The root of Turkish rhubarb, Rheum palmatum L. [Fam. Polygonaceae], has been used traditionally to improve both digestion and loss of appetite. The bitter tea is rich in tannins that increase the flow of saliva and gastric secretions and can be used as an astringent or stomachic at a low dosage to stop diarrhea (0.1-0.2g).

Formerly, the root was an important drug in many army camps, said to stop the deadly scourge of dysentry in its tracks. At a higher dosage (1.0-2.0g) the anthraquinones that it contains function as a safe and effective laxative. This is an example of a plant that can be used for opposite purposes depending upon the dosage.

The German Pharmacopoeia recommends the root against constipation and for all disorders in which defecation with a soft stool is desired, e.g. anal fissures after rectal operations. It also recommends a small dose for stomach and bowel catarrh. Today the substance is mostly used as a laxative and is a component of many choleretic drugs (a choleretic increases the flow of bile into the intestines and is recommended in cases of liver and biliary disorders that often cause constipation).

The active glycosides are hydrolyzed in the gut into their aglycones at least in part by the action of bacterial enzymes; by influencing the water and electrolyte transport in the colon, these aglycones are responsible for the laxative action.