The fastest acting laxatives on the market as of 2015 are stimulant laxatives, according to WebMD. Stimulant laxatives stimulate the intestinal lining and speed up the passage of stool through the colon. This type of laxative also increases the water level in the stool to make it easier to pass.
Some of the most popular stimulant laxatives include Feen-a-Mint, Dulcolax, Correctol, Senokot and Ex-Lax, notes WebMD. Prunes, or dried plums, also act as colonic stimulants.
Stimulant laxatives should not be used regularly or daily, warns WebMD. Daily use may weaken the natural ability of the body to expel waste, causing dependency on laxatives.