The end result is that there is much more water in the stool, keeping it very soft, and causing it to move through the intestine more quickly. In high doses, magnesium salts often produce diarrhea. Sennokot and Fletcher's Castoria - these laxatives contain the natural plant derivative senna. Senna stimulates the intestine to secrete salt and water so that there is much more water in the stool, keeping it very soft, and causing it to move through the intestine more quickly. In some children, high doses of senna cause cramps and diarrhea.
Mineral oil is a non-absorbable oil that is digested by bacteria living in the large intestine.
Some of the by-products of this digestion stimulate the intestine to secrete salt and water. This results in there being much more water in the stool, keeping it very soft, and causing it to move through the intestine more quickly. When taking high doses of mineral oil, many children will experience some orange seepage as well as some itching at their anus. Fiber laxatives contain complex sugars that are not digested or absorbed in the intestine. As a result, the sugars remain in the intestine and keep water with them.