Diosmin is a flavonoid compound derived from citrus fruits and is commonly used in the management of chronic venous insufficiency and related conditions, including edema (the accumulation of fluid in tissues). The rationale for its use is based on its pharmacological effects, which include venotonic (increasing venous tone), vasoprotective, and anti-inflammatory properties. Several randomized controlled trials and systematic reviews have evaluated the efficacy of diosmin (often in combination with hesperidin) for reducing leg edema, particularly in patients with chronic venous disease or varicose veins.

Clinical studies, such as those summarized in a 2017 Cochrane Review, indicate that diosmin can significantly reduce leg volume and improve symptoms of edema compared to placebo. The European Society for Vascular Surgery and other guidelines mention flavonoids, including diosmin, as an adjunctive treatment for venous symptoms and edema. However, while the evidence is generally positive, most trials have methodological limitations, such as small sample sizes and potential bias. Thus, the overall strength of evidence is moderate.

In summary, the use of diosmin for edema is scientifically supported, particularly for edema associated with chronic venous insufficiency. However, more high-quality research is needed to confirm its efficacy and long-term safety.