Rutin is a yellow crystalline flavonol glycoside (C 27 H 30 O 16 ) that occurs in various plants (rue, tobacco, buckwheat, etc.). Upon hydrolysis (a chemical reaction that uses water to break down a compound), rutin yields quercetin and rutinose. Rutin is used in many countries as a vasoprotectant and is an ingredient in numerous multivitamin preparations and herbal remedies. The rutosides are naturally occurring flavonoids that have documented effects on capillary permeability and edema (swelling) and have been used for the treatment of disorders of the venous and microcirculatory systems. There is some evidence for the use of rutin for chronic venous insufficiency, edema, hemorrhoids, microangiopathy (disease of small blood vessels), varicosis and venous disorders. Well presented clinical trials are required in these fields before solid recommendations can be made. Formulations, mainly consisting of the trihydroxyethyl derivative of rutin, are used in Europe, Mexico and other Latin American countries for the treatment of such venous disorders as varicose veins and hemorrhoids. The generic name for these formulations is troxerutin. Troxerutin has been widely used in Europe since the mid-1960s.