What is the real danger of using herbal laxatives long term?  I'm
talking about the likes of Cascara Segrada, Senna, etc.  I've heard
they can "damage" the colon, but I've also heard that's a farce.  They
are just herbs, and they stimulate the colon the same way something
like prunes would, I believe.  What's the truth?

Keep in mind that the fact that a product is herbal says nothing
whatsoever about its safety. Some of the most deadly poisons known to
man are "herbal."

<http://womynweb.com/cascara.htm>

"Long-term use leads to losses of electrolytes, in particular
K(&plus;)ions, and as a result of this to hyperaldosteronism,
inhibition of intestinal motility and enhancement of the effect of
cardioactive steroids; in rare cases also to heart arrhythmias,
nephropathies, edemas and accelerated bone deterioration."

<http://www.wholehealthmd.com/refshelf/substances_view/1,1525,10013,00.html>
"Long-term use of any laxative, including cascara sagrada, can lead to
a potassium deficiency. A low potassium level in the body can
potentiate (increase) the effect of digitalis drugs and cause
dangerous heart beat irregularities. For this reason, you should avoid
using cascara with other drugs that lower potassium, such as diuretics
("water pills") and corticosteroids."

<http://www.chiroweb.com/find/tellmeabout/cascara_sag.html>
"Prolonged use of cascara sagrada may result in a variety of
side-effects, including spastic colon, heart arrythmias, nepropathy
and edema. Long-term use can lead to loss of electrolytes,
particularly potassium ions. Conditions such as hematuria, muscle
weakness and albuminuria may result from long-term cascara use. In
addition, cascara may interact negatively with a number of
pharmaceuticals, including thiazide diuretics, corticoadrenal
steroids, antiarrythmics, digitalis and indomethacin. Cascara sagrada
should not be taken by patients with intestinal obstructions, colitis,
Crohn?s disease, appendicitis or unknown abdominal pain. It should not
be administered to children under the age of 12."