What I need to know about

Irritable Bowel Syndrome

National Digestive Diseases 

Information Clearinghouse

What I need to know about

Irritable Bowel Syndrome
Contents

What is irritable bowel syndrome (IBS)?.............. 1

What are the symptoms of IBS? ............................ 2

What causes IBS?.................................................... 5

How is IBS diagnosed? ........................................... 7

How is IBS treated? .............................................. 12

Eating, Diet, and Nutrition .................................. 12

Does stress cause IBS? ......................................... 18

Points to Remember............................................. 19

Hope through Research ....................................... 21

Pronunciation Guide............................................. 22

For More Information .......................................... 24

Acknowledgments................................................. 25
1

What is irritable bowel syndrome (IBS)?

Irritable bowel syndrome* is a functional 

gastrointestinal (GI) disorder, meaning symptoms 

are caused by changes in how the GI tract works. 

The GI tract is a series of hollow organs joined in 

a long, twisting tube from the mouth to the anus—

the opening through which stool leaves your body. 

Food is digested, or broken down, in the GI tract. 

*See the Pronunciation Guide for tips on how to 

say the words in bold type.

Large 

intestine

Esophagus

Stomach

Small 

intestine

Mouth

Appendix

Rectum Anus

The organs of the GI tract
2

IBS is a group of symptoms that occur together, 

not a disease. Symptoms can come and go 

repeatedly without signs of damage to the GI tract.

What are the symptoms of IBS?

The most common symptoms of IBS include pain 

or discomfort in your abdomen—the area between 

your chest and hips—and changes in your bowel 

habits. The pain or discomfort of IBS may be 

reported as cramping and

● starts when you have bowel movements more or 

less often than usual

● starts when your stool appears looser and more 

watery or harder and more lumpy than usual

● goes away after a bowel movement
3

The changes in bowel habits with IBS may be 

diarrhea, constipation, or both.

Symptoms of diarrhea are

● passing stools three or more times a day

● having loose, watery stools

● feeling an urgent need to have a bowel 

movement

Symptoms of constipation are

● passing fewer than three stools in a week

● having hard, dry stools

● straining to have a bowel movement

Some people with IBS have only diarrhea or only 

constipation. Some people have symptoms of 

both diarrhea and constipation or have diarrhea 

sometimes and constipation other times. People 

often have symptoms after eating a meal.
4

Other symptoms of IBS are

● whitish mucus—a clear liquid made by the 

intestines—in the stool

● a swollen or bloated abdomen

● the feeling that you haven’t finished a bowel 

movement

Women with IBS often have more symptoms 

during their menstrual periods.

IBS is a chronic disorder, meaning it lasts a long 

time, often years. However, the symptoms may 

come and go. You may have IBS if

● you have had symptoms at least three times a 

month for the past 3 months

● your symptoms first started at least 6 months ago

While IBS can be painful, it doesn’t lead to other 

health problems or damage the GI tract.
5

What causes IBS?

Doctors are not sure what causes IBS. Researchers 

are studying the following possible causes of IBS:

● Brain-gut signal problems. Signals between your 

brain and the nerves of your gut, or small and 

large intestines, control how your gut works. 

Problems with brain-gut signals may cause IBS 

symptoms, such as changes in your bowel habits 

and pain or discomfort.

● Colon muscle problems. The muscles of your 

colon, part of your large intestine, may not 

work normally. The muscles may contract, or 

tighten, too much. These contractions may 

move stool through your gut too quickly, causing 

cramping and diarrhea during or shortly after 

a meal, or slow the movement of stool, causing 

constipation.

● Sensitive nerves. The nerves in your gut may be 

extra sensitive, causing you to feel more pain or 

discomfort than normal when gas or stool is in 

the gut.
6

● Mental health issues. Psychological, or mental 

health, issues such as anxiety or depression may 

be related to IBS in some people. Stress can 

make the nerves of your gut more sensitive, 

causing more discomfort and emotional distress.

● Infections. A bacterial infection in the GI tract 

may cause some people to develop IBS.

● Small intestinal bacterial overgrowth. Normally, 

few bacteria live in the small intestine. Small 

intestinal bacterial overgrowth is an increase in 

the number or a change in the type of bacteria in 

the small intestine. These bacteria can produce 

extra gas and may also cause diarrhea and weight 

loss. Some researchers believe small intestinal 

bacterial overgrowth may lead to IBS; however, 

more research is needed to show a link between 

the two conditions.
7

How is IBS diagnosed?

Your doctor may be able to diagnose IBS based on 

your symptoms. Your doctor may not need to do 

medical tests or may do a limited number of tests.

Your doctor will ask about your

● medical history

● eating habits

● medicine use
8

Your doctor will look for a certain pattern in your 

symptoms. Your doctor can diagnose IBS by 

using symptom-based standards such as the Rome 

criteria. Based on the Rome criteria, IBS may be 

diagnosed if

● your symptoms started at least 6 months ago

● you have had abdominal pain or discomfort at 

least three times a month for the past 3 months

● your abdominal pain or discomfort has two or 

three of the following features: 

•	Your pain or discomfort improves after a 

bowel movement.

•	When your pain or discomfort starts, you 

notice a change in how often you have a bowel 

movement.

•	When your pain or discomfort starts, you 

notice a change in the way your stools look.
9

Your doctor will also conduct a physical exam and 

may perform blood tests to make sure you don’t 

have other health problems. IBS can have the 

same symptoms as other health problems, so more 

tests may be needed. If any blood tests suggest 

you may have another health problem, your doctor 

might also perform the following tests:

● Stool test. A stool test is used to check stool 

for blood or parasites, which are tiny organisms 

found in contaminated food or water. Your 

doctor will give you a container for catching 

and storing the stool. You will return the stool 

sample to your doctor or a commercial facility. 

The sample will be sent to a lab to check for 

blood or parasites. Your doctor may also check 

for blood in stool by examining your rectum—

the lower end of the large intestine leading to 

the anus—during your physical exam.
10

● Flexible sigmoidoscopy. Flexible sigmoidoscopy 

is used to look inside your rectum and lower 

colon. The test is performed at a hospital or 

an outpatient center by a gastroenterologist—a 

doctor who specializes in digestive diseases. 

Anesthesia is usually not needed. Your doctor 

will give you written bowel prep instructions to 

follow at home before the test. You may need 

to follow a clear liquid diet for 1 to 3 days before 

the test. You may also need a laxative or an 

enema the night before the test. You may also 

have one or more enemas about 2 hours before 

the procedure.

For the test, you will lie on a table while the 

doctor inserts a flexible tube into your anus. A 

small camera on the tube sends a video image of 

your intestinal lining to a computer screen. The 

test can show problems in your rectum or lower 

colon that may be causing your symptoms.

You can usually go back to your normal diet 

after the test, though you may have cramping or 

bloating during the first hour after the test.
11

● Colonoscopy. Colonoscopy is used to look 

inside your rectum and entire colon. The test is 

performed at a hospital or an outpatient center 

by a gastroenterologist. You’ll be given a light 

sedative and possibly pain medicine to help you 

relax. Your doctor will give you written bowel 

prep instructions to follow at home before the 

test. You may need to follow a clear liquid diet 

for 1 to 3 days before the test. You may need 

to take laxatives and enemas the evening before 

the test.

For the test, you will lie on a table while the 

doctor inserts a flexible tube into your anus. A 

small camera on the tube sends a video image of 

your intestinal lining to a computer screen. The 

test can show problems in your colon that may 

be causing your symptoms.

Cramping or bloating may occur during the first 

hour after the test. Driving is not permitted for 

24 hours after the test so that the sedative can 

wear off. Before the appointment, you should 

make plans for a ride home. By the next day, 

you should fully recover and go back to your 

normal diet.
12

How is IBS treated?

Irritable bowel syndrome is treated by relieving 

symptoms through

● changes in eating, diet, and nutrition

● medicine

● probiotics

● psychological therapy

You may have to try a few treatments to see what 

works best for you. Your doctor can help you find 

the right treatment plan.

Eating, Diet, and Nutrition

Eating large meals can cause cramping and 

diarrhea in some people with IBS. If you 

experience these symptoms, try to change your 

eating patterns by eating four or five small meals 

a day.
13

Certain foods or drinks may make symptoms 

worse, such as

● foods high in fat

● some milk products

● drinks with alcohol or caffeine

● drinks with large amounts of artificial 

sweeteners, which are used in place of sugar

● beans, cabbage, and other foods that may 

cause gas

To find out if certain foods trigger your symptoms, 

keep a diary and track

● what you eat during the day

● what symptoms you have

● when symptoms occur
14

Take your notes to your doctor and talk about 

which foods seem to make your symptoms worse. 

You may need to avoid these foods or eat less of 

them.

Fiber may improve constipation symptoms caused 

by IBS because it makes stool soft and easier to 

pass. Fiber is found in foods such as whole-grain 

breads and cereals, beans, fruits, and vegetables. 

The Academy of Nutrition and Dietetics 

recommends that adults consume 21 to 38 grams 

of fiber a day.

While fiber may help constipation, it may not be 

enough to treat the abdominal discomfort or pain 

of IBS. In fact, some people with IBS may feel a 

bit more abdominal discomfort after adding more 

fiber to their diet. Add foods with fiber a little 

at a time to let your body get used to them. Too 

much fiber at once can cause gas, which can trigger 

symptoms in people with IBS.

Medicine

Your doctor may give you medicine to help relieve 

symptoms. Follow your doctor’s instructions when 

you use medicine to treat IBS. Talk with your 

doctor about possible side effects and what to do if 

you have them.
15

These medicines can lessen the symptoms of IBS:

● Laxatives treat constipation. Many kinds of 

laxatives are available. Your doctor can help you 

find the right laxative for you.

● Loperamide (Imodium) treats diarrhea.

● Antispasmodics help reduce muscle spasms in 

the intestines and ease abdominal pain.

● Antidepressants in low doses can help relieve 

IBS symptoms.

● Lubiprostone (Amitiza) is prescribed for people 

who have IBS with constipation.

● Linaclotide (Linzess) is also prescribed for 

people who have IBS with constipation.

The antibiotic rifaximin can reduce bloating by 

treating small intestinal bacterial overgrowth; 

however, scientists are still debating the use of 

antibiotics to treat IBS and more research is needed.
16

Probiotics

Probiotics are live microorganisms—tiny organisms 

that can be seen only with a microscope. These 

microorganisms, most often bacteria, are like the 

microorganisms normally found in your GI tract. 

Studies have found that probiotics taken in large 

enough amounts improve symptoms of IBS; 

however, more research is needed. Probiotics 

can be found in dietary supplements, such as 

capsules, tablets, and powders, and in some foods, 

such as yogurt. Talk with your doctor before 

using probiotics, supplements, or any other 

complementary or alternative medical treatment. 

Read more at www.nccam.nih.gov/health/probiotics.
17

Psychological Therapy

Psychological therapy can help improve IBS 

symptoms.

● Talk therapy. Talk therapy may reduce stress 

and improve IBS symptoms. Two types of 

talk therapy used to treat IBS are cognitive

behavioral therapy and psychodynamic, or 

interpersonal, therapy. Cognitive behavioral 

therapy focuses on your thoughts and actions. 

Psychodynamic therapy focuses on how your 

emotions affect your IBS symptoms. This type 

of therapy often involves techniques to help you 

relax and manage stress.

● Gut-directed hypnotherapy. In hypnotherapy,

a therapist may help relax the muscles in your 

colon by putting you into a trancelike state. 

● Mindfulness training. Mindfulness training 

can teach you to focus your attention on 

sensations occurring at the moment and to avoid 

catastrophizing, or worrying about the meaning 

of those sensations.
18

Does stress cause IBS?

Although stress does not cause IBS, if you already 

have IBS, stress can make your symptoms worse. 

In addition, simply having IBS symptoms can 

produce stress.

Learning to reduce stress can help improve 

IBS. With less stress, you may find you have less 

cramping and pain. You may also find it easier to 

manage your symptoms.

Meditation, exercise, hypnosis, and counseling 

may help lessen IBS symptoms. Getting enough 

sleep and changing life situations to make them 

less stressful may also help. You may need to try 

different activities to see what works best for you.
19

Points to Remember

● Irritable bowel syndrome (IBS) is a functional 

gastrointestinal (GI) disorder, meaning 

symptoms are caused by changes in how the 

GI tract works.

● IBS is a group of symptoms that occur together, 

not a disease. Symptoms can come and go 

repeatedly without signs of damage to the 

GI tract.

● The most common symptoms of IBS include 

pain or discomfort in your abdomen—the area 

between your chest and hips—and changes in 

your bowel habits. 

● While IBS can be painful, it doesn’t lead to other 

health problems or damage the GI tract.

● Doctors are not sure what causes IBS. 

Researchers are studying the following possible 

causes of IBS:

•	brain-gut signal problems

•	 colon muscle problems

•	sensitive nerves

•	mental health issues

•	infections

•	small intestinal bacterial overgrowth 
20

● Your doctor may be able to diagnose IBS based 

on your symptoms. Your doctor may not need to 

do medical tests or may do a limited number of 

tests.

● IBS is treated by relieving symptoms through

•	 changes in eating, diet, and nutrition

•	medicine

•	probiotics

•	psychological therapy

● Although stress does not cause IBS, if you 

already have IBS, stress can make your 

symptoms worse.
21

Hope through Research

The National Institute of Diabetes and Digestive 

and Kidney Diseases’ (NIDDK’s) Division of 

Digestive Diseases and Nutrition conducts and 

supports basic and clinical research into many 

digestive disorders. 

Clinical trials are research studies involving people. 

Clinical trials look at safe and effective new ways 

to prevent, detect, or treat disease. Researchers 

also use clinical trials to look at other aspects 

of care, such as improving the quality of life for 

people with chronic illnesses. To learn more 

about clinical trials, why they matter, and how to 

participate, visit the NIH Clinical Research Trials 

and You website at www.nih.gov/health/clinicaltrials.

For information about current studies, visit 

www.ClinicalTrials.gov.
22

Pronunciation Guide

abdomen (AB-doh-men)

abdominal (ab-DOM-ih-nuhl)

antidepressants (AN-tee-dee-PRESS-uhnts)

antispasmodics (AN-tee-spaz-MOD-iks)

anus (AY-nuhss)

chronic (KRON-ik)

cognitive (KOG-nih-tiv)

colon (KOH-lon)

colonoscopy (KOH-lon-OSS-kuh-pee)

constipation (KON-stih-PAY-shuhn)

diarrhea (DY-uh-REE-uh)

enema (EN-uh-muh)

flexible sigmoidoscopy (FLEK-suh-buhl)

 (SIG-moy-DOSS-kuh-pee)
23

functional (FUHNK-shuhn-uhl)

gastroenterologist (GASS-troh-EN-tur-OL-uh-jist)

gastrointestinal (GASS-troh-in-TESS-tin-uhl)

hypnotherapy (HIP-noh-THAIR-uh-pee)

interpersonal (IN-tur-PUR-suhn-uhl)

intestines (in-TESS-tinz)

irritable bowel syndrome (IHR-ih-tuh-buhl) (boul) 

 (SIN-drohm)

laxative (LAK-suh-tiv)

mucus (MYOO-kuhss)

probiotics (PROH-by-OT-iks)

psychodynamic (SY-koh-dy-NAM-ik)

psychological (SY-koh-LOJ-ih-kuhl)
24

For More Information

American Neurogastroenterology 

and Motility Society

45685 Harmony Lane 

Belleville, MI 48111 

Phone: 734–699–1130 

Fax: 734–699–1136 

Email: admin@motilitysociety.org 

Internet: www.motilitysociety.org 

International Foundation for Functional 

Gastrointestinal Disorders

700 West Virginia Street, Suite 201

Milwaukee, WI 53204

Phone: 1–888–964–2001 or 414–964–1799

Fax: 414–964–7176

Email: iffgd@iffgd.org

Internet: www.iffgd.org 

Rome Foundation, Inc.

P.O. Box 6524 

Raleigh, NC 27628 

Phone: 919–539–3051 

Fax: 919–900–7646 

Email: mpickard@theromefoundation.org 

Internet: www.romecriteria.org 
25

Acknowledgments

Publications produced by the Clearinghouse are 

carefully reviewed by both NIDDK scientists and 

outside experts. This publication was reviewed by 

Douglas A. Drossman, M.D., University of North 

Carolina at Chapel Hill.

Thank you also to the Salvation Army, SE Corps, 

Washington, D.C., for facilitating field-testing of 

the original version of this publication.

The U.S. Government does not endorse or favor any specific 

commercial product or company. Trade, proprietary, or 

company names appearing in this document are used only 

because they are considered necessary in the context of 

the information provided. If a product is not mentioned, 

the omission does not mean or imply that the product is 

unsatisfactory. 

National Digestive Diseases 

Information Clearinghouse

2 Information Way

Bethesda, MD 20892–3570

Phone: 1–800–891–5389

TTY: 1–866–569–1162

Fax: 703–738–4929

Email: nddic@info.niddk.nih.gov

Internet: www.digestive.niddk.nih.gov

The National Digestive Diseases Information Clearinghouse 

(NDDIC) is a service of the National Institute of Diabetes and 

Digestive and Kidney Diseases (NIDDK). The NIDDK is part of 

the National Institutes of Health of the U.S. Department of Health 

and Human Services. Established in 1980, the Clearinghouse 

provides information about digestive diseases to people with 

digestive disorders and to their families, health care professionals, 

and the public. The NDDIC answers inquiries, develops and 

distributes publications, and works closely with professional and 

patient organizations and Government agencies to coordinate 

resources about digestive diseases.

This publication is not copyrighted. The Clearinghouse 

encourages users of this publication to duplicate and distribute 

as many copies as desired.

This publication is available at www.digestive.niddk.nih.gov.

This publication may contain information about medications 

and, when taken as prescribed, the conditions they treat. When 

prepared, this publication included the most current information 

available. For updates or for questions about any medications, 

contact the U.S. Food and Drug Administration toll-free at 1–888–

INFO–FDA (1–888–463–6332) or visit www.fda.gov. Consult your 

health care provider for more information.
NIH Publication No. 13–4686

September 2013

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