Herb & supplement monograph

Diosmin Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Diosmin interacts with medications. The heart of this page is the interaction list — every drug Diosmin is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Diosmin is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Diosmin Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Diosmin drug interaction appears low to moderate for most people, since no interaction is rated major. Every listed interaction is rated moderate, and many rest on theory about how diosmin may affect the enzymes and transporters the body uses to clear medications.

Interactions deserving the most attention

The best-documented concern is carbamazepine, a seizure medicine. A human study found diosmin raised its blood levels and slowed its clearance, which could matter for seizure control. Similar human studies showed higher levels of diclofenac, chlorzoxazone, and fexofenadine when taken after diosmin. There is also one report of serious bleeding in an older woman taking warfarin, aspirin, and diosmin together, so people on blood thinners deserve extra care even though that evidence is limited.

What the rest of the list means

The long list of interacting medications mostly comes from a few broad drug-processing pathways that diosmin may inhibit, so a medication can appear on it based on theory alone. Lab findings even conflict for one of these pathways. Only a handful of medicines have actually been studied with diosmin in people, and the observed changes were moderate, not dangerous.

Check your medications against Diosmin

Based on HelloPharmacist’s Diosmin interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Diosmin

885 medications have a known interaction with Diosmin, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Diosmin using our pharmacist-reviewed interaction data.

AI summaries are generated from our Diosmin interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Diosmin combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Diosmin affects

Every type of medication (drug category) Diosmin is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 9 drug categories Diosmin interacts with

Anticoagulant/antiplatelet DrugsCarbamazepine (tegretol)Chlorzoxazone (parafon Forte, Paraflex)Cytochrome P450 2c9 (cyp2c9) SubstratesCytochrome P450 2e1 (cyp2e1) SubstratesCytochrome P450 3a4 (cyp3a4) SubstratesDiclofenac (voltaren, Others)Fexofenadine (allegra)P-glycoprotein Substrates

Anticoagulant/Antiplatelet Drugs

Theoretically, diosmin may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
A case of spontaneous intraventricular hemorrhage has been reported for a 77-year-old female after 6 weeks of warfarin therapy, despite an international normalized ratio (INR) of only 1.8. The patient had also been taking aspirin and diosmin for several years. Experts speculate that chronic intake of diosmin predisposed the patient to spontaneous intraventricular hemorrhage by inducing chronic microcirculatory hypertension and inhibiting platelet aggregation. The presence of aspirin was also thought to play a role in this event.

Likelihood Possible Evidence D

Carbamazepine (Tegretol)

Theoretically, diosmin might reduce the effects of carbamazepine and increase the risk for convulsions.
A pharmacokinetic study in humans shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of carbamazepine 200 mg increases blood levels of carbamazepine by approximately 58% and decreases carbamazepine clearance by 42%. It also decreases the formation of carbamazepine's active metabolite. It is speculated that diosmin reduces the metabolism of carbamazepine by inhibiting cytochrome P450 3A4 (CYP3A4).

Likelihood Probable Evidence B

Chlorzoxazone (Parafon Forte, Paraflex)

Theoretically, diosmin might increase the levels and clinical effects of chlorzoxazone.
A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of chlorzoxazone 250 mg increases blood levels of chlorzoxazone by 53% and decreases chlorzoxazone clearance by 40%. It is speculated that diosmin reduces the metabolism of chlorzoxazone by inhibiting cytochrome P450 2E1 (CYP2E1).

Likelihood Probable Evidence B

Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, diosmin might inhibit the metabolism of CYP2C9 substrates.
Diclofenac is metabolized by CYP2C9 enzymes. Clinical and laboratory research shows that diosmin inhibits the metabolism of diclofenac. A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of diclofenac 100 mg increases blood levels of diclofenac and decreases diclofenac clearance.

Likelihood Possible Evidence D

Cytochrome P450 2E1 (Cyp2E1) Substrates

Theoretically, diosmin might inhibit the metabolism of CYP2E1 substrates.
Chlorzoxazone is metabolized by CYP2E1 enzymes. A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of chlorzoxazone (Paraflex 250) 250 mg increases blood levels of chlorzoxazone by 34% and decreases chlorzoxazone clearance by 40%. It is speculated that diosmin reduces the metabolism of chlorzoxazone by inhibiting CYP2E1.

Likelihood Possible Evidence D

Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, diosmin might inhibit the metabolism of CYP3A4 substrates.
Laboratory research is conflicting with respect to the effects of diosmin on CYP3A4. Some research suggests that diosmin does not affect CYP3A4 activity. However, other research suggests that diosmin alters the metabolism of carbamazepine, a CYP3A4 substrate. Laboratory and animal research show that oral administration of diosmin for 7 days prior to oral administration of carbamazepine increases plasma concentrations of carbamazepine, decreases the clearance of carbamazepine, and decreases the formation of carbamazepine's active metabolite. Additionally, pharmacokinetic research in healthy male subjects shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of carbamazepine 200 mg increases blood levels of carbamazepine by approximately 58% and decreases carbamazepine clearance by 42%. It is speculated that diosmin reduces the metabolism of carbamazepine by inhibiting CYP3A4. Diosmetin, a metabolite of diosmin, may also inhibit CYP3A4.

Likelihood Possible Evidence B

Diclofenac (Voltaren, Others)

Theoretically, diosmin might increase the levels and clinical effects of diclofenac.
Clinical and laboratory research shows that diosmin inhibits the metabolism of diclofenac. A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of diclofenac 100 mg increases blood levels of diclofenac and decreases diclofenac clearance. It is speculated that diosmin reduces the metabolism of diclofenac by inhibiting cytochrome P450 2C9 (CYP2C9).

Likelihood Probable Evidence B

Fexofenadine (Allegra)

Theoretically, diosmin might increase the levels and clinical effects of fexofenadine.
A pharmacokinetic study in humans shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of fexofenadine 120 mg increases blood levels of fexofenadine by approximately 49% and decreases the apparent oral clearance of fexofenadine by 41%. The time taken to reach maximum plasma concentration, the half-life, and the apparent renal clearance of fexofenadine are not affected. For this reason, it is speculated that diosmin alters the pharmacokinetics of fexofenadine via inhibition of P-glycoprotein in the intestine, but not in the kidney or liver.

Likelihood Probable Evidence B

P-Glycoprotein Substrates

Theoretically, diosmin might increase levels of drugs that are substrates of P-glycoprotein (P-gp).
Preliminary laboratory research suggests that diosmin inhibits P-gp. Additionally, pharmacokinetic research in healthy male subjects shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of fexofenadine 120 mg increases blood levels of fexofenadine, a P-gp substrate, by approximately 49% and decreases the apparent oral clearance of fexofenadine by 41%. The time taken to reach maximum plasma concentration, the half-life, and the apparent renal clearance of fexofenadine are not affected. For this reason, it is speculated that diosmin inhibits P-gp in the intestine, but not in the kidney or liver.

Likelihood Possible Evidence D

Monograph

Diosmin: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Diosmin is a citrus-derived flavonoid most often used for vein-related problems such as chronic venous insufficiency and hemorrhoids, and it is usually combined with a related flavonoid called hesperidin. Some studies suggest it may help relieve leg swelling and hemorrhoid symptoms, but quality varies. Talk to your pharmacist or doctor before starting it, especially if you are pregnant or breastfeeding.

Part used: A flavonoid derived from citrus fruit peels (often made from hesperidin)
Common forms: Tablets, capsules (often combined with hesperidin)

People commonly use it for

Chronic venous insufficiency
Hemorrhoids
Leg swelling and heaviness
Varicose veins
Spider veins

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated short-term, but long-term safety is less well studied.

PregnancyLikely Safe

When used orally in amounts found in foods.

Read the full pregnancy detail

BreastfeedingLikely Safe

When used orally in amounts found in foods.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Diosmin is a plant compound called a flavonoid. It is found naturally in some citrus fruits and is usually made commercially from the peels of oranges or other citrus, often by converting a related flavonoid called hesperidin.

It is most often sold as a supplement or, in some countries, as a prescription medicine for vein problems. Many products combine diosmin with hesperidin in a mixture sometimes labeled as a "micronized purified flavonoid fraction."

People most commonly take diosmin to support healthy blood flow in the legs and to ease symptoms tied to veins, such as swelling, heaviness, and hemorrhoids.

How it works

Diosmin is thought to work mainly by improving the tone and strength of vein walls and by reducing leakiness of small blood vessels. This may help blood and fluid move better and reduce swelling.

Laboratory and animal studies suggest it may also reduce inflammation, protect the lining of blood vessels, and improve lymph flow. Some research suggests it has antioxidant effects as well.

It is important to know that many of these proposed mechanisms come from laboratory and animal research, and how strongly they apply in the human body is not fully understood.

Effectiveness

Does Diosmin work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 18 uses evaluated

3 Possibly effective 15 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Chronic venous insufficiency (CVI)