Irritable BowelSyndromeNational Digestive Diseases Information ClearinghouseU.S. Departmentof Health andHuman ServicesNATIONALINSTITUTESOF HEALTHWhat is irritable bowelsyndrome (IBS)?Irritable bowel syndrome is a disordercharacterized most commonly by cramping,abdominal pain, bloating, constipation,and diarrhea. IBS causes a great deal ofdiscomfort and distress, but it does not permanentlyharm the intestines and does notlead to a serious disease, such as cancer.Most people can control their symptomswith diet, stress management, and prescribedmedications. For some people,however, IBS can be disabling. They maybe unable to work, attend social events,or even travel short distances.As many as 20 percent of the adult population,or one in five Americans, havesymptoms of IBS, making it one of themost common disorders diagnosed bydoctors. It occurs more often in womenthan in men, and it begins before the ageof 35 in about 50 percent of people.What are the symptomsof IBS?Abdominal pain, bloating, and discomfortare the main symptoms of IBS. However,symptoms can vary from person to person.Some people have constipation, whichmeans hard, difficulttopass, or infrequentbowel movements. Often these peoplereport straining and cramping when tryingto have a bowel movement but cannoteliminate any stool, or they are able toeliminate only a small amount. If they areable to have a bowel movement, it mayhave mucus in it, which is a fluid that moistensand protects passages in the digestivesystem. Some people with IBS experiencediarrhea, which is frequent, loose, waterystools. People with diarrhea frequently feelan urgent and uncontrollable need to havea bowel movement. Other people withIBS alternate between constipation anddiarrhea. Sometimes people find that theirsymptoms subside for a few months andthen return, while others report a constantworsening of symptoms over time.LiverSmallintestineStomachRectumAnusColon(shaded)The colon and rectum are the two main parts of thelarge intestine.
What causes IBS?Researchers have yet to discover any specificcause for IBS. One theory is thatpeople who suffer from IBS have a colonthat is particularly sensitive and reactiveto certain foods and stress. The immunesystem, which fights infection, may also beinvolved.• Normal motility, or movement, maynot be present in the colon of a personwho has IBS. It can be spasmodic orcan even stop working temporarily.Spasms are sudden strong musclecontractions that come and go.• The lining of the colon called theepithelium, which is affected by theimmune and nervous systems, regulatesthe flow of fluids in and out ofthe colon. In IBS, the epitheliumappears to work properly. However,when the contents inside the colonmove too quickly, the colon loses itsability to absorb fluids. The result istoo much fluid in the stool. In otherpeople, the movement inside thecolon is too slow, which causes extrafluid to be absorbed. As a result, aperson develops constipation.• A person’s colon may respondstrongly to stimuli such as certainfoods or stress that would not bothermost people.• Recent research has reported thatserotonin is linked with normal gastrointestinal(GI) functioning. Serotoninis a neurotransmitter, or chemical,that delivers messages from one partof the body to another. Ninety-fivepercent of the serotonin in the body islocated in the GI tract, and the other5 percent is found in the brain. Cellsthat line the inside of the bowel workas transporters and carry the serotoninout of the GI tract. People withIBS, however, have diminished receptoractivity, causing abnormal levelsof serotonin to exist in the GI tract.As a result, they experience problemswith bowel movement, motility, andsensation—having more sensitive painreceptors in their GI tract.• Researchers have reported that IBSmay be caused by a bacterial infectionin the gastrointestinal tract. Studiesshow that people who have had gastroenteritissometimes develop IBS,otherwise called postinfectious IBS.• Researchers have also found very mildceliac disease in some people withsymptoms similar to IBS. People withceliac disease cannot digest gluten,a substance found in wheat, rye, andbarley. People with celiac disease cannoteat these foods without becomingvery sick because their immune systemresponds by damaging the smallintestine. A blood test can determinewhether celiac disease may be present.(For information about celiac disease,see the National Institute of Diabetesand Digestive and Kidney Diseases’[NIDDK’s] Celiac Disease fact sheet.)2 Irritable Bowel Syndrome
How is IBS diagnosed?IBS is generally diagnosed on the basis ofa complete medical history that includesa careful description of symptoms and aphysical examination.No specific test for IBS exists, althoughdiagnostic tests may be performed to ruleout other problems. These tests mayinclude stool sample testing, blood tests,and x rays. Typically, a doctor will performa sigmoidoscopy or colonoscopy, whichallows the doctor to look inside the colonby inserting a small, flexible tube with acamera on the end of it through the anus.The camera then transfers the images ofthe colon onto a large screen for the doctorto see better.If test results are negative, the doctor maydiagnose IBS based on symptoms, includinghow often a person has had abdominalpain or discomfort during the past year,when the pain starts and stops in relationto bowel function, and how bowelfrequency and stool consistency havechanged. Many doctors refer to a list ofspecific symptoms that must be presentto make a diagnosis of IBS.Symptoms include• Abdominal pain or discomfort forat least 12 weeks out of the previous12 months. These 12 weeks do nothave to be consecutive.• The abdominal pain or discomfort hastwo of the following three features:– It is relieved by having a bowelmovement.– When it starts, a change occursin how often a person has a bowelmovement.– When it starts, a change occursin the form of the stool or the wayit looks.• Certain symptoms must also bepresent, such as– a change in frequency of bowelmovements– a change in appearance of bowelmovements– feelings of uncontrollable urgencyto have a bowel movement– difficulty or inability to pass stool– mucus in the stool– bloating• Bleeding, fever, weight loss, and persistentsevere pain are not symptomsof IBS and may indicate other problemssuch as inflammation or, rarely,cancer.The following have been associated with aworsening of IBS symptoms• large meals• bloating from gas in the colon• medicines• wheat, rye, barley, chocolate, milkproducts, or alcohol• drinks with caffeine, such as coffee,tea, or colas• stress, conflict, or emotional upsetsResearchers have found that women withIBS may have more symptoms duringtheir menstrual periods, suggesting thatreproductive hormones can worsen IBSproblems.In addition, people with IBS frequently sufferfrom depression and anxiety, which canworsen symptoms. Similarly, the symptomsassociated with IBS can cause a person tofeel depressed and anxious.3 Irritable Bowel Syndrome
What is the treatmentfor IBS?Unfortunately, many people suffer fromIBS for a long time before seeking medicaltreatment. Up to 70 percent of peoplesuffering from IBS are not receivingmedical care for their symptoms. No curehas been found for IBS, but many optionsare available to treat the symptoms. Thedoctor will prescribe the best treatmentsfor a person’s particular symptoms andencourage the person to manage stress andmake dietary changes.Medications are an important part ofrelieving symptoms. The doctor maysuggest fiber supplements or laxatives forconstipation or medicines to decreasediarrhea, such as diphenoxylate and atropine(Lomotil) or loperamide (Imodium).An antispasmodic is commonly prescribed,which helps control colon musclespasms and reduce abdominal pain. Antidepressantsmay relieve some symptoms.However, both antispasmodics and antidepressantscan worsen constipation, so somedoctors will also prescribe medications thatrelax muscles in the bladder and intestines,such as belladonna alkaloid combinationsand phenobarbital (Donnatal) and chlordiazepoxideand clidinium bromide (Librax).These medications contain a mild sedative,which can be habit forming, so they need tobe used under the guidance of a physician.A medication available specifically to treatIBS is alosetron hydrochloride (Lotronex).Lotronex has been reapproved with significantrestrictions by the U.S. Food andDrug Administration (FDA) for womenwith severe IBS who have not responded toconventional therapy and whose primarysymptom is diarrhea. However, even inthese patients, Lotronex should be usedwith great caution because it can have seriousside effects such as severe constipationor decreased blood flow to the colon.With any medication, even overthecountermedications such as laxativesand fiber supplements, it is important tofollow the doctor’s instructions. Some peoplereport a worsening in abdominal bloatingand gas from increased fiber intake, andlaxatives can be habit forming if they areused too frequently.Medications affect people differently,and no one medication or combinationof medications will work for everyonewith IBS. Working with the doctor tofind the best combination of medicine,diet, counseling, and support to controlsymptoms may be helpful.4 Irritable Bowel Syndrome
How does stress affect IBS?Stress—feeling mentally or emotionallytense, troubled, angry, or overwhelmed—can stimulate colon spasms in people withIBS. The colon has many nerves that connectit to the brain. Like the heart and thelungs, the colon is partly controlled by theautonomic nervous system, which respondsto stress. These nerves control the normalcontractions of the colon and causeabdominal discomfort at stressful times.People often experience cramps or “butterflies”when they are nervous or upset.In people with IBS, the colon can be overlyresponsive to even slight conflict or stress.Stress makes the mind more aware of thesensations that arise in the colon, makingthe person perceive these sensations asunpleasant.Some evidence suggests that IBS is affectedby the immune system, which fights infectionin the body. The immune system isaffected by stress. For all these reasons,stress management is an important partof treatment for IBS. Stress managementoptions include• stress reduction training and relaxationtherapies such as meditation• counseling and support• regular exercise such as walkingor yoga• changes to the stressful situations in aperson’s life• adequate sleepWhat does the colon do?The colon, which is about 5 feet long,connects the small intestine to the rectumand anus. The major function ofthe colon is to absorb water, nutrients,and salts from the partially digestedfood that enters from the small intestine.Two pints of liquid matter enterthe colon from the small intestine eachday. Stool volume is a third of a pint.The difference between the amountof fluid entering the colon from thesmall intestine and the amount of stoolin the colon is what the colon absorbseach day.Colon motility—the contraction of thecolon muscles and the movement ofits contents—is controlled by nerves,hormones, and impulses in the colonmuscles. These contractions move thecontents inside the colon toward therectum. During this passage, waterand nutrients are absorbed into thebody, and what is left over is stool. Afew times each day contractions pushthe stool down the colon, resulting in abowel movement. However, if the musclesof the colon, sphincters, and pelvisdo not contract in the right way, thecontents inside the colon do not movecorrectly, resulting in abdominal pain,cramps, constipation, a sense of incompletestool movement, or diarrhea.5 Irritable Bowel Syndrome
Can changes in diethelp IBS?For many people, careful eating reducesIBS symptoms. Before changing the diet,keep a journal noting the foods that seemto cause distress. Then discuss these findingswith the doctor. A registered dietitiancan help a person make changes to the diet.For instance, if dairy products cause symptomsto flare up, try eating less of thosefoods. A person might be able to tolerateyogurt better than other dairy productsbecause it contains bacteria that supply theenzyme needed to digest lactose, the sugarfound in milk products. Dairy productsare an important source of calcium andother nutrients. If a person needs to avoiddairy products, adequate nutrients shouldbe added in foods or supplements shouldbe taken.In many cases, dietary fiber may lessenIBS symptoms, particularly constipation.However, it may not help with loweringpain or decreasing diarrhea. Whole grainbreads and cereals, fruits, and vegetablesare good sources of fiber. Highfiber dietskeep the colon mildly distended, whichmay help prevent spasms. Some formsof fiber keep water in the stool, therebypreventing hard stools that are difficult topass. Doctors usually recommend a dietwith enough fiber to produce soft, painlessbowel movements. Highfiber diets maycause gas and bloating, although somepeople report that these symptoms go awaywithin a few weeks. Increasing fiber intakeby 2 to 3 grams per day will help reduce therisk of increased gas and bloating.Drinking six to eight glasses of plain watera day is important, especially if a person hasdiarrhea. Drinking carbonated beverages,such as sodas, may result in gas and causediscomfort. Chewing gum and eating tooquickly can lead to swallowing air, whichalso leads to gas.Large meals can cause cramping and diarrhea,so eating smaller meals more often,or eating smaller portions, may help IBSsymptoms. Eating meals that are low in fatand high in carbohydrates such as pasta;rice; wholegrain breads and cereals, unlessa person has celiac disease; fruits; and vegetablesmay help.Is IBS linked to otherhealth problems?As its name indicates, IBS is a syndrome—acombination of signs and symptoms. IBShas not been shown to lead to a seriousdisease, including cancer. Through theyears, IBS has been called by many names,among them colitis, mucous colitis, spasticcolon, or spastic bowel. However, nolink has been established between IBSand inflammatory bowel diseases such asCrohn’s disease or ulcerative colitis.6 Irritable Bowel Syndrome
Points to Remember• IBS is a disorder that interferes withthe normal functions of the colon.The symptoms are crampy abdominalpain, bloating, constipation, anddiarrhea.• IBS is a common disorder foundmore often in women than men.• People with IBS have colons that aremore sensitive and reactive to thingsthat might not bother other people,such as stress, large meals, gas,medicines, certain foods, caffeine,or alcohol.• IBS is diagnosed by its signs andsymptoms and by the absence ofother diseases.• Most people can control their symptomsby taking medicines such aslaxatives, antidiarrhea medicines,antispasmodics, or antidepressants;reducing stress; and changing theirdiet.• IBS does not harm the intestinesand does not lead to cancer. It isnot related to Crohn’s disease orulcerative colitis.Hope through ResearchThe NIDDK conducts and supportsresearch into many kinds of digestivedisorders including IBS. Researchersare studying gastrointestinal motility andsensitivity to find possible treatments forIBS. These studies include the structureand contraction of gastrointestinal muscles,as well as the mechanics of fluid movementthrough the intestines. Understanding theinfluence of the nerves, hormones, andinflammation in IBS may lead to new treatmentsto better control the symptoms.Participants in clinical trials can play amore active role in their own health care,gain access to new research treatmentsbefore they are widely available, and helpothers by contributing to medical research.For information about current studies, visitwww.ClinicalTrials.gov.The U.S. Government does not endorse or favor anyspecific commercial product or company. Trade,proprietary, or company names appearing in thisdocument are used only because they are considerednecessary in the context of the information provided.If a product is not mentioned, the omission does notmean or imply that the product is unsatisfactory.7 Irritable Bowel Syndrome
For More InformationInternational Foundation for FunctionalGastrointestinal DisordersP.O. Box 170864Milwaukee, WI 53217–8076Phone: 1–888–964–2001Fax: 414–964–7176Email: firstname.lastname@example.orgInternet: www.iffgd.orgAcknowledgmentsPublications produced by the Clearinghouseare carefully reviewed by bothNIDDK scientists and outside experts.You may also find additional information about thistopic by visiting MedlinePlus at www.medlineplus.gov.This publication may contain information aboutmedications. When prepared, this publicationincluded the most current information available.For updates or for questions about any medications,contact the U.S. Food and Drug Administrationtoll-free at 1–888–INFO–FDA (1–888–463–6332) orvisit www.fda.gov. Consult your doctor for moreinformation.National Digestive DiseasesInformation Clearinghouse2 Information WayBethesda, MD 20892–3570Phone: 1–800–891–5389TTY: 1–866–569–1162Fax: 703–738–4929Email: email@example.comInternet: www.digestive.niddk.nih.govThe National Digestive DiseasesInformation Clearinghouse (NDDIC)is a service of the National Instituteof Diabetes and Digestive and KidneyDiseases (NIDDK). The NIDDKis part of the National Institutes of Healthof the U.S. Department of Health andHuman Services. Established in 1980, theClearinghouse provides information aboutdigestive diseases to people with digestivedisorders and to their families, healthcare professionals, and the public. TheNDDIC answers inquiries, develops anddistributes publications, and works closelywith professional and patient organizationsand Government agencies to coordinateresources about digestive diseases.This publication is not copyrighted. The Clearinghouseencourages users of this publication to duplicateand distribute as many copies as desired.This publication is available atwww.digestive.niddk.nih.gov.U.S. DEPARTMENT OF HEALTHAND HUMAN SERVICESNational Institutes of HealthNIH Publication No. 07–693September 2007