Irritable Bowel Syndrome (IBS)


What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a chronic (ongoing) problem with the large intestine. IBS is not a disease. It is a term used to describe a group of symptoms that typically happen together. Common IBS symptoms include abdominal pain, bloating, and diarrhea or constipation, or a combination of both diarrhea and constipation. IBS may cause physical discomfort and emotional distress, but it does not cause damage to the large intestine. It’s not the same as inflammatory bowel diseases like ulcerative colitis, which do damage the intestine.

IBS is very common and occurs more often in women. IBS also has been called functional bowel syndrome, irritable colon, spastic bowel, and spastic colon.


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What are the symptoms of IBS?

Common symptoms of IBS include:

Symptoms are different for each person. You may have some or even all of the symptoms listed above. Most people have mild symptoms, but some people have severe symptoms that affect their day-to-day lives.

  • Abdominal pain and cramping (this may go away after having a bowel movement)
  • Bloating and gas
  • Constipation
  • Diarrhea
  • Alternating between constipation and diarrhea
  • Feeling a strong urge to have a bowel movement
  • Feeling like you still need to have a bowel movement after you’ve already had one
  • Mucus in the stool

Causes & Risk Factors

What causes IBS?

Doctors describe IBS as a “functional gastrointestinal disorder.” This means that it is caused by changes in how the gastrointestinal (digestive) system works, but no one knows exactly what causes these changes to occur. Most doctors and researchers believe that IBS is caused by a combination of health problems. Possible health problems that may cause or worsen IBS include:

  • Problems with the nerve signals from your brain to your intestine
  • Problems with how your intestines push food through your system
  • Mental health problems, such as depression, anxiety, and panic disorders
  • An infection in your stomach or intestines
  • An overgrowth of bacteria in the intestines
  • Changes in hormone levels or other body chemicals
  • Undiagnosed food sensitivities or allergies

Diagnosis & Tests

How is IBS diagnosed?

There is no test that will tell your doctor whether you have irritable bowel syndrome (IBS). Instead, your doctor will make a diagnosis based on whether you have certain signs or symptoms. These signs and symptoms are called diagnostic criteria. For IBS, the most commonly used diagnostic criteria are called the Rome criteria.

Do my symptoms meet the Rome criteria?

Your doctor will tell you whether your symptoms suggest IBS. Before you meet with your doctor, keep a record of your symptoms and when they occur. Share the record with your doctor to help him or her determine whether your symptoms fit the criteria for IBS. The Rome criteria put emphasis on the pattern and onset of pain or discomfort, and then define subtypes based on whether constipation, diarrhea, or both are present.

In order for your doctor to diagnose IBS, according to the Rome criteria, you must have had:

You must also have had at least 2 of the following:

What are the different subtypes of IBS?

IBS symptoms are different for each person. If you meet the Rome criteria, your doctor may use your symptoms to further classify your IBS as one of the 4 following subtypes:

  • IBS with constipation (IBS-C)
    • hard or lumpy stools at least 25% of the time
    • loose or watery stools less than 25% of the time
  • IBS with diarrhea (IBS-D)
    • loose or watery stools at least 25% of the time
    • hard or lumpy stools less than 25% of the time
  • Mixed IBS (IBS-M)
    • hard or lumpy stools at least 25% of the time
    • loose or watery stools at least 25% of the time
  • Unsubtyped IBS (IBS-U)
    • hard or lumpy stools less than 25% of the time
    • loose or watery stools less than 25% of the time

These subtypes help your doctor determine what treatments are most likely to help relieve your symptoms.

  • Pain or discomfort that goes away after a bowel movement
  • Pain or discomfort that began when the consistency (appearance) of your stool changed; for example, you went from having normal stool to having loose or dry stool
  • Pain or discomfort that began when the frequency of your bowel movements changed; for example, you went from having 1 bowel movement every day to having 3 every day, or to only having 1 every few days.

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What changes can I make at home to help control my symptoms?

There is no cure for IBS. The best way to help control your symptoms is to:

  • Lead a healthy lifestyle: Eat a varied, healthy diet, and drink plenty of water. Try to eat 5 or 6 smaller meals each day, instead of 3 big meals. Exercise regularly and make sure you’re getting enough sleep.
  • Avoid foods that make your symptoms worse: You may notice that your symptoms get worse when you eat certain foods. Foods that may make IBS symptoms worse include caffeinated beverages (coffee, tea), carbonated beverages, milk products, alcohol, chocolate, certain fruits, and beans or cabbage (which can cause gas). To help you figure out if a certain food bothers you, keep a food journal. Record what you eat and whether you have any IBS symptoms. If you find a pattern, talk to your doctor about whether you should remove that food from your diet and how to find healthy substitutes.
  • Find ways to handle stress: Your symptoms may get worse when you’re under stress, such as when you travel, attend social events, or change your daily routine, Talk to your family doctor about ways to deal with stress, such as exercise, relaxation training, or meditation. He or she may have some suggestions or may refer you to someone who can give you some ideas. Your doctor may also suggest that you talk to a counselor about things that are bothering you.

Why may fiber be helpful?

Fiber can be helpful because it helps improve how the intestines work. There are 2 types of fiber:

Increase the fiber in your diet slowly. Some people feel bloated and have gas if they increase their fiber intake too quickly. Gas and bloating usually improve as you get used to eating more fiber. The best way to increase your fiber intake is eat a wide variety of high-fiber foods. For more information, read the handout, “Fiber: How to Increase the Amount in Your Diet.”

  • Soluble fiber helps both diarrhea and constipation. It dissolves in water and forms a gel-like material. Many foods, such as oat bran, apples, beans, and citrus fruits, contain soluble fiber. Psyllium, a natural vegetable fiber, also is a soluble fiber. You can buy psyllium supplements (some brand names: Fiberall, Metamucil, Perdiem) to drink, and you can add it to other foods.
  • Insoluble fiber helps constipation by moving material more quickly through your digestive system and adding bulk to your stool. Insoluble fiber is in whole grain breads, nuts, seeds, wheat bran, and many vegetables and fruits.

Can my doctor prescribe medicine for IBS?

If your symptoms are severe, your doctor may prescribe medicine to help you manage or lessen your symptoms. For example, if your main symptom is pain, your doctor may prescribe antispasmodic medicines such as hyoscyamine or dicyclomine to reduce cramping. Heating pads and hot baths can also be comforting. If diarrhea is a frequent problem, medicine such as loperamide (brand name: Imodium) may help. If constipation is a problem, your doctor may prescribe a laxative or a medicine called lubiprostone. Depending on your symptoms, your doctor may prescribe a tranquilizer or sedative, an antidepressant, or an antibiotic. Your doctor may also recommend a probiotic or fiber supplement.

Will IBS get worse over time?

No. While IBS will probably recur throughout your life, it won’t get worse. It doesn’t cause cancer or require surgery, and it won’t shorten your life.

What if IBS interferes with my daily activities?

IBS may have caused you to avoid doing certain things, like going out or going to work or school. While it may take some time for your efforts to pay off, you may find new freedom by following a plan that includes a healthy diet, learning new ways to deal with your stress, and avoiding foods that may make your symptoms worse.

Questions to Ask Your Doctor

  • What is a food diary and how will it help you diagnose irritable bowel syndrome.
  • Is IBS a sign of another health conditions?
  • Are there lifestyle changes I could make that will help IBS?
  • What medicines are available to treat IBS? Are there side effects?
  • What can I do to ease and cope with stress?
  • What are the possible causes of my IBS?

Other Organizations



  • International Foundation for Functional Gastrointestinal Disorders (IFFGD). About Irritable Bowel Syndrome. Accessed 08/16/12
  • The Merck Manual. Irritable Bowel Syndrome (IBS). Accessed 08/16/12
  • National Digestive Diseases Information Clearinghouse (NDDIC). Irritable Bowel Syndrome. Accessed 08/16/12

This content has been supported by Forest Laboratories Inc.