Laxatives For Constipation (cont.)
Stimulant Laxatives
Stimulant laxatives induce bowel movements by increasing the contraction of muscles in the intestines, and are effective when used on a short term basis. Examples of stimulant laxatives include aloe, cascara, senna compounds, bisacodyl, and castor oil.
Bisacodyl (Dulcolax, Correctol) is available OTC in oral pill form and as a suppository or enema. The oral form takes
6 to 10 hours to work. Bisacodyl is commonly used in cleansing the colon for
colonoscopies,
barium enemas, and intestinal surgeries. While effective for occasional constipation, bisacodyl should not be taken for more than a week, and a doctor should supervise repeated use.
Other stimulant laxatives include senna (Ex-Lax, Senokot), cascara sagrada (Nature's Remedy), and casanthranol. These laxatives are converted by the bacteria in the colon into active compounds which then stimulate the contraction of colon muscles. After taking these products orally, bowel movements occur after
8 to 24 hours. Prolonged, chronic use of these laxatives can cause the lining of the colon to become darker than normal (melanosis coli) due to the accumulation of a pigment (melanin).
Castor oil (an ingredient of Purge Concentrate) is a liquid
stimulant
laxative that works in the small intestine. It causes the
accumulation of fluid in the small intestine and promotes
evacuation
of the bowels. Castor oil should not be taken with food,
although
juice or other flavored liquids can help hide its
unpleasant taste.
This laxative works rather quickly, usually within 2 to 6 hours.
Castor oil is usually used to cleanse the colon for
surgery, barium
enema, or colonoscopy. The absorption of nutrients and
minerals by
the small intestine can be impaired by the frequent use of
castor
oil. Therefore, this medicine is not recommended for the
repeated
treatment for constipation.
Precautions
- The intensity of the action of stimulant laxatives is
dose
related. A large dose of any stimulant laxative can
produce
serious adverse effects.
- Side effects include severe cramps, excess fluid loss
and
dehydration,
blood electrolyte disturbances such as low
levels of
blood potassium, and malnutrition with chronic use.
- Chronic, long-term use of stimulant laxatives can lead
to loss of
colon function (cathartic colon). After years to decades of
frequent
use of stimulant
laxatives, the nerves of the colon slowly disappear, the
colon
muscles wither, and the colon becomes dilated.
Consequently,
constipation becomes increasingly worse and unresponsive to
laxatives.
Next: Saline Laxatives »
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