Laxatives commonly are classified into the following categories: (1) stimulant or irritant, (2) stool softeners, (3) saline, (4) bulk, and (5) lubricant. Although this classification suggests different mechanisms of action for each category, Binder and Donowitz1 have proposed that the accumulation of water and electrolytes in the intestinal lumen may be the common denominator of all laxative action.
In 1973 there were 42 US pharmaceutical firms marketing 132 over-the-counter laxative products that contained one or more of 17 different allegedly "safe, effective, active ingredients." Americans spent $241 million on laxatives in 1975.2 A Food and Drug Administration panel that reviewed the safety and effectiveness of laxatives concluded that there was widespread overuse of laxatives that tended to increase with age. It appears that need for laxatives results largely from the intake of a diet that is low in fiber content and inadequate in fluid intake, from the lack
Silva OL. The Not-So-Harmless Laxative. Arch Intern Med. 1978;138(7):1067. doi:10.1001/archinte.1978.03630320011006