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Irritable Bowel Syndrome (IBS)

What is IBS?

Irritable bowel syndrome (IBS) is a disorder that affects your large intestine or colon. It causes:

  • Belly or abdominal cramps
  • Gas
  • Swelling or bloating
  • Changes in your bowel habits, such as diarrhea or constipation

When you have IBS your colon looks normal. But it does not work the way it should.

Health experts have not been able to find an exact physical cause for IBS. It is often thought that stress is one cause. Stress may make IBS symptoms worse.

IBS is a long-term, chronic condition. It can be painful. But it doesn’t cause lasting harm to your intestines. And it doesn’t lead to serious disease such as cancer.

There is no link between IBS and Crohn's disease, ulcerative colitis, or other inflammatory bowel diseases.

What causes IBS?

The exact cause of IBS isn’t known. Some experts think that if you have IBS your colon may be more sensitive than normal. That means it has a strong reaction to things that should not normally affect it.

When you have IBS, your colon muscles begin to move and tighten uncontrollably (spasm) after only mild stimulation or after normal events such as:

  • Eating
  • Swelling or bloating from gas or other material in the colon
  • Some medicines
  • Some foods

Women with IBS seem to have more symptoms during their periods. This could mean that the chemicals (reproductive hormones) released during a woman’s menstrual cycle may increase IBS symptoms.

Some things can make IBS symptoms worse. The 2 things most likely to make your IBS symptoms worse are the foods you eat and having emotional stress.

  • Diet. Eating makes your colon muscles move or contract. This normally gives you an urge to have a bowel movement 30 to 60 minutes after a meal. Having fat in your diet can cause contractions in your colon after a meal. With IBS the urge may come sooner. You will also have cramps or diarrhea.
  • Stress. If you have IBS, stress can make your colon move uncontrollably or spasm. Experts don’t fully understand why. But they believe this happens because the colon is partly controlled by the brain and spinal cord (nervous system). The nervous system controls how your body moves and reacts to things. Going for counseling or therapy and trying to reduce your stress can help to ease IBS symptoms. But this doesn’t mean that IBS is caused by a mental or emotional disorder. IBS is caused in part because of a problem with how the muscles of the colon move.

Who is at risk for IBS?

You are more likely to be at risk for IBS if you:

  • Are young. Most people first get IBS before they are 45 years old.
  • Are a woman. Women get IBS almost twice as much as men.

What are the symptoms of IBS?

Each person’s symptoms may vary. Some of the most common symptoms include:

  • Having belly or abdominal pain
  • Having painful constipation or diarrhea
  • Going back and forth between having constipation and having diarrhea
  • Having mucus in your stool

The symptoms of IBS may look like other health problems. Always see your doctor to be sure.

How is IBS diagnosed?

Your health care provider will look at your past health and give you a physical exam. He or she will also do lab tests to check for infection and for redness and swelling (inflammation).

There are usually no physical signs to tell for sure that you have IBS. There is also no exact test for IBS.

Your health care provider will do lab tests and imaging tests to make sure that you don’t have other diseases. These tests may include the following:

  • Blood tests. These are done to see if you are lacking healthy red blood cells (anemia), have an infection, or have an illness caused by inflammation or irritation.
  • Urinalysis and urine culture.These help to see if you have an infection in any part of your urinary system (urinary tract infection or UTI). This includes your kidneys, the tubes that send urine from the kidneys to the bladder (ureters), your bladder, and the urethra, where urine leaves your body.
  • Stool culture. This test checks for any abnormal bacteria in your digestive tract that may cause diarrhea and other problems. To do this, a small stool sample is taken and sent to a lab.
  • Stool testing for blood (fecal occult blood test). This test checks for hidden (occult) blood in your stool that can only be seen with a microscope. A small amount of stool is put on a special card. This is then tested in your health care provider’s office or sent to a lab. If blood is found, it may mean you have redness and swelling (inflammation) in your GI (gastrointestinal) tract.
  • Upper endoscopy, also called EGD (esophagogastroduodenoscopy). This test looks at  the inside or lining of your food pipe (esophagus), stomach, and the top part of your small intestine (duodenum). This test uses a thin, lighted tube, called an endoscope. The tube has a camera at one end. The tube is put into your mouth and throat. Then it goes into your esophagus, stomach, and duodenum. Your health care provider can see the inside of these organs. He or she can also take a small tissue sample (biopsy) if needed.
  • Abdominal X-rays. This test makes images of your internal tissues, bones, and organs.
  • Abdominal ultrasound. This test shows your internal organs as they work. It checks how blood is flowing through different blood vessels.
  • Colonoscopy. This test looks at the full length of your large intestine. It can help check for any abnormal growths, red or swollen tissue (inflammation), sores (ulcers), or bleeding. A long, flexible, lighted tube called a colonoscope is put into your rectum up into the colon. This tube lets your health care provider see the lining of your colon and take out a tissue sample (biopsy) to test it. He or she may also be able to treat some problems that may be found.

How is IBS treated?

Your health care provider will create a care plan for you based on:

  • Your age, overall health, and past health
  • How serious your case is
  • How well you handle certain medicines, treatments, or therapies
  • If your condition is expected to get worse
  • What you would like to do

Treatment for IBS may include:

  • Changes in your diet. Eating a proper diet is important if you have IBS. In some cases a high-fiber diet can reduce symptoms. Keep a list of foods that cause you pain, and talk about this with your health care provider.
  • Medicines. Your health care provider may prescribe fiber supplements or have you take something now and then to loosen your stool (a laxative). Other options may include medicines that ease nausea and vomiting (serotonin antagonists), stop muscle spasms (antispasmodic medicines), make you calm (tranquilizers), or help ease symptoms of depression (antidepressants).

Good fiber sources may include:



Moderate fiber

High fiber


Whole wheat bread, granola bread, wheat bran muffins, Nutri-Grain waffles, popcorn



Bran Flakes, Raisin Bran, Shredded Wheat, Frosted Mini Wheats, oatmeal, Mueslix, granola, oat bran

All-Bran, Bran Buds, Corn Bran, Fiber One, 100% Bran


Beets, broccoli, Brussels sprouts, cabbage, carrots, corn, green beans, green peas, acorn and butternut squash, spinach, potato with skin, avocado



Apples with peel, dates, papayas, mangos, nectarines, oranges, pears, kiwis, strawberries, applesauce, raspberries, blackberries, raisins

Cooked prunes, dried figs

Meat substitutes

Peanut butter, nuts

Baked beans, black-eyed peas, garbanzo beans, lima beans, pinto beans, kidney beans, chili with beans, trail mix

What are the complications of IBS?

The diarrhea and constipation that occur with IBS can cause hemorrhoids. If you already have hemorrhoids, they may get worse.

Your quality of life may be affected by IBS, because the symptoms may limit your daily activities.

What can I do to prevent IBS?

Health experts don’t know what causes IBS. They also don’t know how to stop it from happening.

Living with IBS

IBS symptoms can affect your daily activities. It’s important to work with your health care provider to manage the disease. You may need a plan to deal with issues such as diet, work, lifestyle, and emotional or mental health.

When should I call my health care provider?

Call your health care provider right away if your symptoms get worse or if you have new symptoms.

Key points about IBS

  • IBS is a disorder that affects your large intestine or colon.
  • It is a long-term, chronic disorder.
  • The exact cause of IBS is not known.
  • When you have IBS your colon looks normal. But it does not work the way it should.
  • The things most likely to cause IBS are diet and emotional stress.
  • Treatment may include changing your diet and taking medicines.


Next steps

Tips to help you get the most from a visit to your health care provider:
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.
Online Medical Reviewer: Berry, Judith, PhD, APRN
Online Medical Reviewer: Holloway, Beth, RN, M.Ed.
Online Medical Reviewer: Weisbart, Ed, M.D.
Date Last Reviewed: 10/29/2013
© 2000-2015 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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