Normally, people have bowel movements at fairly regular intervals, and stool passes out of the body easily without much straining or discomfort. Although the normal frequency of bowel movements varies from person to person, about 95% of healthy adults have a pattern that ranges from three times a day to three times a week.
In constipation, bowel movements either occur less often than expected or the stool is hard, dry and difficult to pass. Most of the time, constipation is not related to an illness or digestive disorder. Instead, the problem is caused by diet, lifestyle, medications or some other factor that hardens the stool or interferes with the stool's ability to pass comfortably. Some common triggers of constipation in adults include:
A diet low in fiber —You need about 25 grams to 30 grams of fiber every day to soften the stool and encourage proper bowel function. Most American diets contain less than half that amount.
Inadequate fluid intake — To help prevent stools from becoming dry and hard, your daily diet should include at least six to eight "servings" of water. "Servings" can include full glasses of milk, juice and other beverages, but you also can count the water content in fruits, soups, stews and solid foods.
A sedentary lifestyle — Because regular exercise is necessary to promote normal muscle contractions in the bowel wall, having a sedentary job or rarely exercising puts you at high risk of constipation.
Ignoring the urge to defecate — If you have your bowel movements right after you feel an urge to defecate, this reinforces a normal nerve reflex that helps you to pass stool easily. Sometimes, because of a busy schedule or limited access to restrooms, a person ignores the urge to defecate. If you repeatedly postpone bathroom trips until a more convenient time, this can lead to constipation problems.
Travel and scheduling factors — Travel can promote constipation by changing your diet, interfering with the normal timing of your meals, and limiting your access to restrooms.
Laxative overuse — Long-term, regular use of laxatives can teach your bowel to rely on these medicines for help with bowel movements. Eventually, a laxative habit can contribute to your constipation, making you dependent upon continued laxative use.
A side effect of medications — Constipation is a side effect of many prescription and nonprescription medications. Common problem medicines include iron supplements and vitamins that contain iron; calcium supplements; antacids that contain aluminum; antidepressants; drugs to treat schizophrenia or hallucinations; narcotic pain killers; general anesthesia; diuretics; muscle relaxants; and certain prescription drugs used to treat seizure disorders, Parkinson's disease, overactive bladder, and hypertension.
Local pain or discomfort around the anus — An anal fissure or hemorrhoids can make bowel movements painful or uncomfortable. (An anal fissure is a small tear in the skin around the anus, and a hemorrhoid is a bulge from a vein in the anus.) To avoid pain, a person with one of these problems sometimes resists the urge to defecate. This can cause symptoms of constipation.
Less often, constipation may be a symptom of an illness or condition that affects the digestive tract, the brain or the spinal cord. Some examples include irritable bowel syndrome, intestinal obstruction, diverticulitis, colorectal cancer, hypothyroidism, abnormally high blood calcium levels (hypercalcemia), multiple sclerosis, Parkinson's disease and spinal cord injury. Constipation can also be caused by abnormal positioning of pelvic organs (for example, sagging of the uterus, called "uterine prolapse"), or abnormal contraction of muscles in the pelvis.
Constipation is a very common problem that affects at least 80% of people at some time during their lives. In the United States, treatment for constipation accounts for more than 2.5 million visits to doctors' offices each year, with at least $800 million spent annually for laxatives. Although adults of all ages can suffer from constipation, the risk of this problem increases dramatically after age 65 in both men and women.
Occasionally, long-term constipation develops into fecal impaction, which is a blocked colon from a mass of stool that can't be moved by colon contractions. Fecal impaction can cause pain and vomiting, and a person with fecal impaction may require emergency treatment or hospitalization. Fecal impaction is a fairly common complication of long-term constipation in the elderly and bedridden, occurring in about 30% of all nursing home residents.