Causes
When food leaves the stomach, it's still a partly digested mush. Your
body recuperates valuable fluid from it while it's moved down the colon
(large intestine). This transforms it into normal feces. The longer it stays
in the colon, the dryer it gets. That makes it harder.
Obviously, the quantity also increases if you wait to go to the toilet. A large,
hard stool can be painful and difficult to pass. This can make people, especially
children, reluctant to go, creating a vicious cycle. It's the common pattern
of chronic constipation in children. It often begins when they start school.
Many young children avoid the school toilets and end up waiting too long.
Chronic constipation can last for months or years. It's usually caused
by poor diet, by some other disease, or by regularly ignoring the urge to go
to the toilet. Low-fiber diets and insufficient water intake are the leading
causes of constipation.
While most otherwise healthy people will occasionally experience constipation,
certain diseases or conditions can also cause it:
- bowel obstructions, such as a tumor or benign growth
- chronic kidney failure
- hypothyroidism
- irritable bowel syndrome
- neurogenic disorders such as Parkinson's disease, multiple sclerosis, or
spinal cord injury
- rectal or colon cancer
Acute constipation starts suddenly and lasts a few days. It can be caused
by a blockage, prolonged inactivity, medication, dehydration, or missing a bowel
movement. Pregnant women can develop constipation when the womb presses on the
intestine. Sometimes, general anesthetic affects the bowel muscles for a few
days after surgery. Lead poisoning and swallowing indigestible objects are other
occasional causes.
All of the following medications can slow the passage of feces through the intestine,
provoking acute constipation:
- anticonvulsants used for epilepsy
- antidepressants
- diuretics
- heart medications such as calcium-channel blockers
- iron supplements
- pain medications such as codeine and morphine
- some cough and cold medications containing dextromethorphan
- some antacids
Over-use of laxatives eventually makes the bowels less sensitive to the need
to eliminate feces and can cause chronic constipation. The bowels become dependent
on laxatives to work, and this can lead to bowel distension and a condition
called melanosis coli.
People who are bedridden can develop severe acute blockages called fecal
impaction. These may have to be removed by your doctor.