Rutin is a plant pigment (flavonoid) that is found in certain fruits and vegetables. Rutin is used to make medicine. The major sources of rutin for medical use include buckwheat, Japanese pagoda tree, and Eucalyptus macrorhyncha. Other sources of rutin include the leaves of several species of eucalyptus, lime tree flowers, elder flowers, hawthorn leaves and flowers, rue, St. John's Wort, Ginkgo biloba, apples, and other fruits and vegetables.Some people believe that rutin can strengthen blood vessels, so they use it for varicose veins, internal bleeding, hemorrhoids, and to prevent strokes due to broken veins or arteries (hemorrhagic strokes). Rutin is also used to prevent a side effect of cance treatment called mucositis. This is a painful condition marked by swelling and ulcer formation in the mouth or lining of the digestive tract.In combination with the proteins trypsin and bromelain, rutin is also used for osteoarthritis.