Irritable Bowel Syndrome

Overview: What Is Irritable Bowel Syndrome?

Irritable bowel syndrome (IBS) is a disorder that affects the large intestine, or colon. Its symptoms include cramping, abdominal pain, bloating, constipation, and diarrhea. IBS is common, affecting up to 20 percent—one in five—of adults in the United States. More women suffer from IBS than men.

If you suffer from IBS, it may be reassuring to know that this disorder does not permanently damage the intestines. As well, IBS doesn’t lead to cancer and other serious diseases.

Causes of Irritable Bowel Syndrome

There is currently no known cause of IBS, but research indicates that it’s the result of sensitivity of the large intestine to certain foods and stress. This sensitivity may be the result irregular (too fast or too slow) muscle movement in colon (called motility), periodic spasms in motility, or temporary halts in motility.

Other potential factors in IBS include diminished serotonin (a neurotransmitter largely located in the gastrointestinal tract) receptor activity, the immune system, bacterial infection, and mild celiac disease (an inability to digest gluten).

Certain lifestyle factors, mostly related to diet, may make symptoms of IBS worse. These include:

  • Large meals
  • Caffeinated drinks such as coffee, tea, and cola
  • Alcohol
  • Foods such as wheat, rye, barley, chocolate, and milk products
  • Some medicines
  • Stress, conflict, emotional events, and anxiety

Symptoms of Irritable Bowel Syndrome

The main symptoms that characterize IBS are:

  • Bloating
  • Abdominal pain
  • Abdominal discomfort

Symptoms of IBS tend to vary from person to person as well as in frequency. In addition to the main symptoms described above, you may experience constipation or diarrhea or alternate between the two. Bowel movements may also change in appearance. In some cases symptoms come and go, while in others they remain constant.

Symptoms of Other Problems

When symptoms of IBS are accompanied by the following complaints, there is a risk for medical problems other than IBS: bleeding, fever, weight loss, or persistent severe pain.


If you think you have symptoms of IBS, see your doctor for a diagnosis. Be prepared to share your complete medical history and to describe your symptoms. There is no test for IBS, but you may be tested to rule out other conditions.

If your doctor rules out other conditions and confirms that symptoms indicating IBS are present, he or she may make a diagnosis of IBS. To diagnose IBS many doctors look for symptoms (abdominal pain and discomfort) that have been present for at least 12 weeks during the previous year and share two of these three features: 1) pain is relieved by having a bowel movement; 2) when pain is present, frequency of bowel movements change; 3) when pain is present, the form and appearance of stool changes.

What are the four types of IBS?

Doctors classify IBS into one of four types based on “usual stool consistency. These types are important because they determine the types of treatment that are most likely to improve your symptoms.

The four types of IBS are

  • IBS-C with constipation:
    • hard or lumpy stools at least 25 percent of the time
    • loose or watery stools less than 25 percent of the time
  • IBS-D with diarrhea:
    • loose or watery stools at least 25 percent of the time
    • hard or lumpy stools less than 25 percent of the time
  • Mixed IBS-M, experience both diarrhea and constipation:
    • hard or lumpy stools at least 25 percent of the time
    • loose or watery stools at least 25 percent of the time
  • Unsubtyped IBS-U
    • hard or lumpy stools less than 25 percent of the time
    • loose or watery stools less than 25 percent of the time


There isn’t currently a cure for IBS, but with a combination of medical treatment and diet and lifestyle adjustments, symptoms can be managed.


Because IBS is often made worse by stress, taking steps to manage stress in your life may help relieve symptoms. Some people find that relaxation techniques including breathing exercises, meditation, and yoga help reduce stress. As well, physical activity and adequate sleep can help control stress, as can any activity that you find calming—reading, listening to music, taking a walk with a friend, for example. Counseling and support from counselors, friends, family, and support groups can also help manage stress and help you find ways to avoid or navigate stressful situations.


Keep track of the foods that seem to trigger symptoms of IBS. Some people find that a written record, or food journal, helps them identify problem foods. Record details such as what you eat, time of day, and how much and how you feel afterward. By avoiding foods that seem to cause discomfort, you may be able to reduce symptoms. For additional help making changes to your diet, you may wish to consult a registered dietician.

Some dietary tips that may help relieve symptoms include:

  • Drink plenty of water and avoid carbonated beverages, which may cause gas.
  • Don’t chew gum or eat too quickly; these behaviors can cause you to swallow air, which can cause gas.
  • Try eating smaller meals more frequently and avoid large meals.
  • Try increasing fiber in your diet gradually. Fiber can help reduce constipation, but it can also make gas and cramping worse. It’s therefore important to slowly increase the amount of fiber you consume.
  • Avoid foods and beverages that make your symptoms worse. For some people these include alcohol, drinks with caffeine, dairy products, beans, cauliflower, and broccoli.


Medication may be used to address symptoms of IBS. Even though some of these medications are available over the counter, it’s important to consult your doctor before taking them and to follow his or her directions. Medications include:

  • Fiber supplements or laxatives to relieve constipation
  • Medicines such as Lomotil® (diphenoxylate and atropine) or Imodium® (loperamide) to decrease diarrhea
  • Antispasmodics to reduce muscles spasms in the colon
  • Antidepressants to relieve some symptoms

There is a medication available specifically for the treatment of IBS: Lotronex® (alosetron hydrocholoride). Lotronex, however, is associated with serious side effects and is therefore used cautiously. It’s approved by the U.S. Food and Drug Administration for women with severe IBS who have not responded to conventional therapy and whose primary symptom is diarrhea.

Living with Irritable Bowel Syndrome

If IBS isn’t managed, symptoms may impact your overall quality of life. The condition may impact your social life by causing you to avoid making plans when you’re experiencing symptoms. Your sex life may also be affected, as IBS may make you too physically uncomfortable to enjoy intimacy. As well, IBS may affect you professional life—people with the condition tend to miss more workdays than people who don’t have IBS.

Fortunately, with proper management, you can live a full and active life if you have IBS. By following your doctor’s recommendations and finding medications and lifestyle and diet changes to help control symptoms, IBS can be a very manageable condition.


International Foundation for Functional Gastrointestinal Disorders

National Digestive Diseases Information Clearinghouse