Article title: Constipation: NIDDK
Conditions: Constipation, colon, rectum
is passage of small amounts of hard, dry bowel movements, usually fewer
than three times a week. People who are constipated may find it difficult
and painful to have a bowel movement. Other symptoms of constipation
include feeling bloated, uncomfortable, and sluggish.
Many people think they are constipated when, in fact, their bowel
movements are regular. For example, some people believe they are
constipated, or irregular, if they do not have a bowel movement every day.
However, there is no right number of daily or weekly bowel movements.
Normal may be three times a day or three times a week depending on the
person. In addition, some people naturally have firmer stools than others.
At one time or another almost everyone gets constipated. Poor diet and
lack of exercise are usually the causes. In most cases, constipation is
temporary and not serious. Understanding causes, prevention, and treatment
will help most people find relief.
Who Gets Constipated?
According to the 1991 National Health Interview
Survey, about 4 1/2 million people in the United States say they are
constipated most or all of the time. Those reporting constipation most
often are women, children, and adults age 65 and over. Pregnant women also
complain of constipation, and it is a common problem following childbirth
Constipation is the most common gastrointestinal complaint in the
United States, resulting in about 2 million annual visits to the doctor.
However, most people treat themselves without seeking medical help, as is
evident from the $725 million Americans spend on laxatives each year.
What Causes Constipation?
To understand constipation, it helps to know how
the colon (large intestine) works.
As food moves through it, the colon
absorbs water while forming waste products, or stool. Muscle contractions
in the colon push the stool toward the rectum. By the time stool reaches
the rectum, it is solid because most of the water has been absorbed.
The hard and dry stools of constipation occur when the colon absorbs
too much water. This happens because the colon's muscle contractions are
slow or sluggish, causing the stool to move through the colon too slowly.
Figure 2 lists the most common causes of constipation.
Common Causes of Constipation
- Not enough fiber in diet
- Not enough liquids
- Lack of exercise
- Irritable bowel syndrome
- Changes in life or routine such as pregnancy, older age,
- Abuse of laxatives
- Ignoring the urge to have a bowel movement
- Specific diseases such as multiple sclerosis and lupus
- Problems with the colon and rectum
- Problems with intestinal function (Chronic idiopathic
The most common cause of constipation is a diet low in fiber
found in vegetables, fruits, and whole grains and high in fats found in
cheese, eggs, and meats. People who eat plenty of high-fiber foods are
less likely to become constipated.
Fiber--soluble and insoluble--is the part of fruits, vegetables, and
grains that the body cannot digest. Soluble fiber dissolves easily in
water and takes on a soft, gel-like texture in the intestines. Insoluble
fiber passes almost unchanged through the intestines. The bulk and soft
texture of fiber help prevent hard, dry stools that are difficult to pass.
On average, Americans eat about 5 to 20 grams of fiber daily, short of
the 20 to 35 grams recommended by the American Dietetic Association. Both
children and adults eat too many refined and processed foods in which the
natural fiber is removed.
A low-fiber diet also plays a key role in constipation among older
adults. They often lack interest in eating and may choose fast foods low
in fiber. In addition, loss of teeth may force older people to eat soft
foods that are processed and low in fiber.
Not Enough Liquids
Liquids like water and juice add fluid to the
colon and bulk to stools, making bowel movements softer and easier to
pass. People who have problems with constipation should drink enough of
these liquids every day, about eight 8-ounce glasses. Other liquids, like
coffee and soft drinks, that contain caffeine seem to have a dehydrating
Lack of Exercise
Lack of exercise can lead to constipation,
although doctors do not know precisely why. For example, constipation
often occurs after an accident or during an illness when one must stay in
bed and cannot exercise.
Pain medications (especially narcotics), antacids that
contain aluminum, antispasmodics, antidepressants, iron supplements,
diuretics, and anticonvulsants for epilepsy can slow passage of bowel
Irritable Bowel Syndrome (IBS)
Some people with IBS, also known as
spastic colon, have spasms in the colon that affect bowel movements.
Constipation and diarrhea often alternate, and abdominal cramping,
gassiness, and bloating are other common complaints. Although IBS can
produce lifelong symptoms, it is not a life-threatening condition. It
often worsens with stress, but there is no specific cause or anything
unusual that the doctor can see in the colon.
Changes in Life or Routine
During pregnancy, women may be
constipated because of hormonal changes or because the heavy uterus
compresses the intestine. Aging may also affect bowel regularity because a
slower metabolism results in less intestinal activity and muscle tone. In
addition, people often become constipated when traveling because their
normal diet and daily routines are disrupted.
Abuse of Laxatives
Myths about constipation have led to a serious
abuse of laxatives. This is common among older adults who are preoccupied
with having a daily bowel movement.
Laxatives usually are not necessary and can be habit-forming. The colon
begins to rely on laxatives to bring on bowel movements. Over time,
laxatives can damage nerve cells in the colon and interfere with the
colon's natural ability to contract. For the same reason, regular use of
enemas can also lead to a loss of normal bowel function.
Ignoring the Urge to Have a Bowel Movement
People who ignore the
urge to have a bowel movement may eventually stop feeling the urge, which
can lead to constipation. Some people delay having a bowel movement
because they do not want to use toilets outside the home. Others ignore
the urge because of emotional stress or because they are too busy.
Children may postpone having a bowel movement because of stressful toilet
training or because they do not want to interrupt their play.
Diseases that cause constipation include
neurological disorders, metabolic and endocrine disorders, and systemic
conditions that affect organ systems. These disorders can slow the
movement of stool through the colon, rectum, or anus. Figure 3 lists the
diseases that cause constipation.
Diseases That Cause ConstipationNeurological
disorders that may cause constipation include:
Metabolic and endocrine
- Multiple sclerosis
- Parkinson's disease
- Chronic idiopathic intestinal pseudo-obstruction
- Spinal cord injuries.
Systemic disorders include:
- Underactive or overactive thyroid gland
Problems with the Colon and Rectum
Intestinal obstruction, scar
tissue (adhesions), diverticulosis, tumors, colorectal stricture,
Hirschsprung's disease, or cancer can compress, squeeze, or narrow the
intestine and rectum and cause constipation.
Problems with Intestinal Function (Chronic Idiopathic
Also known as functional constipation, chronic
idiopathic (of unknown origin) constipation is rare. However, some people
are chronically constipated and do not respond to standard treatment. This
chronic constipation may be related to multiple problems with hormonal
control or with nerves and muscles in the colon, rectum, or anus.
Functional constipation occurs in both children and adults and is most
common in women.
Colonic inertia and delayed transit are two types of functional
constipation caused by decreased muscle activity in the colon. These
syndromes may affect the entire colon or may be confined to the left or
lower (sigmoid) colon.
Functional constipation that stems from abnormalities in the structure
of the anus and rectum is known as anorectal dysfunction, or anismus.
These abnormalities result in an inability to relax the rectal and anal
muscles that allow stool to exit.
What Diagnostic Tests Are Used?
Most people do not need extensive testing and
can be treated with changes in diet and exercise. For example, in young
people with mild symptoms, a medical history and physical examination may
be all the doctor needs to suggest successful treatment. The tests the
doctor performs depends on the duration and severity of the constipation,
the person's age, and whether there is blood in stools, recent changes in
bowel movements, or weight loss.
The doctor may ask a patient to describe his or
her constipation, including duration of symptoms, frequency of bowel
movements, consistency of stools, presence of blood in the stool, and
toilet habits (how often and where one has bowel movements). Recording
eating habits, medication, and level of physical activity or exercise also
helps the doctor determine the cause of constipation.
A physical exam may include a digital rectal
exam with a gloved, lubricated finger to evaluate the tone of the muscle
that closes off the anus (anal sphincter) and to detect tenderness,
obstruction, or blood. In some cases, blood and thyroid tests may be
Extensive testing usually is reserved for people with severe symptoms,
for those with sudden changes in number and consistency of bowel movements
or blood in the stool, and for older adults. Because of an increased risk
of colorectal cancer in older adults, the doctor may use these tests to
rule out a diagnosis of cancer:
- Barium enema x-ray
- Sigmoidoscopy or colonoscopy
- Colorectal transit study
- Anorectal function tests.
Barium Enema X-Ray
A barium enema x-ray involves viewing the
rectum, colon, and lower part of the small intestine to locate any
problems. This part of the digestive tract is known as the bowel. This
test may show intestinal obstruction and Hirschsprung's disease, a lack of
nerves within the colon.
The night before the test, bowel cleansing, also called bowel prep, is
necessary to clear the lower digestive tract. The patient drinks 8 ounces
of a special liquid every 15 minutes for about 4 hours. This liquid
flushes out the bowel. A clean bowel is important, because even a small
amount of stool in the colon can hide details and result in an inaccurate
Because the colon does not show up well on an x-ray, the doctor fills
the organs with a barium enema, a chalky liquid to make the area visible.
Once the mixture coats the organs, x-rays are taken that reveal their
shape and condition. The patient may feel some abdominal cramping when the
barium fills the colon, but usually feels little discomfort after the
procedure. Stools may be a whitish color for a few days after the exam.
Sigmoidoscopy or Colonoscopy
An examination of the rectum and
lower colon (sigmoid) is called a sigmoidoscopy. An examination of the
rectum and entire colon is called a colonoscopy.
The night before a sigmoidoscopy, the patient usually has a liquid
dinner and takes an enema in the early morning. A light breakfast and a
cleansing enema an hour before the test may also be necessary.
To perform a sigmoidoscopy, the doctor uses a long, flexible tube with
a light on the end called a sigmoidoscope to view the rectum and lower
colon. First, the doctor examines the rectum with a gloved, lubricated
finger. Then, the sigmoidoscope is inserted through the anus into the
rectum and lower colon. The procedure may cause a mild sensation of
wanting to move the bowels and abdominal pressure. Sometimes the doctor
fills the organs with air to get a better view. The air may cause mild
To perform a colonoscopy, the doctor uses a flexible tube with a light
on the end called a colonoscope to view the entire colon. This tube is
longer than a sigmoidoscope. The same bowel cleansing used for the barium
x-ray is needed to clear the bowel of waste. The patient is lightly
sedated before the exam. During the exam, the patient lies on his or her
side and the doctor inserts the tube through the anus and rectum into the
colon. If an abnormality is seen, the doctor can use the colonoscope to
remove a small piece of tissue for examination (biopsy). The patient may
feel gassy and bloated after the procedure.
Colorectal Transit Study
This test, reserved for those with
chronic constipation, shows how well food moves through the colon. The
patient swallows capsules containing small markers, which are visible on
x-ray. The movement of the markers through the colon is monitored with
abdominal x-rays taken several times 3 to 7 days after the capsule is
swallowed. The patient follows a high-fiber diet during the course of this
Anorectal Function Tests
These tests diagnose constipation caused
by abnormal functioning of the anus or rectum (anorectal function).
Anorectal manometry evaluates anal sphincter muscle function. A catheter
or air-filled balloon inserted into the anus is slowly pulled back through
the sphincter muscle to measure muscle tone and contractions.
Defecography is an x-ray of the anorectal area that evaluates
completeness of stool elimination, identifies anorectal abnormalities, and
evaluates rectal muscle contractions and relaxation. During the exam, the
doctor fills the rectum with a soft paste that is the same consistency as
stool. The patient sits on a toilet positioned inside an x-ray machine and
then relaxes and squeezes the anus and expels the solution. The doctor
studies the x-rays for anorectal problems that occurred while the patient
emptied the paste.
Although treatment depends on the cause,
severity, and duration, in most cases dietary and lifestyle changes will
help relieve symptoms and help prevent constipation.
A diet with enough fiber (20 to 35 grams each day) helps form
soft, bulky stool. A doctor or dietitian can help plan an appropriate
diet. High-fiber foods include beans; whole grains and bran cereals; fresh
fruits; and vegetables such as asparagus, brussels sprouts, cabbage, and
carrots. For people prone to constipation, limiting foods that have little
or no fiber such as ice cream, cheese, meat, and processed foods is also
Other changes that can help treat and prevent
constipation include drinking enough water and other liquids such as fruit
and vegetable juices and clear soup, engaging in daily exercise, and
reserving enough time to have a bowel movement. In addition, the urge to
have a bowel movement should not be ignored.
Most people who are mildly constipated do not need
laxatives. However, for those who have made lifestyle changes and are
still constipated, doctors may recommend laxatives or enemas for a limited
time. These treatments can help retrain a chronically sluggish bowel. For
children, short-term treatment with laxatives, along with retraining to
establish regular bowel habits, also helps prevent constipation.
A doctor should determine when a patient needs a laxative and which
form is best. Laxatives taken by mouth are available in liquid, tablet,
gum, powder, and granule forms. They work in various ways:
- Bulk-forming laxatives generally are considered the safest but can
interfere with absorption of some medicines. These laxatives, also known
as fiber supplements, are taken with water. They absorb water in the
intestine and make the stool softer. Brand names include
Metamucil®, Citrucel®, Konsyl®, and
- Stimulants cause rhythmic muscle contractions in the intestines.
Brand names include Correctol®,
Dulcolax®, Purge®, Feen-A-Mint®,
and Senokot®. Studies suggest that
phenolphthalein, an ingredient in some stimulant laxatives, might
increase a person's risk for cancer. The Food and Drug Administration
has proposed a ban on all over-the-counter products containing
phenolphthalein. Most laxative makers have replaced or plan to replace
phenolphthalein with a safer ingredient.
- Stool softeners provide moisture to the stool and prevent
dehydration. These laxatives are often recommended after childbirth or
surgery. Products include Colace®,
Dialose®, and Surfak®.
- Lubricants grease the stool enabling it to move through the
intestine more easily. Mineral oil is the most common lubricant.
- Saline laxatives act like a sponge to draw water into the colon for
easier passage of stool. Laxatives in this group include Milk of
Magnesia®, Citrate of Magnesia®, and Haley's M-O®.
People who are dependent on laxatives need to slowly stop
using the medications. A doctor can assist in this process. In most
people, this restores the colon's natural ability to contract.
Treatment may be directed at a specific cause. For
example, the doctor may recommend discontinuing medication or performing
surgery to correct an anorectal problem such as rectal prolapse.
People with chronic constipation caused by anorectal dysfunction can
use biofeedback to retrain the muscles that control release of bowel
movements. Biofeedback involves using a sensor to monitor muscle activity
that at the same time can be displayed on a computer screen allowing for
an accurate assessment of body functions. A health care professional uses
this information to help the patient learn how to use these muscles.
Surgical removal of the colon may be an option for people with severe
symptoms caused by colonic inertia. However, the benefits of this surgery
must be weighed against possible complications, which include abdominal
pain and diarrhea.
Can Constipation Be Serious?
Sometimes constipation can lead to
complications. These complications include hemorrhoids caused by straining
to have a bowel movement or anal fissures (tears in the skin around the
anus) caused when hard stool stretches the sphincter muscle. As a result,
rectal bleeding may occur that appears as bright red streaks on the
surface of the stool. Treatment for hemorrhoids may include warm tub
baths, ice packs, and application of a cream to the affected area.
Treatment for anal fissure may include stretching the sphincter muscle or
surgical removal of tissue or skin in the affected area.
Sometimes straining causes a small amount of intestinal lining to push
out from the anal opening. This condition is known as rectal prolapse and
may lead to secretion of mucus from the anus. Usually, eliminating the
cause of the prolapse such as straining or coughing is the only treatment
necessary. Severe or chronic prolapse requires surgery to strengthen and
tighten the anal sphincter muscle or to repair the prolapsed lining.
Constipation may also cause hard stool to pack the intestine and rectum
so tightly that the normal pushing action of the colon is not enough to
expel the stool. This condition, called fecal impaction, occurs most often
in children and older adults. An impaction can be softened with mineral
oil taken by mouth and an enema. After softening the impaction, the doctor
may break up and remove part of the hardened stool by inserting one or two
fingers in the anus.
Points to Remember
- Constipation affects almost everyone at one time or another.
- Many people think they are constipated when, in fact, their bowel
movements are regular.
- The most common causes of constipation are poor diet and lack of
- Additional causes of constipation include medications, irritable
bowel syndrome, abuse of laxatives, and specific diseases.
- A medical history and physical examination may be the only
diagnostic tests needed before the doctor suggests treatment.
- In most cases, following these simple tips will help relieve
symptoms and prevent recurrence of constipation:
- Eat a well-balanced, high-fiber diet that includes beans, bran,
whole grains, fresh fruits, and vegetables.
- Drink plenty of liquids.
- Exercise regularly.
- Set aside time after breakfast or dinner for undisturbed visits to
- Do not ignore the urge to have a bowel movement.
- Understand that normal bowel habits vary.
- Whenever a significant or prolonged change in bowel habits occurs,
check with a doctor.
- Most people with mild constipation do not need laxatives. However,
doctors may recommend laxatives for a limited time for people with
International Foundation for Functional
P.O. Box 17864
Intestinal Disease Foundation
1323 Forbes Avenue, Suite
Pittsburgh, PA 15219
National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
E-mail: National Digestive
Diseases Information Clearinghouse
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
under 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. NDDIC answers inquiries; develops, reviews,
and distributes publications; and works closely with professional and
patient organizations and Government agencies to coordinate resources
about digestive diseases.
Publications produced by the clearinghouse are reviewed carefully for
scientific accuracy, content, and readability.
This e-text is not copyrighted. The clearinghouse encourages users of
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NIH Publication No. 95-2754
e-text last updated: May 2000
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