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What Is IBS?

People who have irritable bowel syndrome (IBS) have digestive tracts that react abnormally to certain substances or to stress. This leads to symptoms like cramps, gas, bloating, pain, constipation, and diarrhea. Sometimes called “spastic colon,” IBS is a common condition that is not a disease, but rather a group of symptoms that occur together.

Outline of human figure showing digestive system. Stomach breaks down food. Small intestine absorbs nutrients and passes waste on to colon. Colon (large intestine) absorbs water from waste and moves it out of body. Rectum is where waste is stored before it passes out of body.
Muscle contraction moves food through the digestive tract.

IBS—a motility problem

The muscle movement that passes food through the digestive tract is called motility. When you have IBS, the normal motility of the digestive tract (especially the colon) is disrupted. Motility may speed up, slow down, or become irregular. If stool passes too quickly through the colon, not enough water is absorbed from it. Loose, watery stools (diarrhea) can result. If stool passes through the colon too slowly, too much water is absorbed and the stool becomes hard and dry (constipation). Also, stool and gas may back up and cause painful pressure and cramping.

What causes IBS?

  • Smoking, eating certain foods, or drinking alcohol or caffeinated drinks can cause symptoms of IBS.

  • Stress or anxiety can contribute to the motility problems that cause IBS.

  • Although no one knows for sure, IBS may be caused by a problem with the nerves or muscles in your digestive tract.

  • There is also some evidence that certain bacteria in the small intestine and colon may cause IBS.

What you can do

  • Certain medications may help regulate the working of your digestive tract. Your health care provider may prescribe one or more for you.

  • Medication can’t cure IBS, but it may help manage the symptoms.

  • Because some medications may make IBS worse, don’t take any medication, especially laxatives, unless your health care provider prescribes it for you.

  • Your health care provider may suggest some lifestyle changes to help control your IBS. Two of the most important are changing your diet and managing stress.

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