Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a condition of the large intestine. It can cause abdominal pain and changes in bowel habits. IBS can usually be treated with diet, stress management, and medicines.

Irritable Bowel Syndrome Overview

Reviewed: May 19, 2014

Irritable bowel syndrome (IBS) is a group of symptoms that affect the large intestine (colon) and include pain or discomfort in your abdomen and changes in your bowel movement patterns. IBS is a functional gastrointestinal (GI) disorder, meaning that it is a disorder in which the GI tract behaves in an abnormal way without evidence of damage due to a disease. Some people with the disorder have constipation and some have diarrhea. Others experience both diarrhea and constipation. Although IBS can cause a great deal of discomfort, it does not harm the intestines.

IBS is common. It is estimated to affect 10 to 15 percent of American adults, but only 5 to 7 percent of adults in the United States have received a diagnosis of IBS. Women are twice as likely as men to have IBS. It is most often found in people younger than 45 years. No one knows the exact cause of IBS. Some people can control their symptoms by managing diet, lifestyle, and stress, but others will need medication and counseling.

Irritable Bowel Syndrome Symptoms

The signs and symptoms of IBS can vary widely from person to person and often resemble those of other diseases. Only a small number of people with IBS have severe signs and symptoms.

The most common symptoms of IBS include pain or discomfort in your abdomen and changes in how often you have bowel movements or how your stools look. Other symptoms of IBS are:

  • a bloated feeling
  • gas
  • diarrhea or constipation — sometimes alternating bouts of constipation and diarrhea
  • mucus in the stool
  • the feeling that you have not finished a bowel movement

For most people, IBS is a chronic condition, although there will likely be times when the signs and symptoms are worse and times when they improve or even disappear completely.

Women with IBS often have more symptoms during their menstrual periods.

While IBS can be painful, IBS does not cause other health problems or damage your GI tract.

Irritable Bowel Syndrome Causes

The exact cause of IBS is unknown, but a variety of factors likely play a role. The walls of the intestines are lined with layers of muscle that contract and relax in a coordinated rhythm to move food from your stomach through your intestinal tract to your rectum. If you have IBS, the contractions may be stronger and last longer than normal, causing gas, bloating and diarrhea. Or the opposite may occur, with weak intestinal contractions slowing food passage and leading to hard, dry stools.

Abnormalities in your GI nervous system also may play a role, causing you to experience greater than normal discomfort when your abdomen stretches from gas or stool. Poorly coordinated signals between the brain and the intestines can make your body overreact to the changes that normally occur in the digestive process. This overreaction can cause pain, diarrhea or constipation.

Many factors can trigger symptoms in people with IBS, but not all people with the condition react to the same stimuli. Common triggers include:

  • foods allergies and sensitivities
  • stress
  • hormones
  • other illnesses or infections

IBS may also have a genetic cause. IBS is more common in people with family members who have a history of GI problems.

The link between mental health and IBS is unclear, but IBS is common in people with mental health problems such as panic disorder, anxiety, depression, and post-traumatic stress disorder.


Irritable Bowel Syndrome Diagnosis

There is no specific test for IBS. To diagnose IBS, your doctor will take a complete medical history and perform a physical exam.

The medical history will include questions about your symptoms, family history of GI disorders, recent infections, medicines you take, and stressful events related to the start of your symptoms. Your doctor may diagnose IBS if your symptoms started at least 6 months ago or if you have had pain or discomfort in your abdomen at least 3 times a month for the past 3 months. You may also be diagnosed with IBS if your abdominal pain or discomfort has 2 or 3 of the following features:

  • your pain or discomfort improves after a bowel movement
  • you notice a change in how often you have a bowel movement
  • you notice a change in the way your stools look

Your doctor may run tests to rule out other diseases that could be causing your symptoms. These tests may include stool sampling tests, blood tests, and x-rays. Your doctor may also do a test called a sigmoidoscopy or colonoscopy to look inside your large intestine.

Living With Irritable Bowel Syndrome

In many cases, simple changes in your diet and lifestyle can provide relief from symptoms of IBS. Although your body may not respond immediately to these changes, your goal is to find long-term, not temporary, solutions.

  • Adjust your fiber intake. Fiber helps reduce constipation, but it can also make gas and cramping worse. The best approach is to slowly increase the amount of fiber in your diet over a period of weeks. Examples of foods that contain fiber are whole grains, fruits, vegetables and beans. If your signs and symptoms remain the same or worse, tell your doctor. You may also want to talk to a dietitian. Limiting dietary fiber and taking a fiber supplement instead may cause less gas and bloating. If you take a fiber supplement, such as Metamucil or Citrucel, be sure to introduce it slowly and drink plenty of water every day to reduce gas, bloating and constipation. If you find that taking fiber helps your IBS, use it on a regular basis for best results.
  • Avoid trigger foods. Do not eat foods that make your symptoms worse. These may include alcohol, chocolate, caffeinated beverages such as coffee and sodas, medications that contain caffeine, dairy products, and sugar-free sweeteners such as sorbitol or mannitol. Foods that might make gas and bloating worse include beans, cabbage, cauliflower and broccoli. Fatty foods also may be a problem for some people. Chewing gum or drinking through a straw can lead to swallowing air, causing more gas.
  • Eat at regular times. Do not skip meals and try to eat about the same time each day to help regulate bowel function. If you have diarrhea, you may find that eating small, frequent meals makes you feel better. If you are constipated, eating larger amounts of high-fiber foods may help move food through your intestines.
  • Drink plenty of liquids. Try to drink plenty of fluids every day. Water is best. Alcohol and beverages that contain caffeine stimulate your intestines and can make diarrhea worse, and carbonated drinks can produce gas.
  • Exercise regularly. Exercise helps relieve depression and stress and stimulates normal contractions of your intestines.
  • Use anti-diarrheal medications and laxatives with caution. Anti-diarrheal medications, such as Imodium or Kaopectate, and laxatives can cause problems if they are not used correctly. Use the lowest dose that helps for the shortest amount of time.

Irritable Bowel Syndrome Treatments

The goal of IBS treatment is the relief of symptoms so that you can live as normally as possible. If your symptoms are moderate or severe, you may need more than lifestyle and diet changes to manage your IBS. Your doctor may suggest the following medications:

  • Fiber supplements. Fiber supplements, such as psyllium (Metamucil) or methylcellulose (Citrucel), may help control constipation. If fiber does not help symptoms, your doctor may prescribe an osmotic laxative such as milk of magnesia or polyethylene glycol.
  • Anti-diarrheal medications. Over-the-counter medications, such as loperamide (Imodium), can help control diarrhea. Bile acid binders, such as cholestyramine (Prevalite), colestipol (Colestid) or colesevelam (Welchol), may be effective for some people with IBS, but these can lead to bloating.
  • Anticholinergic and antispasmodic medications. These medications, such as hyoscyamine (Levsin) and dicyclomine (Bentyl), can help relieve painful bowel spasms. They are sometimes used for people who have bouts of diarrhea, but they can worsen constipation and can lead to other symptoms, such as difficulty urinating. They should also be used with caution among people with glaucoma.
  • Antidepressant medications. If you also experience pain or depression, your doctor may recommend a tricyclic antidepressant or a selective serotonin reuptake inhibitor (SSRI). These medications help relieve depression as well as inhibit the activity of neurons that control the intestines.
  • Antibiotics. Some people whose symptoms are due to an overgrowth of bacteria in their intestines may benefit from antibiotic treatment. Some people with symptoms of diarrhea have benefited from rifaximin (Xifaxan), but more research is needed.

Two medications are currently approved for specific cases of IBS:

  • Alosetron (Lotronex). Alosetron can only be prescribed by doctors enrolled in a special program and it is intended for severe cases of diarrhea-predominant IBS in women who have not responded to other treatments. Alosetron is not approved for use by men. This medication relaxes the colon and slows the movement of waste through the lower bowel.
  • Lubiprostone (Amitiza). Lubiprostine is approved for women age 18 and older who have IBS with constipation. Its effectiveness in men is not proved, nor its long-term safety. This medication works by increasing fluid secretion in your small intestine to help with the passage of stool.

Irritable Bowel Syndrome Other Treatments

Irritable Bowel Syndrome Prognosis