Causes of Constipation
Article provided by the National Digestive Diseases Information
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
The Common Causes of Constipation
Common causes of constipation are
Causes of Constipation: Not Enough Fiber in the Diet
- 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
- abuse of laxatives
- ignoring the urge to have a bowel movement
- stroke (by far the most common)
- 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--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 fiber.
*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.
Causes of Constipation: 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.
Causes of Constipation: 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.
Causes of Constipation: Medications
Some medications can cause constipation. They include
Causes of Constipation: Irritable Bowel Syndrome (IBS)
- pain medications (especially narcotics)
- antacids that contain aluminum and calcium
- blood pressure medications (calcium channel blockers)
- antiparkinson drugs
- iron supplements
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.
Causes of Constipation: 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.
Causes of Constipation: 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.
Causes of Constipation: Ignoring the Urge to Have a Bowel
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.
Causes of Constipation: Specific Diseases
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:
Causes of Constipation: Neurological disorders
Causes of Constipation: Metabolic and endocrine conditions
- multiple sclerosis
- Parkinson's disease
- chronic idiopathic intestinal pseudo-obstruction
- spinal cord injuries
Causes of Constipation: Systemic disorders
- underactive or overactive thyroid gland
Causes of Constipation: 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
Causes of 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
Additional Constipation Information
Causes of Constipation
Treatment of Constipation