• Emotional distress
• Depression
• Loss of appetite
• Nausea and vomiting

Most of the time, your doctor can diagnose IBS without ordering many tests. Tests usually reveal no problems.

Some patient may need an endoscopy, especially if symptoms begin later in life. Younger patients with persistent diarrhea may need this test to look for inflammatory diseases that can cause similiar symptoms such as Crohn's disease or ulcerative colitis. You may need additional tests if you have blood in your stool, weight loss, or signs of anemia.

Patients over age 50 should be screened for colon cancer.

The goal of treatment is to relieve symptoms.

Lifestyle changes can be helpful in some cases of IBS. For example, regular exercise and improved sleep habits may reduce anxiety and help relieve bowel symptoms.

Dietary changes can be helpful, but no specific diet can be recommended for IBS in general because the condition differs from one person to another. Increasing dietary fiber and avoiding items that stimulate the intestines such as caffeine may help.

Other possible treatments may include:

• Counseling in cases of severe anxiety or depression
• Antidiarrheal medications for those whose main symptom is diarrhea
• Low-dose antidepressants to help relieve intestinal pain
• Medications to stimulate bowel movements for those with constipation

Irritable bowel syndrome may be a life-long condition, but symptoms can often be improved or relieved through treatment.

• Dehydration
• Depression
• Discomfort
• Malnutrition resulting from avoiding food

Call your health care provider if you have symptoms of irritable bowel syndrome or if you notice a persistent change in your bowel habits.

Spiller R, Aziz Q, Creed F, Emmanuel A, et al. Guidelines on the irritable bowel syndrome: mechanisms and practical management. Gut. 2007 Dec;56(12):1770-98. Epub 2007 May 8.