Abstract— Quercitrin, a flavonoid isolated from Euphorbia hirta, shows antidiarrhoeic activity at doses of 50 mg kg−1, against castor oil- and PGE2-induced diarrhoea in mice, but not when magnesium sulphate is used as a cathartic agent. It also delays rat small intestinal transit if this is accelerated with castor oil. However, the flavonoid does not modify the fluid transport across the colonic mucosa when it is administered intraluminally, either in normal conditions or when this transport is altered by PGE2 or sodium picosulphate. However, quercetin, the aglycone of quercitrin, increases the colonic fluid absorption only in the presence of secretagogue compounds, such as PGE2 and sodium picosulphate. It is concluded that the antidiarrhoeic activity of quercitrin is due to its aglycone, quercetin, which is released by the glycoside in the intestine.