Diosmin is a flavone indicated for the treatment of venous disease i.e., chronic venous insufficiency (CVI) including spider and varicose veins, leg swelling (edema), stasis dermatitis and venous ulcers. Diosmin is also used as a stand-alone or surgical adjunctive therapy in hemorrhoidal disease. There are extensive clinical trials that show diosmin improves all stages of venous disease including venous ulcers and improves quality of life. Diosmin prolongs the vasoconstrictor effect of norepinephrine on the vein wall, increasing venous tone, and therefore reducing venous capacitance, distensibility, and stasis. This increases the venous return and reduces venous hyperpressure present in patients suffering from CVI. Diosmin improves lymphatic drainage by increasing the frequency and intensity of lymphatic contractions, and by increasing the total number of functional lymphatic capillaries. Furthermore, diosmin with hesperidine decreases the diameter of lymphatic capillaries and the intralymphatic pressure. Diosmin reduces the expression of endothelial adhesion molecules (ICAM1, VCAM1), and inhibits the adhesion, migration, and activation of leukocytes at the capillary level. This leads to a reduction in the release of inflammatory mediators, principally oxygen free radicals, and prostaglandins (PGE2, PGF2a). Diosmin is currently a prescription medication in some European countries (under the Dio-PP, Venotec, Daflon etc. tradenames), and is sold as a nutritional supplement in the United States.