National Digestive Diseases (NIH)
Who gets constipated?
What causes constipation?
What diagnostic tests are used?
How is constipation treated?
Can constipation be serious?
Hope Through Research
Points to Remember
For More Information
The lower digestive tract
Constipation 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
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. Also, 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
its causes, prevention, and treatment will help most people find relief.
Who gets constipated?
According to the 1996 National Health Interview Survey, about 3 million people in the United
States have frequent constipation. Those reporting constipation most often are women and
adults age 65 and over. Pregnant women may have constipation, and it is a common problem
following childbirth or surgery.
Constipation is one of the most common gastrointestinal complaints in the United States,
resulting in about 2 million doctor visits annually. However, most people treat themselves
without seeking medical help, as is evident from the millions of dollars 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 the colon, it 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 or if
the colon’s muscle contractions are slow or sluggish, causing the stool to move through the
colon too slowly. Common causes of constipation are
– not enough fiber in the diet
– not enough liquids
– lack of exercise
– irritable bowel syndrome
– changes in life or routine such as pregnancy, older age, and travel
– abuse of laxatives
– ignoring the urge to have a bowel movement
– specific diseases such as stroke (by far the most common)
– problems with the colon and rectum
– problems with intestinal function (chronic idiopathic constipation)
– not Enough Fiber in the Diet
– 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—both 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 through the intestines almost unchanged. The bulk
and soft texture of fiber help prevent hard, dry stools that are difficult to pass.
According to the National Center for Health Statistics, Americans eat an average of 5 to 14
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 from which
the natural fiber has been removed.
A low-fiber diet also plays a key role in constipation among older adults, who may lose
interest in eating and choose convenience foods low in fiber. In addition, difficulties with
chewing or swallowing may force older people to eat soft foods that are processed and low in
*National Center for Health Statistics. Dietary Intake of Macronutrients, Micronutrients,
and Other Dietary Constituents: United States, 1988–94. Vital and Health Statistics, Series
11, number 245. July 2002.
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. Liquids that contain
caffeine, like coffee and cola drinks, and alcohol have a dehydrating effect.
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.
Some medications can cause constipation. They include
– pain medications (especially narcotics)
– antacids that contain aluminum and calcium
– blood pressure medications (calcium channel blockers)
– antiparkinson drugs
– iron supplements
– 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
Abuse of Laxatives
Myths about constipation have led to a serious abuse of laxatives. This is common among
people 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.
Several kinds of diseases can cause constipation:
– multiple sclerosis
– Parkinson’s disease
– chronic idiopathic intestinal pseudo-obstruction
– spinal cord injuries
– Metabolic and endocrine conditions
– underactive or overactive thyroid gland
– Systemic disorders
– 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 Constipation)
Some people have chronic constipation that does not respond to standard treatment. This rare
condition, known as idiopathic (of unknown origin) chronic constipation may be related to
problems with intestinal function such as 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 lower or 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 with constipation 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 depend on the duration and severity of the constipation, the person’s
age, and whether blood in stools, recent changes in bowel movements, or weight loss have
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). A record of eating
habits, medication, and level of physical activity or exercise will also help the doctor
determine the cause of constipation.
The clinical definition of constipation is any two of the following symptoms for at least 12
weeks (not necessarily consecutive) in the previous 12 months:
– straining during bowel movements
– lumpy or hard stool
– sensation of incomplete evacuation
– sensation of anorectal blockage/obstruction
– fewer than three bowel movements per week
A physical exam may include a 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 necessary to look for
thyroid disease and serum calcium or to rule out inflammatory, neoplastic, metabolic, and
other systemic disorders.
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. Additional tests that may be used to evaluate constipation include
– colorectal transit study
– anorectal function tests Because of an increased risk of colorectal cancer in older adults, the doctor may use test to rule out a diagnosis of cancer, including
– barium enema x ray
– sigmoidoscopy or colonoscopy
– 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 that are visible on an x ray. The movement of the markers through the colon
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 test.
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. For this test, 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 to expel the paste. The doctor studies the x rays for
anorectal problems that occurred as the paste was expelled.
Barium enema x ray.This exam 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 a special liquid to flush 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 incomplete exam.
Because the colon does not show up well on x rays, the doctor fills it with barium, a chalky
liquid that makes the area visible. Once the mixture coats the inside of colon and rectum, 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 (sigmoid) colon is
called a sigmoidoscopy. An examination of the rectum and entire colon is called a
The patient usually has a liquid dinner the night before a sigmoidoscopy and takes an enema
early the next 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 colon with air to get
a better view. The air may cause mild cramping.
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
How is constipation treated?
Although treatment depends on the cause, severity, and duration, in most cases dietary and
lifestyle changes will help relieve symptoms of constipation and help prevent it.
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 important.
Other changes that can help treat and prevent constipation include drinking enough water and
other liquids such as fruit and vegetable juices and clear soups, 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 diet and 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
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 Serutan.
Stimulants cause rhythmic muscle contractions in the intestines. Brand names include
Correctol, Dulcolax, Purge, 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 and Surfak.
Lubricants grease the stool enabling it to move through the intestine more easily. Mineral
oil is the most common example.
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 and Haley’s M-O.
People who are dependent on laxatives need to slowly stop using them. 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
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, appearing as bright red streaks on the surface of the stool. Treatment for
hemorrhoids may include warm tub baths, ice packs, and application of a special 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, known as rectal prolapse, 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 by an enema. After softening the impaction, the
doctor may break up and remove part of the hardened stool by inserting one or two fingers
into the anus.
Hope Through Research
NIDDK’s Division of Digestive Diseases and Nutrition supports basic and clinical research
into gastrointestinal conditions, including constipation. Among other areas, researchers are
studying the anatomical and physiological characteristics of rectoanal motility and the use
of new medications and behavioral techniques, such as biofeedback, to treat constipation.
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 exercise.
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
– 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 the toilet.
– 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 chronic constipation