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Irritable bowel syndrome (IBS) is a disorder of the large and small intestines that causes abdominal pain or discomfort. The pain occurs along with constipation or diarrhea. Other common symptoms are bloating, passing mucus in the stools, or a sense that you have not completely emptied your bowels.

Many people with IBS have alternating periods of constipation and diarrhea, but often one problem is more common than the other. A given episode may be milder or more severe than the one before it, but the disorder itself does not become worse over time. Irritable bowel syndrome does not lead to more serious diseases, such as inflammatory bowel disease or cancer.

Irritable bowel syndrome is a functional bowel disorder. This means that the movement of the digestive tract is impaired but doctors can find no change in physical structure, such as inflammation or tumors. The symptoms of IBS are thought to be related to abnormal muscle contractions in any part of the intestines.

IBS is one of the most common intestinal disorders. Most people's symptoms are so mild that they never visit a doctor. However, some people can have symptoms that are quite troublesome, especially abdominal cramps, bloating, and diarrhea.

Irritable bowel syndrome is a long-term (chronic) but manageable condition. Active involvement in treatment is important to successfully manage the condition. Treatment is adapted to fit individual needs. Medication is reserved for treating symptoms that do not respond to changes in diet and lifestyle.


No specific test can be used to diagnose irritable bowel syndrome (IBS), so doctors use symptoms to help diagnose the condition.

An expert panel has outlined a list of symptoms common in IBS. Doctors often use these symptoms, known as the Rome criteria, to tell IBS apart from other intestinal problems. However, people who don't have all of these symptoms may still have IBS.

You are believed to have IBS if abdominal pain or discomfort is continuous or comes and goes for at least 12 weeks (need not be consecutive) during the past year, and two of the three following conditions occur:

  • Pain is relieved by having a bowel movement.
  • The frequency of bowel movements changes.
  • The stools' appearance or form changes.

Bowel movement patterns

In IBS, your pattern of bowel movements varies at least 25% of the time. Two or more of the following may happen:

  • Bowel movements may occur either more often (diarrhea) or less often (constipation) than usual, such as having more than 3 bowel movements a day or less than 3 per week.
  • Bowel movements may differ in size or consistency (may be hard and pelletlike, pencil-thin, or loose and watery).
  • The way stools pass changes. You may strain, feel an urgent need to have a bowel movement, or feel that you haven't completely passed a stool.
  • You may have bloating or a feeling of gas in the intestines.

Other intestinal symptoms

Some people may have lower abdominal pain with constipation that is sometimes followed by diarrhea. Other people have pain and mild constipation but no diarrhea.

Symptoms that are sometimes present include:

  • Intestinal gas.
  • Passage of mucus in the stools.
  • Nausea and vomiting.
  • Loss of appetite.
  • Indigestion or heartburn.
  • Burping.

Non-gastrointestinal symptoms

You may sometimes have other symptoms that don't affect the intestines, such as:

  • Anxiety or depression.
  • Fatigue.
  • Headache.
  • Unpleasant taste in the mouth.
  • Backache.
  • Sleeping problems (insomnia) not caused by symptoms of IBS.
  • Sexual problems, such as pain during sex or lowered sexual desire.
  • Heart palpitations (feeling like the heart skips a beat or is fluttering).
  • Urinary symptoms (frequent or urgent need to urinate, trouble starting the urine stream, trouble emptying the bladder).

Symptoms often occur after a meal, during stressful times, or during menstruation.

Who is affected by irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common intestinal disorders.1 Up to 20% of people have symptoms of IBS, such as abdominal pain and altered bowel habits, although less than half of them see a doctor for their symptoms.

Estimates in the Western world are that between 8% and 23% of adults have IBS.2 The disorder is more common in women than in men. In the United States, it is estimated to occur in 14% to 24% of women and 5% to 19% of men.3 The condition is common in India, Japan, and China.

The condition is less likely to develop for the first time in people over age 60.

Classification of irritable bowel syndrome (IBS)

Most people who have irritable bowel syndrome (IBS) have mild symptoms that usually don't disrupt their lives. They usually don't need to see a doctor, other than for reassurance that they do not have a more serious problem, such as cancer.

About 25% of people who have IBS have more bothersome symptoms that occasionally disrupt work, school, or other activities. Episodes may be related to stressful events or to eating a particular type of food. In these people, physical and emotional factors may affect their symptoms.

Only a few people (about 5%) with IBS have severe symptoms, such as abdominal pain that is much more severe than would be expected from stress, meals, or a physical problem. These people often are also anxious, depressed, or under a lot of stress, and they may have trouble acknowledging that stress-related factors may be contributing to their problem.

Sometimes people who have severe IBS symptoms visit many doctors, trying to find a physical cause for their symptoms and to find a cure. Some may believe that their doctors are overlooking a serious problem and may believe that they need more tests or treatments. This can be very frustrating. It is often helpful to get a second opinion, if possible from a doctor who specializes in treating functional bowel disorders.


Medication is not a first choice for treatment of irritable bowel syndrome (IBS). Many people are able to control their symptoms with home treatment.

The goal of drug treatment is to relieve your symptoms enough to prevent them from interfering with your daily activities, because it may not be possible to eliminate symptoms. Medications may be prescribed to treat moderate to severe pain, diarrhea, or constipation that does not respond to home treatment.

  • Antidepressant medications may improve IBS symptoms even in people who do not have depression, especially the medication class known as tricyclic antidepressants. Antianxiety medications may help people whose anxiety contributes to their IBS symptoms.

  • No single medication has been shown to be effective in relieving IBS over the long term.

Medication Choices

In most cases, the choice of medication is based on your most troublesome symptom. If constipation is the most bothersome symptom, using bulking agents and increasing dietary fiber may be helpful.

The following medications may be used to treat severe diarrhea that does not improve with home treatment:

Your doctor also may prescribe certain medications such as an anticholinergic (antispasmodic) to treat severe, painful abdominal cramping.

The following medications may be used if long-term (chronic) pain also occurs with anxiety or depression:

Several new medications are being studied to treat IBS. They are not yet available for use in the United States. One group of medications relaxes smooth muscle to reduce abdominal pain and bloating. These agents include darifenacin, pinaverium, and trimebutine. Pinaverium and trimebutine are available in Europe.

Another group of medications under review controls the way the brain chemical (neurotransmitter) serotonin affects the gastrointestinal tract. Tegaserod has been found to reduce abdominal pain and constipation.5

Alosetron (Lotronex), which also affects how the intestines use serotonin, had been approved to treat abdominal pain and diarrhea in women who have IBS. Alosetron has been pulled from the market because of serious side effects. Some people who took the medication experienced severe constipation or reduced blood flow to the large intestine (ischemic colitis). In a few cases, side effects led to surgery to correct the problem. Seven deaths may have been linked to the medication.

However, it is possible that alosetron may return to the market for limited use. An advisory panel of the U.S. Food and Drug Administration has recommended strictly controlled use of alosetron in women with the most severe diarrhea from IBS. Many people who took the medication without side effects say it helped make their condition bearable. Still, some experts say the benefits of the medication do not outweigh the risk of serious side effects.

If you were taking this medication, talk to your doctor about other treatments that may improve your symptoms.

What to Think About

So far, there is no evidence that any medication provides long-term relief of irritable bowel syndrome. Since few medications have proven consistently helpful and because all medications have side effects, medication should be used for specific symptoms that disrupt your normal daily activities.

If you also have another illness, such as depression, that triggers symptoms of irritable bowel syndrome, drug treatment for that illness may help for longer periods of time.

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