Medical Edge Newspaper Column

Numerous Options For Treating Constipation

July 22, 2007
Dear Mayo Clinic:
I struggle with constipation. My problem is not so much straining to eliminate; I just do not get the urge. And when I do, I don't eliminate completely. After two or three days of this, I start experiencing symptoms such as low energy, sleepiness, and abdominal discomfort. Then I have to resort to laxatives. What can I do to return to normal?

Answer:
You may be reassured to know that you are not alone; chronic constipation is a very common problem. With a female predominance, it affects 10 to 20 percent of all Americans and some 40 percent of people over the age of 65.

Your comments show that there are different types of constipation. Until recently, medical training largely focused on frequency of bowel movements, with the general guideline of "normal" ranging from three times per day to three times per week. But now it is increasingly being recognized that symptoms such as bloating, excessive straining, a feeling of incomplete evacuation, and not getting the urge are symptoms of constipation, as well.

Note too that the above guideline on frequency is not universally applicable; what would be abnormal for one person may be quite normal for another. So if a patient has a bowel movement once a week, say, and that has always been his or her pattern, then it is probably fine as long as obstruction has been ruled out and appropriate colon cancer screening has been done.

Clinically, constipation has either primary or secondary causes. Primary constipation -- in which the problem does not result from some other, underlying problem -- can be of three different types. The vast majority of patients (about 60 percent) have "normal-transit constipation" -- stool passes through the colon at a normal rate. People with "slow-transit constipation" (about 13 percent of patients) just don't feel an urge to have a bowel movement very often because of the sluggish passage of stool. And in "pelvic-floor dysfunction" (affecting some 25 percent of patients) stool moves through the colon but gets hung up in the rectum because of a lack of muscle coordination to empty the bowels.

Secondary constipation is attributable to a variety of other conditions, such as tumors of the colon or abdominal cavity, neurological disorders, or autoimmune diseases. Certain medications, including those used to treat high blood pressure and depression, also can cause constipation. In such cases, wherever possible, the underlying cause should be addressed.

Used in accordance with your doctor's oversight and advice, laxatives can be quite effective at treating primary constipation. Several classes of laxatives are available that differ in mechanism of action. These include bulk-forming agents such as methylcellulose (major brand name: Citrucel); stool softeners such as docusate (Colace); osmotics such as magnesium hydroxide (Milk of Magnesia), stimulants such as bisacodyl (Dulcolax), serotonergics such as tegaserod (Zelnorm), and chloride-channel activators such as lubiprostone (Amitiza).

These medications range from initial treatment options -- sufficient for relatively mild cases -- up to heavy artillery, so to speak, for the most obstinate cases. While it was thought in the past that laxative use might cause the bowels to become "lazy," current knowledge suggests that this impression may have come from the symptoms of slow-transit patients.

Laxatives can actually help patients with slow-transit constipation, though treatment with more than one agent is often required. Patients with normal-transit constipation, by contrast, are likely to find a single laxative they can use either occasionally or daily to achieve relief. Meanwhile, it is important to identify individuals with pelvic-floor dysfunction (which can be combined with normal- or slow-transit constipation). Recent studies have suggested that a course of biofeedback will help up to 70 percent of pelvic-floor dysfunction patients.

Paying attention to certain biorhythms may also be helpful -- for example, having a bowel movement after breakfast is particularly advantageous, as there may be stronger colonic contractions at that time. But recent evidence suggests that physicians' traditional recommendations of fluid, fiber, and increasing exercise, while effective for people with intermittent mild constipation, do not work well for those with chronic constipation.

-- Lucinda A. Harris, M.D., Gastroenterology, Mayo Clinic, Scottsdale, Ariz.