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Constipation in Adults (cont.)

What are the causes of constipation in adults?

Constipation may result from several causes including a poor diet, poor bowel habits, or problems in elimination of stool, whether physical, functional, or voluntary.

The most common causes of constipation are:

Poor diet: Eating foods rich in animal fats (dairy products, meats, and eggs) or refined sugar but low in fiber (whole grains, fruits, and vegetables).

Inadequate fluid intake: Not drinking enough water can lead to hard dry stools. Fluid is absorbed in the intestine, and people who don't drink enough water may not pass enough water into the colon to keep their stools soft.

Caffeine and alcohol: These induce increased excretion and thus urination of water. This leads to (relative) dehydration because of an increase in water absorption from the intestine. This can in turn lead to constipation when not enough fluid is retained in the stool.

Poor bowel habits: Ignoring the desire to have bowel movements may initiate a cycle of constipation.

  • After a period of time, the person may stop feeling the desire to move the bowels.
  • This leads to progressive constipation. For example, some people may avoid using public toilets or ignore going to the toilet because they are busy.

Medications: Many medications can cause constipation.

  • Antacids that contain aluminum hydroxide (Alternagel, Alu-Cap, Alu-Tab, Amphojel, Dialume) and calcium carbonate (Rolaids, Mylanta, Maalox, Tums, etc.)
  • Antispasmodic drugs
  • Antidepressants
  • Iron tablets
  • Anticonvulsant drugs
  • Diuretics (because they can work like caffeine and alcohol as mentioned previously)
  • Painkillers, narcotic-containing drugs, for example, may suppress bowel function.

Travel: Changes in lifestyle, low fluid intake, and eating fast food may cause constipation.

Irritable bowel syndrome (IBS, spastic colon): Because of changes in the bowel function, if a person has this disorder, he or she may have crampy abdominal pain, excessive gas, bloating, and constipation, sometimes alternating with diarrhea.

Laxative abuse: Habitually using laxatives will gradually produce dependency on these drugs.

  • The person may eventually require increasing amounts of laxatives to move the bowels.
  • In some instances, the bowel will become insensitive to laxatives and the person will not be able to move the bowels even with laxatives.

Pregnancy: Constipation is common during pregnancy and may be due to several factors. Some of the following conditions produce severe pain on defecation, which may trigger a reflex spasm of the anal sphincter muscle. The spasm may delay bowel movement and decrease the desire for bowel opening in order to avoid the anal pain.

  • Mechanical pressure on the bowel by the heavy womb
  • Hormonal changes during pregnancy
  • Changes in food and fluid intake
  • Anal fissure (cracks in the lining of the anus)
  • Painful hemorrhoids (piles)
  • Anal stenosis (narrow anus)

Intestinal obstruction: Mechanical compression and interference with the normal functions of the bowel may occur in the following conditions:

  • Scarring of the intestine from inflammation due to diseases such as diverticulitis or Crohn's disease (an inflammatory bowel disease)
  • Inflammatory adhesions and joining together of tissues
  • Intestinal cancers
  • Abdominal hernia, in which loops of the intestine become obstructed
  • Gallstones that have become immovably wedged in the intestine
  • Twisting of the intestine upon itself (volvulus)
  • Foreign bodies (swallowed or introduced into the intestine from the anus)
  • Intussusception refers to "telescoping of the intestine" in which one part of the intestine is drawn into another part (occurs mainly in children.)
  • Postoperative adhesions (internal scarring after previous abdominal surgery) can block the small intestine and cause the inability to pass gas or move the bowels, but relatively rarely blocks the large intestine (colon).

Mechanical problems of the anus and rectum (the bottom part of the colon) that includes the rectum pushing out of the anus (rectal prolapse) or into the vagina.

Damage to nerves within the intestine: (Spinal cord tumors, multiple sclerosis, or spinal cord injuries may produce constipation by interfering with the function of the nerves supplying the intestine.)

Connective tissue diseases: Conditions such as scleroderma and lupus

Poor-functioning of the thyroid gland: Reduced production of thyroxin, a hormone produced by the thyroid gland, can lead to hypothyroidism, and therefore can cause constipation.

Lead poisoning and other metabolic disorders

Age: Older adults are more likely to have constipation for the following reasons:

  • Poor diet and insufficient intake of fluids
  • Lack of exercise
  • Side effects of prescription drugs used to treat other conditions
  • Poor bowel habits
  • Prolonged bed rest, for example after an accident or during an illness
  • Habitual use of enemas and laxatives

It should be noted that although that this is a long list of possibly scary causes of constipation, most chronic constipation is simply from inadequate intake of dietary fiber and water, and can be managed by substantially increasing the intake of both.

Medically Reviewed by a Doctor on 6/24/2015

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