How the Bowel Works

The bowel is divided into the small and large intestine. The small intestine begins at the “exit” of the stomach, and leads into the large intestine. Its purpose is to squeeze food along its length, absorbing nutrients as it does so.

The large intestine is far wider in diameter than the small intestine. When doctors refer to bowel problems, they are usually referring to conditions that affect the large intestine such as diarrhea and constipation.

The large intestine is often called the colon. It ends at the rectum, which forms the last few inches of the digestive tract, before reaching the anal opening. The colon and rectum continue to absorb nutrients from food. They also contain colonies of “healthy” bacteria that help break down undigested food matter (feces). One of the functions of the colon is to absorb water from the feces - the longer the feces remains in the colon, the more water is absorbed.

What is Constipation?

For as long as fecal matter, or stool, remains in the colon, the colon draws water from it. The more time the stool remains, it becomes drier, harder - and more difficult to pass. We call this problem “constipation,” a word derived from the Latin constipare meaning to press or crowd together. Conversely, the less time the stool remains in the colon, the less water is absorbed, resulting in diarrhea.

Most medications and other constipation relievers (laxatives) work by speeding up the passage of fecal matter through the large bowel.

How Laxatives Work

Laxatives work in two primary ways. Some contain ingredients that hasten or increase the natural squeezing action of the colon, pushing the stool out faster, and others bulk up the stool itself by holding water. The colon finds the larger stool easier to move along, and so expels it more expediently.

Some laxatives contain a stool-softening agent to make the passage of a hard stool more comfortable. This is particularly helpful if you are taking, or have recently taken certain drugs such as codeine, which slow down the natural squeezing motions of the intestines, significantly slowing down the passage of feces.

Who Gets Constipation?

People of all ages and both sexes can experience constipation. However, certain circumstances can increase the likelihood of experiencing the condition. These include advancing age, pregnancy, travelling, surgery, and taking certain medications including: antacids containing aluminum and calcium, antidepressants, antihypertensives, drugs for Parkinson’s disease, calcium-channel blockers, cough suppressants containing codeine, diuretics, NSAIDs and opioid analgesics (codeine, fentanyl, morphine, oxycodone). Some nutritional supplements may also cause constipation, including products that contain calcium or iron.

Preventing Constipation

You can help prevent constipation by following these tips:

• Drink 8 - 10 glasses of caffeine-free fluids a day, preferably water.
• Make sure your diet contains plenty of fibre from whole grains and cereals, fruits and vegetables.
• Get regular exercise. Walking is particularly good for stimulating lazy bowels.

Your Pharmacist Says:
If constipation is not relieved by lifestyle measures or short-term use of laxatives, you should schedule an appointment with your doctor to rule out any serious health condition.

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