Irritable Bowel Syndrome (IBS)


What Is It?

Irritable bowel syndrome (IBS) is a common but poorly understood disorder that causes a variety of symptoms including abdominal pain, diarrhea and/or constipation, bloating, gassiness and cramping. Because these symptoms may be caused by a number of different bowel diseases, IBS is usually diagnosed only after your doctor rules out the possibility of a more serious problem.

The severity of the disorder varies from person to person. Some people experience symptoms that come and go and are just mildly annoying, while others have such severe daily bowel problems that IBS affects their ability to work, sleep and enjoy life. In addition, symptoms may change over time. A person may have severe symptoms for 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 any other disease, and does not develop into any other disease, such as ulcerative colitis or colon cancer.

IBS usually starts in early adulthood. It affects twice as many women as men. Approximately 10 percent 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.

No one knows what causes IBS. Doctors cannot easily identify specific abnormalities of the bowel that produce the symptoms of IBS. Some studies suggest that the nerves of the colon may be much more sensitive than usual in people with IBS. The normal movement of food and gas through the colon causes greater than usual pain, intestinal spasms and an irregular pattern of bowel movements.

In the past, it was thought that stress might cause IBS. That is no longer the case. Stress does not cause IBS, but stress can increase the symptoms, especially pain.

IBS has been called irritable colon, spastic colon, mucous colitis and functional bowel disease.


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

  • Mild or severe abdominal pain, discomfort or cramping, usually relieved after a bowel movement
  • 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
  • In extreme cases, nausea, dizziness or fainting

Although the symptoms of IBS often change over time, people tend to develop their own particular pattern, such as mostly diarrhea, mostly constipation, or abdominal pain without a major change in bowel movements.


No single test — or even a battery of tests — can offer a definite diagnosis of IBS because there are no measurable physical changes that occur with the syndrome. Instead, doctors usually make this diagnosis when a person has the typical symptoms, and other disorders that can cause similar symptoms have been ruled out.

Your doctor will ask you questions about your medical history and symptoms to determine if your symptoms match those typical for IBS. Your doctor will examine you, testing your abdomen for tenderness, feeling to determine whether internal organs are larger than normal. The doctor will check for fever or weight loss. If you have any of these signs, you may have something other than IBS.

Depending on your medical history, your doctor may do tests to eliminate other diseases that may cause similar symptoms. These tests might include:

  • Blood tests
  • Stool sample, to check for blood or evidence of infection
  • Sigmoidoscopy, in which a flexible, lighted tube with a tiny camera on the end is inserted into the rectum and up the left side of the colon, or a colonoscopy, in which a longer tube examines the entire colon to look for internal abnormalities
  • Barium X-ray, in which a chalky solution is swallowed or pumped into the rectum to coat the inside of the gastrointestinal tract and highlight abnormalities
  • Asking you to stop eating or drinking certain foods for up to three weeks to determine if your diet is contributing to your symptoms (for example, lactose intolerance)

Expected Duration

IBS symptoms may be a daily problem throughout a person’s life or symptoms may occur sporadically and last a day, a week or a month before disappearing. Treatment may get rid of symptoms, and dietary changes may help to reduce the frequency or severity of symptoms.


Because no one knows what causes IBS, it is impossible to prevent the disorder. Once diagnosed with IBS, a person may be able to reduce the frequency and severity of symptoms by reducing stress or changing the diet.


One of the easiest ways to treat IBS is to change your diet to reduce the likelihood that an IBS attack will occur.

Everybody has different “trigger” foods that tend to create IBS symptoms. Doctors recommend monitoring what you eat so you can find out what you ate before an attack. After you discover your particular trigger foods, eliminate them from your diet. Some common IBS trigger foods include:

  • Cabbage, broccoli, kale, legumes and other gas producing foods
  • Caffeine
  • Alcohol
  • Dairy products
  • Fatty foods, including whole milk, cream, cheese, butter, oils, meats and avocados
  • Raw fruits
  • Foods, gums and beverages that contain sorbitol, an artificial sweetener

The way you eat may help to create IBS symptoms. Eating large meals can cause cramping and diarrhea, so eating smaller meals more often may help some people with IBS. Eating quickly can cause you to swallow air, which can cause belching or gas.

Adding fiber to your diet, especially if constipation is one of your main symptoms, can help to loosen stools and reduce abdominal pain. At first, fiber will increase the amount of gas in your system, so add fiber gradually. Over time, the body adjusts to the effects of fiber and the gassiness will decrease. Fruits, vegetables and whole grain breads and cereals are good food sources of fiber. Your doctor may recommend a fiber supplement. The fiber methylcellulose creates the least amount of gas, and often is recommended for people with IBS. Psyllium is also a good source of fiber, but may create more gassiness at first.

If your symptoms are not relieved after you eliminate trigger foods and add fiber, your doctor may prescribe medications. Depending on what your most difficult symptoms are, medications can include:

  • Antidiarrheals — loperamide (Imodium), diphenoxylate (Lomotil and other brand names)
  • Antispasmodics to reduce cramping — dicyclomine (Bentyl)
  • Pain reducing agents — amitriptyline (Elavil), desipramine (Norpramin)
  • Antianxiety medication to help reduce stress that may be contributing to symptoms — lorazepam (Ativan)

In addition, two other prescription medications are available for women with symptoms that do not respond to other therapies. Both drugs target a branch of the nervous system in the gastrointestinal tract that may be active only in women.

Two other prescription medications are available for women with symptoms that do not respond to other therapies. Both drugs target a branch of the nervous system in the gastrointestinal tract that may be active only in women. Women with constipation related to IBS can take tegaserod (Zelnorm) for a limited time. (Women with a history of bowel obstruction, active gallstones, severe kidney or liver impairment, active diarrhea and bowel adhesions should not take Zelnorm. If abdominal cramps worsen with the medication, you should stop taking it immediately.) The other medication, alosetron (Lotronex), is limited to women with IBS in which severe diarrhea is the most common symptom. It requires enrollment in a special program because of rare cases of life threatening complications.

When To Call A Professional

See a doctor if you have blood in your stool, if abdominal pain is accompanied by vomiting, dizziness or fainting, if abdominal pain or diarrhea awakens you from sleep, or if you have unexplained weight loss or fever.


There is no cure for IBS, but symptoms can be managed with dietary changes, stress reduction and, if necessary, medication. Often, just knowing that the symptoms are not a sign of a major disease is enough to make people feel more at ease.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.