Diosmin is a flavonoid compound primarily found in citrus fruits and is commonly used in combination with hesperidin for the treatment of chronic venous insufficiency (CVI) and varicose veins. Its use is supported by a substantial body of scientific evidence. Multiple randomized controlled trials and meta-analyses have demonstrated that diosmin, especially in micronized purified flavonoid fraction (MPFF) formulations, can significantly reduce symptoms associated with varicose veins, such as leg swelling, pain, heaviness, and cramps. The proposed mechanisms of action include improvement of venous tone, reduction of capillary permeability, enhancement of lymphatic drainage, and anti-inflammatory effects.

A 2014 Cochrane systematic review concluded that MPFF (which contains diosmin and hesperidin) improves leg and ankle swelling and may also reduce symptoms like pain and heaviness in people with CVI. The European Society for Vascular Surgery and other vascular medicine guidelines recognize MPFF as an evidence-based treatment option for symptomatic relief in varicose veins and CVI. While the quality of individual studies varies, the overall evidence base is robust enough that diosmin is approved for these uses in several European and Latin American countries. However, diosmin is not considered a cure; it is used primarily to manage symptoms and improve quality of life, often as an adjunct to other therapies such as compression stockings or surgery.