Drug & supplement interaction

Diosmin + Mefenamic Acid

Mefenamic Acid brand name: Ponstel.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Diosmin has a moderate interaction with Mefenamic Acid. Theoretically, diosmin might inhibit the metabolism of CYP2C9 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Diosmin and Mefenamic Acid

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

Why this applies to Mefenamic Acid

Mefenamic Acid falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Diosmin interacts with.

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.
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist: your body clears mefenamic acid (Ponstel) largely through a liver enzyme called CYP2C9. Diosmin is thought to slow that same enzyme down. So in theory, pairing the two could let mefenamic acid linger a bit longer and build up, which may nudge up its usual side effects. With this NSAID that can mean stomach upset, heartburn, nausea, or in some cases stomach irritation or bleeding, plus extra strain on the kidneys.

I want to be honest about the strength here. This is a theoretical concern based on how the drug is processed and on a study using a related NSAID, not direct proof with mefenamic acid itself. It's worth a quick chat with your pharmacist or doctor, but nothing to panic over.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Rajnarayana K, Venkatesham A, Krishna DR. Bioavailability of diclofenac sodium after pretreatment with diosmin in healthy volunteers. Drug Metabol Drug Interact. 2007;22(2-3):165-74. PubMed
  2. Poór M, Boda G, Mohos V, et al. Pharmacokinetic interaction of diosmetin and silibinin with other drugs: Inhibition of CYP2C9-mediated biotransformation and displacement from serum albumin. Biomed Pharmacother. 2018;102:912-921. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Diosmin Also Interacts With Other Medications

Diosmin has 883 moderate known drug interactions in our database — the Mefenamic Acid one above is one of them. If you take anything else, check it against the full list below.

Moderate 883 No known interaction 1,947 (incl. Mefenamic Acid)
Taking anything else?

Check Another of Your Medications Against Diosmin

Covers the 2,830 medications we’ve checked against Diosmin. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Mefenamic Acid

This page covers Diosmin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mefenamic Acid page lists 118 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Siberian Cocklebur (major) and Wine (major).

By severity: 5 major · 86 moderate · 27 minor.

From our pharmacist’s overview on the Mefenamic Acid page

“Mefenamic acid (Ponstel), an NSAID mostly used for menstrual cramps and short-term pain, has a supplement list that earns genuine caution, and the five major-rated entries are where to start. Beer and wine are two of them, because alcohol plus any NSAID raises the risk of stomach and intestinal bleeding.”

Reviewed by 2 · Jul 18, 2026

Open the Mefenamic Acid interaction page

One more smart check

Taking Diosmin as Part of a Dietary Supplement Product? Check It for Interactions

We hold 121 real supplement products containing Diosmin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Diosmin. Your product may carry other ingredients that interact with Mefenamic Acid too, on top of Diosmin — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Diosmin and Mefenamic Acid Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Diosmin
Top half

#384 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Mefenamic Acid
Top half

#1,246 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Diosmin

What is Diosmin?

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

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.

Read the full Diosmin monograph & all interactions
Medication

About Mefenamic Acid

What Is Mefenamic Acid Used For?

Brand name: Ponstel

Mefenamic acid capsules are approved to manage mild to moderate pain in adults and adolescents 14 years of age and older, but only for short-term use — no longer than 7 days.

They are also approved to treat primary dysmenorrhea (painful menstrual periods), started at the onset of bleeding and associated symptoms.

See full Mefenamic Acid drug information
Keep checking

Other Drugs & Diosmin

Browse every other medication we’ve checked against Diosmin — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
883Moderate
0Minor
1,946No known interaction
883 Moderate 1,946 No interaction
Moderate

883 interactions

Showing 60 of 883 moderate interactions — see all 883 on the Diosmin page.

No interaction 1,946 drugs checked — show the list

We also checked Diosmin against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,946 medications checked with no known interaction — see the full Diosmin list.

See the full Diosmin interactions page
See every supplement checked against Mefenamic Acid, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Diosmin monograph › Uses, safety, and every drug interaction in one place Mefenamic Acid supplement interactions › Every supplement checked against Mefenamic Acid, ranked by severity Mefenamic Acid drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Diosmin and Mefenamic Acid Together: Common Questions

Can you take Diosmin with Mefenamic Acid?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Diosmin and Mefenamic Acid interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Mefenamic Acid and Diosmin?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.