This type of laxative works by drawing water into the colon, which softens the stool and makes it easier to pass.
Laxatives such as Epsom salts work in a way similar to bulk-forming
laxatives in that they attract water to the colon to soften
and swell the stool. Osmotic agents, however, draw water
not only from within the colon
itself, but also from surrounding body fluids. As a result,
it is very important that if using these types of laxatives
plenty of liquids (water) must be taken to balance out and
replace any loss of fluid from inside the body.
Because some of the sodium salts contained in osmotic laxatives may
be absorbed into the system, it is advisable that people
with high blood pressure, weak heart muscles or kidney disease,
check with their GP before using them.
Sugar and alcohol-based laxatives such as Lactulose and lactitol
ferment in the intestine, forming acids that stimulate the
bowel muscles. They
can take three days to work the first time they are used,
and may produce painful intestinal gas.
