Common causes of constipation

Many factors can dispose a person to constipation. Some can easily be prevented by changing habits and lifestyle, but often the reason(s) are not so obvious.

Following are the more common causes of constipation:

Lack of exercise. People who exercise regularly generally don't develop constipation. Basically, the colon responds to activity. Good muscle tone in general is important for regular bowel movements. The abdominal wall muscles and the diaphragm all play a crucial role in the process of defecation. If these muscles are weak, they're not going to be able to do the job as well. But exercise is not a cure-all. Increasing exercise to improve constipation may be more effective in older people, who tend to be more sedentary, than in younger people.

Opioids. The digestive tract has receptors for opioids, and constipation can occur (or worsen) when people take opioid pain medications. Opioid-induced constipation occurs in roughly 90% of cancer patients taking opioids for pain and 40% of people taking opioids for chronic noncancer pain.

Other medications. Constipation is a side effect of many prescription and over-the-counter drugs. These include antacids that contain aluminum, antispasmodics, antidepressants, tranquilizers and sedatives, bismuth salts, iron supplements, diuretics, anticholinergics, calcium-channel blockers, and anticonvulsants.

Irritable bowel syndrome (IBS). Some people who suffer from IBS have sluggish bowel movements, straining during bowel movements, and abdominal discomfort. Constipation may be the predominant symptom, or it may alternate with diarrhea. Cramping, gas, and bloating are also common.

Over use of laxatives. Laxatives are sometimes used inappropriately, for example, by people suffering from anorexia nervosa or bulimia. But for people with long-term constipation, the extended use of laxatives may be a reasonable solution. In the past, long-term use of some laxatives was thought to damage nerve cells in the colon and interfere with the colon's innate ability to contract. However, newer formulations of laxatives have made this outcome less common.

Changes in life or routine. Traveling can give some people problems because it disrupts normal diet and daily routines. Aging often affects regularity by reducing intestinal activity and muscle tone. Pregnancy may cause women to become constipated because of hormonal changes or because the enlarged uterus pushes on the intestine.

Ignoring the urge. If you have to go, go. If you hold in a bowel movement, for whatever reason, you may be inviting a bout of constipation. People who repeatedly ignore the urge to move their bowels may eventually stop feeling the urge.

Not enough fiber and fluids in the diet. A diet too low in fiber and fluids and too high in fats can con-tribute to constipation. Fiber absorbs water and causes stools to be larger, softer, and easier to pass. Increasing fiber intake helps cure constipation in many people, but those with more severe constipation sometimes find that increasing fiber makes their constipation worse and leads to gassiness and discomfort.

Other causes. Diseases that can cause constipation include neurological disorders, such as Parkinson's disease, spinal cord injury, stroke, or multiple sclerosis; metabolic and endocrine disorders, such as hypothyroidism, diabetes, or chronic kidney disease; bowel cancer; and diverticulitis. A number of systemic conditions, like scleroderma, can also cause constipation. In addition, intestinal obstructions, caused by scar tissue (adhesions) from past surgery or strictures of the colon or rectum, can compress, squeeze, or narrow the intestine and rectum, causing constipation.

For more on treating constipation and other gastrointestinal conditions, read The Sensitive Gut, a Special Health Report from Harvard Medical School.

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