Irritable Bowel Syndrome
(IBS · Functional Bowel Disorder · Spastic Bowel · Spastic Colon)
In this condition factsheet:
The Facts on Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is a common disorder of the intestine, causing abdominal pain with constipation, diarrhea, or alternating periods of both. IBS is also known as spastic colon or spastic bowel (terms that have fallen out of favour now) and functional bowel disorder. It's sometimes mistaken for colitis, an inflammatory bowel disease that is actually a more serious condition involving damage to the colon. IBS doesn't do any damage to the colon.
IBS affects about 10% to 20% of the population and is second only to the common cold as the most frequent cause of days lost to work and school. IBS symptoms can disappear for periods of time and then return. They usually start in the late teens or early 20s.
Unlike inflammatory bowel disease (ulcerative colitis and Crohn's disease), IBS brings no extra risk of cancer of the colon. However, if symptoms of IBS begin in people over age 50, it's best to rule out polyps and colon cancer by having a direct inspection of the lower bowel done by a doctor.
Causes of Irritable Bowel Syndrome
The cause of IBS isn't known, but it's currently thought to be due to the large and small intestines over- or under-sensing factors that may lead to abnormal bowel function. It is also thought to be influenced by psychological and social factors. For people with IBS, some situations may trigger pain and discomfort:
- emotional stress
- eating
- excessive gas
- female hormones (for menstruating people with IBS, symptoms often worsen during periods)
- certain medications and food (e.g., alcohol, chocolate, coffee, dairy products, fatty foods, fructose, carbohydrates)
- sometimes IBS develops after a bout of gastroenteritis
- for some people, an overgrowth of bacteria in the small intestine can lead to IBS
Symptoms and Complications of Irritable Bowel Syndrome
Symptoms of IBS include:
- abdominal pain and cramps, which may come in "on-again, off-again" bouts or as a continuous dull ache
- constipation or diarrhea, or alternating periods of both
- urgent need to have a bowel movement
- excessive gas
- bloating
- changes in bowel habits
- mucus in the stool
Blood in the stool is never a symptom of IBS. People who have blood in their stool, constant pain, vomiting, weight loss, or who have a fever should see a doctor. For other possible causes of these symptoms, refer to our disease articles on Crohn's disease, ulcerative colitis, and hemorrhoids.
