Irritable bowel syndrome (IBS) is a common but poorly understood disorder that causes a variety of bowel symptoms including abdominal pain, diarrhea and/or constipation, bloating, gassiness and cramping. While these symptoms may be caused by a number of different bowel diseases, IBS is usually diagnosed only after your doctor has ruled out the possibility of a more serious problem. The severity of the disorder varies from person to person. Some patients experience intermittent symptoms that are just mildly annoying, while others may have such severe daily bowel problems that IBS affects their ability to work, sleep and enjoy life. In addition, symptoms may change over time, such a that an individual may have severe symptoms for a several weeks and then feel well for months, or even years. Most people are never cured of IBS, but the disorder is not related to and does not progress to any other disease, such as ulcerative colitis or colon cancer.

IBS usually starts in early adulthood, and affects twice as many women as men. Approximately 10 to 20 percent of the population suffers from IBS, but at least half of all people with the condition never seek medical care for their symptoms. IBS also has been called irritable colon, spastic colon, mucous colitis and functional bowel disease.

No one knows what causes IBS. It has been called a functional illness because doctors cannot easily identify specific problems with the structure or function of the bowel that produce the symptoms of IBS. Some studies suggest that in people with IBS, the nerves and muscles of the colon may be hypersensitive. This means that normal movement of food and gas through the colon causes greater-than-usual pain, intestinal spasms and an irregular patter of bowel movements.

In the past, it was thought that stress might cause IBS, or that the symptoms were "all in the head" of the patient. That is no longer the case. Physicians understand that stress does not cause IBS, although it can sometimes worsen symptoms, increase the perception of pain or precipitate a bout.

Symptoms

People with IBS may have some or all of these symptoms:

• Abdominal pain, discomfort or cramping, usually relieved after a bowel movement. Pain can be mild or severe.
• Periods of diarrhea, constipation or alternating diarrhea and constipation.
• Bloating, gassiness, or a feeling of having a distended abdomen.
• Mucus in bowel movements.
• Feeling as though a bowel movement is incomplete, that you haven't had total evacuation.
• In extreme cases, nausea, dizziness or fainting along with the above symptoms.