c. Cathartics should NOT be used when the client has an undiagnosed intestinal
pain such as cramps, nausea, or vomiting; a cathartic may cause an inflamed appendix
to rupture. Nor should cathartics be used when the GI tract is mechanically obstructed;
the intestine may rupture. Pregnant clients should ordinarily not be given cathartics.
2-29. STIMULANT (IRRITANT) CATHARTICS
Stimulant cathartics function either by irritating the mucous membranes of the
intestines or directly stimulating the nerves and muscles concerned with bowel
movement. Since individual reactions to stimulant cathartics vary, the usual dose may
in some clients cause excessively severe effects, including diarrhea and intestinal
cramps, and in other clients have no effectiveness.
a. Aromatic cascara fluidextract is a mild, effective stimulant laxative that takes
about 8 hours to take effect, since it acts on the colon rather than the small intestines.
Another stimulant laxative containing cascara sagrada is cascara tablets. After about 8
hours, these preparations produce a single evacuation of the bowels.
b. Bisacodyl (Dulcolax) is another stimulant cathartic that acts primarily on the
colon. Bisacodyl cleanses the bowel thoroughly enough to obviate the need for an
c. The one stimulant cathartic that stimulates the small intestine is castor oil.
Castor oil is not used routinely but only when prompt, thorough evacuation of the
bowels is desired, such as for a special examination.
2-30. SALINE CATHARTICS
Saline cathartics, salts which draw water into the GI tract and thereby increase
the bulk of the intestinal contents, usually take about 3 to 6 hours to produce a bowel
evacuation, which is watery or fluid-like. Saline cathartics, unless administered with
sufficient amounts of water, tend to dehydrate the body and are sometimes used for this
purpose alone. In order to avoid magnesium poisoning, cathartics containing
magnesium compounds must never be given to clients with impaired kidney function.
Cathartics containing sodium compounds should not be administered to clients with
congestive heart disease.
a. A mild saline cathartic is milk of magnesia, which contains magnesium
hydroxide and which is also used as an antacid. The cathartic dose is 15-30 ml.
b. Magnesium sulfate (epsom salt) is a widely used saline cathartic. Its main
disadvantage is its bitter taste, which can be masked to some extent by mixing with ice
water or orange juice. The usual dose is 15 grams.