What is irritable bowel IBS is often classified into four subtypes based on a person’s usual stool consistency. These subtypes syndrome (IBS)? are important because they affect the types of Irritable bowel syndrome is a functional treatment that are most likely to improve the gastrointestinal (GI) disorder, meaning it is a person’s symptoms. The four subtypes of IBS are problem caused by changes in how the GI tract IBS with constipation (IBS-C) works. People with a functional GI disorder have - hard or lumpy stools at least 25 per- frequent symptoms, but the GI tract does not cent of the time become damaged. IBS is not a disease; it is a - loose or watery stools less than 25 group of symptoms that occur together. The most percent of the time common symptoms of IBS are abdominal pain or IBS with diarrhea (IBS-D) discomfort, often reported as cramping, along with - loose or watery stools at least 25 diarrhea, constipation, or both. In the past, IBS was percent of the time called colitis, mucous colitis, spastic colon, - hard or lumpy stools less than 25 nervous colon, and spastic bowel. The name was percent of the time changed to reflect the understanding that the Mixed IBS (IBS-M) disorder has both physical and mental causes and - hard or lumpy stools at least 25 per- cent of the time is not a product of a person’s imagination. - loose or watery stools at least 25 IBS is diagnosed when a person has abdominal percent of the time pain or discomfort at least three times per month Unsubtyped IBS (IBS-U) for the last 3 months without other disease or - hard or lumpy stools less than 25 injury that could explain the pain. The pain or percent of the time discomfort of IBS may occur with a change in - loose or watery stools less than 25 stool frequency or consistency or may be relieved percent of the time by a bowel movement.
What is the GI tract? tract—consists of the large intestine and anus. The large intestine absorbs water and any remaining The GI tract is a series of hollow organs joined in a nutrients from partially digested food passed from long, twisting tube from the mouth to the anus. the small intestine. The large intestine then The movement of muscles in the GI tract, along changes waste from liquid to a solid matter called with the release of hormones and enzymes, allows stool. Stool passes from the colon to the rectum. for the digestion of food. Organs that make up the The rectum is located between the last part of the GI tract are the mouth, esophagus, stomach, small colon—called the sigmoid colon—and the anus. intestine, large intestine—which includes the The rectum stores stool prior to a bowel appendix, cecum, colon, and rectum—and anus. movement. During a bowel movement, stool The intestines are sometimes called the bowel. The moves from the rectum to the anus, the opening last part of the GI tract—called the lower GI through which stool leaves the body.
Transverse colon
Descending colon Ascending colon
Sigmoid colon Cecum
Anus Rectum
How common is IBS and What causes IBS? who is affected? The causes of IBS are not well understood. Researchers believe a combination of physical Irritable bowel syndrome is estimated to affect 3 to and mental health problems can lead to IBS. The 20 percent of the population, with most studies possible causes of IBS include the following: ranging from 10 to 15 percent.1 However, less than one-third of people with the condition see a health Brain-gut signal problems. Signals care provider for diagnosis.2 IBS affects about between the brain and nerves of the small twice as many women as men and is most often and large intestines, also called the gut, found in people younger than 45 years. control how the intestines work. Problems with brain-gut signals may cause IBS symptoms, such as changes in bowel What are the symptoms of habits and pain or discomfort. IBS? GI motor problems. Normal motility, or The symptoms of IBS include abdominal pain or movement, may not be present in the discomfort and changes in bowel habits. To meet colon of a person who has IBS. Slow motility can lead to constipation and fast the definition of IBS, the pain or discomfort should motility can lead to diarrhea. Spasms, or be associated with two of the following three sudden strong muscle contractions that symptoms: come and go, can cause abdominal pain. start with bowel movements that occur Some people with IBS also experience more or less often than usual hyperreactivity, which is an excessive increase in contractions of the bowel in start with stool that appears looser and response to stress or eating. more watery or harder and more lumpy than usual Hypersensitivity. People with IBS have a lower pain threshold to stretching of the improve with a bowel movement bowel caused by gas or stool compared
with people who do not have IBS. The Other symptoms of IBS may include brain may process pain signals from the diarrhea—having loose, watery stools bowel differently in people with IBS. three or more times a day and feeling Mental health problems. Mental health, urgency to have a bowel movement or psychological, problems such as panic constipation—having hard, dry stools; disorder, anxiety, depression, and post- three or fewer bowel movements in a traumatic stress disorder are common in week; or straining to have a bowel people with IBS. The link between these movement disorders and development of IBS is unclear. GI disorders, including IBS, are feeling that a bowel movement is often found in people who have reported incomplete past physical or sexual abuse. Researchers passing mucus, a clear liquid made by the believe people who have been abused tend intestines that coats and protects tissues in to express psychological stress through the GI tract physical symptoms. abdominal bloating Bacterial gastroenteritis. Some people who have bacterial gastroenteritis—an Symptoms may often occur after eating a meal. To infection or irritation of the stomach and meet the definition of IBS, symptoms must occur intestines caused by bacteria— develop at least 3 days a month. IBS. Researchers do not know why gastroenteritis leads to IBS in some people and not others, though psychological problems and abnormalities of the lining of the GI tract may be factors. Small intestinal bacterial overgrowth How is IBS diagnosed? (SIBO). Normally, few bacteria live in the small intestine. SIBO is an increase in the To diagnose IBS, a health care provider will number of bacteria or a change in the type conduct a physical exam and take a complete of bacteria in the small intestine. These medical history. The medical history will include bacteria can produce excess gas and may questions about symptoms, family history of GI also cause diarrhea and weight loss. Some disorders, recent infections, medications, and researchers believe that SIBO may lead to stressful events related to the onset of symptoms. IBS, and some studies have shown For IBS to be diagnosed, the symptoms must have antibiotics to be effective in treating IBS. started at least 6 months prior and must have However, the studies were weak and more occurred at least 3 days per month for the previous research is needed to show a link between SIBO and IBS. 3 months. Further testing is not usually needed, though the health care provider may do a blood Body chemicals. People with IBS have test to screen for other problems. Additional altered levels of neurotransmitters, which diagnostic tests may be needed based on the results are chemicals in the body that transmit of the screening blood test and for people who also nerve signals, and GI hormones, though have signs such as the role these chemicals play in developing IBS is unclear. Younger fever women with IBS often have more rectal bleeding symptoms during their menstrual periods. Post-menopausal women have fewer weight loss symptoms compared with women who are anemia—too few red blood cells in the still menstruating. These findings suggest body, which prevents the body from get- that reproductive hormones can worsen ting enough oxygen IBS problems. family history of colon cancer, irritable Genetics. Whether IBS has a genetic bowel disease—long-lasting disorders that cause, meaning it runs in families, is cause irritation and ulcers, or sores, in the unclear. Studies have shown that IBS is GI tract—or celiac disease—an immune more common in people with family disease in which people cannot tolerate members who have a history of GI gluten, a protein found in wheat, rye, and problems. However, the cause could be barley, because it will damage the lining environmental or the result of heightened of their small intestine and prevent awareness of GI symptoms. absorption of nutrients Food sensitivity. Many people with IBS report that certain foods and beverages Additional diagnostic tests may include a stool can cause symptoms, such as foods rich in test, lower GI series, and flexible sigmoidoscopy carbohydrates, spicy or fatty foods, coffee, or colonoscopy. Colonoscopy may also be and alcohol. However, people with food recommended for people who are older than 50 to sensitivity typically do not have clinical screen for colon cancer. signs of food allergy. Researchers have proposed that symptoms may result from Stool tests. A stool test is the analysis of a sample poor absorption of sugars or bile acids, of stool. The health care provider will give the which help break down fats and get rid of person a container for catching and storing the wastes in the body. stool. The sample is returned to the health care provider or a commercial facility and sent to a lab for analysis. The health care provider may also do a rectal exam, sometimes during the physical exam, to check for blood in the stool. Stool tests can show the presence of parasites or blood.
Lower GI series. A lower GI series is an x-ray The gastroenterologist may also perform a biopsy, exam that is used to look at the large intestine. The a procedure that involves taking a piece of test is performed at a hospital or outpatient center intestinal lining for examination with a by a radiologist—a doctor who specializes in microscope. You will not feel the biopsy. A medical imaging. The health care provider may pathologist—a doctor who specializes in give the person written bowel prep instructions to diagnosing diseases—examines the tissue in a lab. follow at home. The person may be asked to Cramping or bloating may occur during the first follow a clear liquid diet for 1 to 3 days before the hour after the test. Driving is not permitted for 24 procedure. A laxative or enema may be used hours after a colonoscopy to allow the sedative before the test. A laxative is medication that time to wear off. Before the appointment, a person loosens stool and increases bowel movements. An should make plans for a ride home. Full recovery enema involves flushing water or laxative into the is expected by the next day. anus using a special squirt bottle. For the test, the person will lie on a table while How is IBS treated? the radiologist inserts a flexible tube into the Though there is no cure for IBS, the symptoms person’s anus. The large intestine is filled with can be treated with a combination of the barium, making signs of problems with the large following: intestine that may be causing the person’s symptoms show up more clearly on x rays. changes in eating, diet, and nutrition For several days, traces of barium in the large medications intestine cause stools to be white or light colored. probiotics Enemas and repeated bowel movements may cause therapies for mental health problems anal soreness. A health care provider will provide specific instructions about eating and drinking after the test. Eating, Diet, and Nutrition Large meals can cause cramping and diarrhea, so Flexible sigmoidoscopy and colonoscopy. The eating smaller meals more often, or eating smaller tests are similar, but a colonoscopy is used to view portions, may help IBS symptoms. Eating meals the rectum and entire colon, while a flexible that are low in fat and high in carbohydrates, such sigmoidoscopy is used to view just the rectum and as pasta, rice, whole-grain breads and cereals, lower colon. These tests are performed at a fruits, and vegetables, may help. hospital or outpatient center by a Certain foods and drinks may cause IBS gastroenterologist—a doctor who specializes in symptoms in some people, such as digestive diseases. For both tests, a health care provider will give written bowel prep instructions foods high in fat to follow at home. The person may be asked to milk products follow a clear liquid diet for 1 to 3 days before either test. The night before the test, the person drinks with alcohol or caffeine may need to take a laxative. One or more enemas drinks with large amounts of artificial may also be required the night before and about 2 sweeteners, which are substances used in hours before the test. place of sugar
In most cases, light anesthesia, and possibly pain foods that may cause gas, such as beans and cabbage medication, helps people relax. For either test, the person will lie on a table while the People with IBS may want to limit or avoid these gastroenterologist inserts a flexible tube into the foods. Keeping a food diary is a good way to track anus. A small camera on the tube sends a video which foods cause symptoms so they can be image of the intestinal lining to a computer screen. excluded from or reduced in the diet. The test can show signs of problems in the lower GI tract. Dietary fiber may lessen constipation in people TCAs work in people with IBS by with IBS, but it may not help with lowering pain. reducing sensitivity to pain in the GI tract Fiber helps keep stool soft so it moves smoothly as well as normalizing GI motility and through the colon. The Academy of Nutrition and secretion. Dietetics recommends consuming 20 to 35 grams Lubiprostone (Amitiza). Lubiprostone is of fiber a day for adults.3 Fiber may cause gas and prescribed for people who have IBS-C. trigger symptoms in some people with IBS. The medication has been found to Increasing fiber intake by 2 to 3 grams per day improve symptoms of abdominal pain or may help reduce the risk of increased gas and discomfort, stool consistency, straining, bloating. and constipation severity.
The antibiotic rifaximin can reduce abdominal bloating by treating SIBO. But scientists are still Medications debating the use of antibiotics to treat IBS, and The health care provider will select medications more research is needed. based on the person’s symptoms. Fiber supplements. Fiber supplements Probiotics may be recommended to relieve consti- Probiotics are live microorganisms, usually pation when increasing dietary fiber is bacteria, that are similar to microorganisms ineffective. normally found in the GI tract. Studies have found Laxatives. Constipation can be treated that probiotics, specifically Bifidobacteria and with laxative medications. Laxatives work certain probiotic combinations, improve symptoms in different ways, and a health care of IBS when taken in large enough amounts. But provider can provide information about more research is needed. Probiotics can be found which type is best for each person. More in dietary supplements, such as capsules, tablets, information about different types of and powders, and in some foods, such as yogurt. A laxatives can be found in the National health care provider can give information about the Digestive Diseases Information Clear- right kind and right amount of probiotics to take to inghouse (NDDIC) fact sheet Constipa- tion at www.digestive.niddk.nih.gov. improve IBS symptoms. More information about probiotics can be found in the National Center for Antidiarrheals. Loperamide has been Complementary and Alternative Medicine fact found to reduce diarrhea in people with sheet An Introduction to Probiotics at www.nccam. IBS, though it does not reduce pain, nih.gov/health/probiotics/introduction.htm. bloating, or other symptoms. Loperamide reduces stool frequency and improves Therapies for Mental Health stool consistency by slowing the movement of stool through the colon. Problems The following therapies can help improve IBS Antispasmodics. Antispasmodics, such as hyoscine, cimetropium, and pinaverium, symptoms due to mental health problems: help to control colon muscle spasms and Talk therapy. Talking with a therapist reduce abdominal pain. may reduce stress and improve IBS Antidepressants. Tricyclic antidepres- symptoms. Two types of talk therapy used sants (TCAs) and selective serotonin to treat IBS are cognitive behavioral reuptake inhibitors (SSRIs) in low doses therapy and psychodynamic, or can help relieve IBS symptoms including interpersonal, therapy. Cognitive abdominal pain. In theory, TCAs should behavioral therapy focuses on the person’s be better for people with IBS-D and SSRIs thoughts and actions. Psychodynamic should be better for people with IBS-C therapy focuses on how emotions affect due to the effect on colon transit, but this IBS symptoms. This type of therapy often has not been confirmed in clinical studies. involves relaxation and stress somatoform disorders—chronic pain or management techniques. other symptoms with no physical cause that are thought to be due to psychological Hypnotherapy. In hypnotherapy, the problems therapist uses hypnosis to help the person relax into a trancelike state. This type of How does stress affect IBS? therapy may help the person relax the muscles in the colon. Stress can stimulate colon spasms in people with IBS. The colon has many nerves that connect it to Mindfulness training. People practicing the brain. These nerves control the normal this type of meditation are taught to focus contractions of the colon and cause abdominal their attention on sensations occurring at discomfort at stressful times. In people with IBS, the moment and to avoid worrying about the meaning of those sensations, also the colon can be overly responsive to even slight called catastrophizing. conflict or stress. Stress makes the mind more aware of the sensations that arise in the colon. IBS symptoms can also increase a person’s stress level. What other conditions are Some options for managing stress include associated with IBS? participating in stress reduction and People with IBS often suffer from other GI and relaxation therapies such as meditation non-GI conditions. GI conditions such as getting counseling and support gastroesophageal reflux disease (GERD) and dyspepsia are more common in people with IBS taking part in regular exercise such as than the general population. GERD is a condition walking or yoga in which stomach contents flow back up into the minimizing stressful life situations as esophagus— the organ that connects the mouth to much as possible the stomach—because the muscle between the getting enough sleep esophagus and the stomach is weak or relaxes when it should not. Dyspepsia, or indigestion, is upper abdominal discomfort that often occurs after Points to Remember eating. Dyspepsia may be accompanied by fullness, bloating, nausea, or other GI symptoms. Irritable bowel syndrome (IBS) is a functional More information about these conditions can be gastrointestinal (GI) disorder, meaning it is a found in the NDDIC fact sheets Heartburn, problem caused by changes in how the GI tract Gastroesophageal Reflux (GER), and works. People with a functional GI disorder have Gastroesophageal Reflux Disease (GERD) and frequent symptoms, but the GI tract does not Indigestion at www.digestive.niddk.nih.gov. become damaged. IBS is not a disease; it is a group of Non-GI conditions often found in people with symptoms that occur together. IBS include IBS is estimated to affect 3 to 20 percent chronic fatigue syndrome—a disorder that of the population, with most studies causes extreme fatigue, which is tiredness ranging from 10 to 15 percent. However, that lasts a long time and limits a person’s less than one-third of people with the ability to do ordinary daily activities condition see a health care provider for diagnosis. chronic pelvic pain The symptoms of IBS include abdominal temporomandibular joint disorders— pain or discomfort and changes in bowel problems or symptoms of the chewing habits. Other symptoms of IBS may muscles and joints that connect the lower include jaw to the skull o diarrhea depression o constipation anxiety o feeling that a bowel movement is Safety Study of Probiotics in Adults with Irritable incomplete Bowel Syndrome, funded under NIH clinical trial o passing mucus number NCT00971711, is a phase I study of the o abdominal bloating safety and effectiveness of VSL#3 in adults with IBS. VSL#3 is a high-potency probiotic medical The causes of IBS are not well under- food that is commercially available. stood. Researchers believe a combination Acupuncture/Moxibustion for Irritable Bowel of physical and mental health problems Syndrome (Acu/ MoxalIBS), funded under NIH can lead to IBS. clinical trial number NCT00945074, tests the To diagnose IBS, a health care provider efficacy of acupuncture in combination with will conduct a physical exam and take a moxibustion for symptom improvement in adults complete medical history. The medical with IBS. Moxibustion is the application of heat history will include questions about from a burning herb at the acupuncture point. All symptoms, family history of GI disorders, participants will receive moxibustion and will be recent infections, medications, and assigned to one of three treatment protocols: stressful events related to the onset of standard acupuncture, individualized acupuncture, symptoms. and sham acupuncture.
Though there is no cure for IBS, the Participants in clinical trials can play a more active symptoms can be treated with a combi- role in their own health care, gain access to new nation of the following: research treatments before they are widely available, and help others by contributing to o changes in eating, diet, and medical research. For information about current nutrition studies, visit www.ClinicalTrials.gov. o medications o probiotics Acknowledgments o therapies for mental health Publications produced by the Clearinghouse are problems carefully reviewed by both NIDDK scientists and outside experts. This publication was reviewed by William E. Whitehead, Ph.D., University of North Hope through Research Carolina Center for Functional GI and Motility The National Institute of Diabetes and Digestive Disorders. and Kidney Diseases (NIDDK) conducts and supports research into many kinds of digestive This publication is not copyrighted. The National disorders, including IBS. The NIDDK and other Digestive Diseases Information Clearinghouse components of the National Institutes of Health (NDDIC) encourages users of this publication to (NIH) are conducting clinical trials aimed at duplicate and distribute as many copies as desired. improving the diagnosis and treatment of IBS. Self This publication is available at Administered Cognitive Behavior Therapy for Irri- www.digestive.niddk.nih.gov. table Bowel Syndrome, funded under NIH clinical trial number NCT00738920, assesses the short- and long-term efficacy of cognitive behavior You may also find additional information about this topic by therapy for IBS using two treatment delivery visiting MedlinePlus at www.medlineplus.gov. systems: self-administered and therapist This publication may contain information about medications. administered. Long-term project goals include When prepared, this publication included the most current development of an effective self-administered information available. For updates or for questions about any medications, contact the U.S. Food and Drug Administration behavioral treatment program that can enhance toll-free at 1-888-INFO-FDA (1-888-463-6332) or visit quality of patient care, improve clinical outcomes, www.fda.gov. Consult your health care provider for more and decrease the economic and personal costs of information. IBS.