What is irritable bowel syndrome (IBS)?
Irritable
bowel syndrome is a disorder characterized most commonly by cramping,
abdominal pain, bloating, constipation, and diarrhea. IBS causes a great
deal of discomfort and distress, but it does not permanently harm the
intestines and does not lead to a serious disease, such as cancer. Most
people can control their symptoms with diet, stress management, and
prescribed medications. For some people, however, IBS can be disabling.
They may be 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,
have symptoms of IBS, making it one of the most common disorders
diagnosed by doctors. It occurs more often in women than in men, and it
begins before the age of 35 in about 50 percent of people.
What are the symptoms of IBS?
Abdominal
pain, bloating, and discomfort are the main symptoms of IBS. However,
symptoms can vary from person to person. Some people have constipation,
which means hard, difficult-to-pass, or infrequent bowel movements.
Often these people report straining and cramping when trying to have a
bowel movement but cannot eliminate any stool, or they are able to
eliminate only a small amount. If they are able to have a bowel
movement, there may be mucus in it, which is a fluid that moistens and
protect passages in the digestive system. Some people with IBS
experience diarrhea, which is frequent, loose, watery, stools. People
with diarrhea frequently feel an urgent and uncontrollable need to have a
bowel movement. Other people with IBS alternate between constipation
and diarrhea. Sometimes people find that their symptoms subside for a
few months and then return, while others report a constant worsening of
symptoms over time.
What causes IBS?
Researchers
have yet to discover any specific cause for IBS. One theory is that
people who suffer from IBS have a colon, or large intestine, that is
particularly sensitive and reactive to certain foods and stress. The
immune system, which fights infection, may also be involved
· Normal
motility, or movement, may not be present in the colon of a person who
has IBS. It can be spasmodic or can even stop working temporarily.
Spasms are sudden strong muscle contractions that come and go.
· The
lining of the colon called the epithelium, which is affected by the
immune and nervous systems, regulates the flow of fluids in and out of
the colon. In IBS, the epithelium appears to work properly. However,
when the contents inside the colon move too quickly, the colon loses its
ability to absorb fluids. The result is too much fluid in the stool. In
other people, the movement inside the colon is too slow, which causes
extra fluid to be absorbed. As a result, a person develops constipation.
· A person’s colon may respond strongly to stimuli such as certain foods or stress that would not bother most people.
· Recent
research has reported that serotonin is linked with normal
gastrointestinal (GI) functioning. Serotonin is a neurotransmitter, or
chemical, that delivers messages from one part of your body to another.
Ninety-five percent of the serotonin in your body is located in the GI
tract, and the other 5 percent is found in the brain. Cells that line
the inside of the bowel work as transporters and carry the serotonin out
of the GI tract. People with IBS, however, have diminished receptor
activity, causing abnormal levels of serotonin to exist in the GI tract.
As a result, they experience problems with bowel movement, motility,
and sensation—having more sensitive pain receptors in their GI tract.
· Researchers
have reported that IBS may be caused by a bacterial infection in the
gastrointestinal tract. Studies show that people who have had
gastroenteritis sometimes develop IBS, otherwise called post-infectious
IBS.
· Researchers
have also found very mild celiac disease in some people with symptoms
similar to IBS. People with celiac disease cannot digest gluten, a
substance found in wheat, rye, and barley. People with celiac disease
cannot eat these foods without becoming very sick because their immune
system responds by damaging the small intestine. A blood test can
determine whether celiac disease may be present. (For information about
celiac disease, see the NIDDK’s Celiac Disease fact sheet.)
How is IBS diagnosed?
If
you think you have IBS, seeing your doctor is the first step. IBS is
generally diagnosed on the basis of a complete medical history that
includes a careful description of symptoms and a physical examination.
There
is no specific test for IBS, although diagnostic tests may be performed
to rule out other problems. These tests may include stool sample
testing, blood tests, and x rays. Typically, a doctor will perform a
sigmoidoscopy, or colonoscopy, which allows the doctor to look inside
the colon. This is done by inserting a small, flexible tube with a
camera on the end of it through the anus. The camera then transfers the
images of your colon onto a large screen for the doctor to see well.
If
your test results are negative, the doctor may diagnose IBS based on
your symptoms, including how often you have had abdominal pain or
discomfort during the past year, when the pain starts and stops in
relation to bowel function, and how your bowel frequency and stool
consistency have changed. Many doctors refer to a list of specific
symptoms that must be present to make a diagnosis of IBS.
Symptoms include
· Abdominal pain or discomfort for at least 12 weeks out of the previous 12 months. These 12 weeks do not have to be consecutive.
· The abdominal pain or discomfort has two of the following three features:
- It is relieved by having a bowel movement.
- When it starts, there is a change in how often you have a bowel movement.
- When it starts, there is a change in the form of the stool or the way it looks.
· Certain symptoms must also be present, such as
- a change in frequency of bowel movements
- a change in appearance of bowel movements
- feelings of uncontrollable urgency to have a bowel movement
- difficulty or inability to pass stool
- mucus in the stool
- bloating
· Bleeding,
fever, weight loss, and persistent severe pain are not symptoms of IBS
and may indicate other problems such as inflammation, or rarely, cancer.
The following have been associated with a worsening of IBS symptoms
- large meals
- bloating from gas in the colon
- medicines
- wheat, rye, barley, chocolate, milk products, or alcohol
- drinks with caffeine, such as coffee, tea, or colas
- stress, conflict, or emotional upsets
Researchers
have found that women with IBS may have more symptoms during their
menstrual periods, suggesting that reproductive hormones can worsen IBS
problems.
In
addition, people with IBS frequently suffer from depression and
anxiety, which can worsen symptoms. Similarly, the symptoms associated
with IBS can cause a person to feel depressed and anxious.
What is the treatment for IBS?
Unfortunately,
many people suffer from IBS for a long time before seeking medical
treatment. Up to 70 percent of people suffering from IBS are not
receiving medical care for their symptoms. No cure has been found for
IBS, but many options are available to treat the symptoms. Your doctor
will give you the best treatments for your particular symptoms and
encourage you to manage stress and make changes to your diet.
Medications
are an important part of relieving symptoms. Your doctor may suggest
fiber supplements or laxatives for constipation or medicines to decrease
diarrhea, such as Lomotil or loperamide (Imodium). An antispasmodic is
commonly prescribed, which helps to control colon muscle spasms and
reduce abdominal pain. Antidepressants may relieve some symptoms.
However, both antispasmodics and antidepressants can worsen
constipation, so some doctors will also prescribe medications that relax
muscles in the bladder and intestines, such as Donnapine and Librax.
These medications contain a mild sedative, which can be habit forming,
so they need to be used under the guidance of a physician.
A
medication available specifically to treat IBS is alosetron
hydrochloride (Lotronex). Lotronex has been re-approved with significant
restrictions by the U.S. Food and Drug Administration (FDA) for women
with severe IBS who have not responded to conventional therapy and whose
primary symptom is diarrhea. However, even in these patients, Lotronex
should be used with great caution because it can have serious side
effects such as severe constipation or decreased blood flow to the
colon.
With
any medication, even over-the-counter medications such as laxatives and
fiber supplements, it is important to follow your doctor’s
instructions. Some people report a worsening in abdominal bloating and
gas from increased fiber intake, and laxatives can be habit forming if
they are used too frequently.
Medications
affect people differently, and no one medication or combination of
medications will work for everyone with IBS. You will need to work with
your doctor to find the best combination of medicine, diet, counseling,
and support to control your symptoms.
How does stress affect IBS?
Stress—feeling
mentally or emotionally tense, troubled, angry, or overwhelmed—can
stimulate colon spasms in people with IBS. The colon has many nerves
that connect it to the brain. Like the heart and the lungs, the colon is
partly controlled by the autonomic nervous system, which responds to
stress. These nerves control the normal contractions of the colon and
cause abdominal discomfort at stressful times. People often experience
cramps or “butterflies” when they are nervous or upset. In people with
IBS, the colon can be overly responsive to even slight conflict or
stress. Stress makes the mind more aware of the sensations that arise in
the colon, making the person perceive these sensations as unpleasant.
Some
evidence suggests that IBS is affected by the immune system, which
fights infection in the body. The immune system is affected by stress.
For all these reasons, stress management is an important part of
treatment for IBS. Stress management options include
- stress reduction (relaxation) training and relaxation therapies such as meditation
- counseling and support
- regular exercise such as walking or yoga
- changes to the stressful situations in your life
- adequate sleep
What does the colon do?
The
colon, which is about 5 feet long, connects the small intestine to the
rectum and anus. The major function of the colon is to absorb water,
nutrients, and salts from the partially digested food that enters from
the small intestine. Two pints of liquid matter enter the colon from the
small intestine each day. Stool volume is a third of a pint. The
difference between the amount of fluid entering the colon from the small
intestine and the amount of stool in the colon is what the colon
absorbs each day.
Colon
motility—the contraction of the colon muscles and the movement of its
contents—is controlled by nerves, hormones, and impulses in the colon
muscles. These contractions move the contents inside the colon toward
the rectum. During this passage, water and nutrients are absorbed into
the body, and what is left over is stool. A few times each day
contractions push the stool down the colon, resulting in a bowel
movement. However, if the muscles of the colon, sphincters, and pelvis
do not contract in the right way, the contents inside the colon do not
move correctly, resulting in abdominal pain, cramps, constipation, a
sense of incomplete stool movement, or diarrhea.
Can changes in diet help IBS?
For
many people, careful eating reduces IBS symptoms. Before changing your
diet, keep journals noting the foods that seem to cause distress. Then
discuss your findings with your doctor. You may want to consult a
registered dietitian who can help you make changes to your diet. For
instance, if dairy products cause your symptoms to flare up, you can try
eating less of those foods. You might be able to tolerate yogurt better
than other dairy products because it contains bacteria that supply the
enzyme needed to digest lactose, the sugar found in milk products. Dairy
products are an important source of calcium and other nutrients. If you
need to avoid dairy products, be sure to get adequate nutrients in the
foods you substitute, or take supplements.
In
many cases, dietary fiber may lessen IBS symptoms, particularly
constipation. However, it may not help with lowering pain or decreasing
diarrhea. Whole grain breads and cereals, fruits, and vegetables are
good sources of fiber. High-fiber diets keep the colon mildly distended,
which may help prevent spasms. Some forms of fiber keep water in the
stool, thereby preventing hard stools that are difficult to pass.
Doctors usually recommend a diet with enough fiber to produce soft,
painless bowel movements. High-fiber diets may cause gas and bloating,
although some people report that these symptoms go away within a few
weeks. (For information about diets for people with celiac disease,
please see the NIDDK’s Celiac Disease fact sheet.) Increasing fiber intake by 2 to 3 grams per day will help reduce the risk of increased gas and bloating.
Drinking
six to eight glasses of plain water a day is important, especially if
you have diarrhea. Drinking carbonated beverages, such as sodas, may
result in gas and cause discomfort. Chewing gum and eating too quickly
can lead to swallowing air, which also leads to gas.
Large
meals can cause cramping and diarrhea, so eating smaller meals more
often, or eating smaller portions, may help IBS symptoms. Eating meals
that are low in fat and high in carbohydrates such as pasta, rice,
whole-grain breads and cereals (unless you have celiac disease), fruits,
and vegetables may help.
Is IBS linked to other health problems?
As
its name indicates, IBS is a syndrome—a combination of signs and
symptoms. IBS has not been shown to lead to a serious disease, including
cancer. Through the years, IBS has been called by many names, among
them colitis, mucous colitis, spastic colon, or spastic bowel. However,
no link has been established between IBS and inflammatory bowel diseases
such as Crohn’s disease or ulcerative colitis.
Points to Remember
· IBS
is a disorder that interferes with the normal functions of the colon.
The symptoms are crampy abdominal pain, bloating, constipation, and
diarrhea.
· IBS is a common disorder found more often in women than men.
· People
with IBS have colons that are more sensitive and reactive to things
that might not bother other people, such as stress, large meals, gas,
medicines, certain foods, caffeine, or alcohol.
· IBS is diagnosed by its signs and symptoms and by the absence of other diseases.
· Most
people can control their symptoms by taking medicines such as
laxatives, antidiarrhea medicines, antispasmodics, or antidepressants;
reducing stress; and changing their diet.
· IBS does not harm the intestines and does not lead to cancer. It is not related to Crohn’s disease or ulcerative colitis.