Irritable Bowel Syndrome (IBS)

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Irritable bowel syndrome (IBS) facts

  • Irritable bowel syndrome (IBS) is a type of gastrointestinal disorder. IBS symptoms and signs include
  • The exact cause of irritable bowel syndrome (IBS) is unknown and may be due to multiple factors.
  • A diagnosis of IBS is based on the duration (at least six months) and frequency of signs and symptoms (at least three times a month).
  • There is no known cure for IBS, but there are many treatment options to reduce or eliminate symptoms. Treatment includes dietary modifications, lifestyle changes, and prescription medications.
  • It is best to talk to a primary-care physician or a gastroenterologist about the best way to manage IBS symptoms and signs.

Irritable bowel syndrome (IBS) definition

Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by the presence of a cluster of symptoms and signs that include cramping, abdominal pain, increased gas, altered bowel habits, food intolerance, and bloating (distention).

Irritable bowel syndrome is a "functional" disorder. This term refers to the changes in the functioning of the digestive system that results in the collection of symptoms referred to as IBS, meaning that it is a problem with the movement (motility) rather than any damage to the tissues of the digestive system.

In the past, irritable bowel syndrome was also called spastic colon or bowel, functional bowel disease, mucous colitis, or nervous colon. IBS is not the same as colitis, which is a group of separate conditions also referred to as inflammatory bowel disease (IBD).

What causes irritable bowel syndrome (IBS)?

The exact cause of irritable bowel syndrome (IBS) is unknown. It is believed to be due to a number of factors including alteration in the gastrointestinal (GI) tract motility, abnormal nervous system signals, increased sensitivity to pain, and food intolerances. The following are some risk factors believed to cause IBS:

  • Abnormal movements of the colon and small intestines (too fast or slow, or too strong)
  • Hypersensitivity to pain from a full bowel or gas
  • Food sensitivities, possibly caused by poor absorption of sugars or acids in food
  • Gastroenteritis, a viral or bacterial infection of the stomach and intestines, may trigger IBS symptoms
  • Psychological conditions such as anxiety or depression are observed in many people with IBS, though they have not been found to be a direct cause of IBS.
  • Reproductive hormones or neurotransmitters may be off-balance in people with IBS.
  • Small intestinal bacterial overgrowth (SIBO)
  • Genetics is thought to be a possible cause of IBS, but so far this hereditary link has not been proven.
Medically Reviewed by a Doctor on 3/20/2015

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Read about IBS symptoms and signs.

Irritable Bowel Syndrome (IBS) Symptoms and Signs

The main symptoms of IBS are

  • abdominal pain or discomfort,
  • a change in bowel habits.

Other symptoms sometimes seen with IBS include

  • bloating,
  • passing mucus along with stools,
  • a sense that their bowel movements are not complete,
  • flatulence (passing gas).