Diosmin

What diosmin is

Diosmin belongs to the vein medicines, also called phlebotonics. Many studies did not test pure diosmin but the micronized purified flavonoid fraction (MPFF), known as Daflon 500 mg, made of 90 percent diosmin and 10 percent hesperidin. Micronized means the active ingredient is ground into particles smaller than 2 micrometers, which is supposed to improve absorption. It is chemically related to other flavonoids such as quercetin.

In the BK-Score, human evidence stands at 7 out of 10 points. This axis rates the state of knowledge, not the substance: well studied here mainly means that the effect is small and limited to a few complaints.

How it works

In the gut, the intestinal flora splits diosmin into diosmetin, which is absorbed; according to the Austrian summary of product characteristics, the oral bioavailability of micronized diosmin is about 60 percent and the half-life of diosmetin around 31.5 hours. What has been measured in humans is an increase in venous tone: in 10 women with healthy veins, it rose from the first hour after two tablets of MPFF, measured by plethysmography (Amiel 1998).

Further pathways, such as stabilization of the capillaries and a reduced inflammatory response in the vessel wall, have been described mainly in laboratory and animal models. A plausible mechanism is not yet a clinical benefit; what counts are the controlled studies.

What the studies show

Venous insufficiency: Cochrane review 2020

Martinez-Zapata 2020 analyzed 69 randomized, double-blind, placebo-controlled studies on oral vein medicines; 56 with 7,690 participants provided usable data, 11 of them on hidrosmin and diosmin. Edema decreased slightly (relative risk 0.70), and ankle circumference fell by 4.27 mm. There was hardly any difference in quality of life (standardized mean difference −0.06; 5 studies, 1,639 participants), and no effect on ulcer healing (relative risk 0.94, low certainty). Side effects were slightly more frequent than with placebo (relative risk 1.14), mostly gastrointestinal.

Hemorrhoids: Cochrane review 2012

Perera 2012 included 24 studies; 20 of them, with 2,344 participants, compared vein medicines with a control. Itching, bleeding, bleeding after hemorrhoid surgery, discharge and overall symptoms were significantly better. For pain, the effect missed significance. The authors see a possible benefit but point to methodological limitations and call for better studies.

Venous leg ulcer: Coleridge-Smith 2005

The meta-analysis pooled 5 randomized studies with 723 patients in which MPFF was given in addition to compression and wound care. After 6 months, the chance of healing was 32 percent higher (95 % interval 3 to 70 percent), and healing took 16 instead of 21 weeks on average. The later Cochrane review found no effect on ulcer healing across all vein medicines, with low certainty of evidence.

Low-dose diosmin: Serra 2021

In a double-blind, placebo-controlled multicenter study, people with chronic venous disease of stages C2 to C4 received 450 mg daily of a diosmin preparation with improved absorption or placebo for 8 weeks; 72 completed the study. From week 4, leg edema decreased, and after 8 weeks pain and symptom scales were better than with placebo. No side effects were recorded.

Where the data stop

• Quality of life. Despite less swelling, quality of life hardly changed in the Cochrane review.
• Pure diosmin versus MPFF. Many results come from studies with MPFF or from pooled analyses of different vein medicines. What of this applies to a particular diosmin product cannot always be separated.
• Ulcer healing. The meta-analysis on MPFF found faster healing; the Cochrane review across all vein medicines found no effect.
• General vein and leg health. The studies looked at people with venous disease or hemorrhoids. For healthy people without complaints there is no evidence of benefit.

Status, approval and legal

In Austria, diosmin is approved as a medicine: Diosmin Genericon 1000 mg film-coated tablets, approved in 2023, available without prescription in pharmacies only, for complaints in chronic venous insufficiency of the legs and for acute hemorrhoid symptoms. According to the summary of product characteristics, one tablet is taken daily with a meal for venous insufficiency, and more for a short period for acute hemorrhoid symptoms.

In Germany, diosmin was on the market as a vein medicine; in 2002 the arznei-telegramm named the product Tovene, classified vein medicines such as diosmin as a “questionable therapeutic principle” and reported that the Spanish medicines agency withdrew 15 oral vein medicines, including diosmin-containing ones, from the market in the same year because of a negative benefit-risk balance. Diosmin is not on the list of prescription-only substances in the German Ordinance on Prescription-Only Medicines (AMVV). Today it is also offered as a food supplement in Germany. Whether a particular product is classified as a food or as a medicine depends, among other things, on the amount and the pharmacological effect. There are no authorized health claims for diosmin under Regulation 432/2012.

Safety

According to the Austrian summary of product characteristics, diarrhea, digestive complaints, nausea and vomiting are common, headache and dizziness rare. In healthy people, diosmin inhibits cytochrome P450 enzymes; the summary of product characteristics mentions possible changes in the pharmacokinetics of diclofenac and metronidazole. It should be avoided in pregnancy as a precaution and is not recommended during breastfeeding or under 18 years of age.

According to the summary of product characteristics, it does not work for leg swelling caused by heart, liver or kidney disease; sudden or one-sided swelling should be checked by a doctor. In the BK-Score, safety stands at 7 out of 10 points; this axis measures how well safety has been studied, not how safe the substance is. This text is information and does not replace medical advice.

Sources

• Martinez-Zapata MJ et al., Cochrane Database Syst Rev 2020 – vein medicines in chronic venous insufficiency, 69 randomized studies
• Perera N et al., Cochrane Database Syst Rev 2012 – vein medicines in hemorrhoids
• Coleridge-Smith P et al., Eur J Vasc Endovasc Surg 2005 – meta-analysis, MPFF in venous leg ulcer, 5 studies, 723 patients
• Serra R et al., Nutrients 2021 – double-blind study, low-dose diosmin in chronic venous disease over 8 weeks
• Amiel M, Barbe R, Ann Cardiol Angeiol 1998 – venous tone after Daflon 500 mg in 10 women with healthy veins
• BASG – summary of product characteristics Diosmin Genericon 1000 mg film-coated tablets (Austria, as of October 2025)
• arznei-telegramm 2002, vol. 33, no. 10, p. 107 – venotonics, diosmin (Tovene)
• German Ordinance on Prescription-Only Medicines (AMVV), Annex 1 – prescription-only substances
• Regulation (EU) No 432/2012 – list of permitted health claims made on foods