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Irritable bowel syndrome

  • Alternative Names

    Spastic colon; Irritable colon; Mucous colitis; Spastic colitis


    Symptoms range from mild to severe. Most people have mild symptoms. Symptoms vary from person to person.

    Abdominal pain, fullness, gas, and bloating that have been present for at least 6 months are the main symptoms of IBS. The pain and other symptoms will often:

    • Occur after meals
    • Come and go
    • Be reduced or go away after a bowel movement

    People with IBS may switch between constipation and diarrhea, or mostly have one or the other.

    • People with diarrhea will have frequent, loose, watery stools. They will often have an urgent need to have a bowel movement, which is difficult to control.
    • Those with constipation will have difficulty passing stool, as well as less frequent bowel movements. They will often need to strain and will feel cramping with a bowel movement. Often, they do not eliminate any stool, or only a small amount.

    For some people, the symptoms may get worse for a few weeks or a month, and then decrease for a while. For other people, symptoms are present most of the time and may even slowly increase.

    People with IBS may also lose their appetite.

    Signs and tests

    Most of the time, your doctor can diagnose IBS based on your symptoms, with few or no tests. Eating a lactose-free diet for 2 weeks may help the doctor evaluate for a possible lactase deficiency.

    There is no test to diagnose IBS, but tests may be done to rule out other problems:

    • Blood tests to see if you have a low blood count (anemia)
    • Stool cultures to rule out an infection

    Some patients will have sigmoidoscopy or colonoscopy. During these tests, a hollow tube is inserted through the anus. The doctor can see through this tube. You may need these tests if:

    • Symptoms began later in life (over age 50)
    • You have symptoms such as weight loss or bloody stools
    • You have abnormal blood tests (such as a low blood count)

    Other disorders that can cause similar symptoms include:

    • Celiac disease
    • Colon cancer (although cancer rarely causes typical IBS symptoms, unless symptoms such as weight loss, blood in the stools or abnormal blood tests are present)
    • Crohn's disease or ulcerative colitis