Drug & supplement interaction

Indole-3-carbinol + Diclofenac

Diclofenac brand name: Zorvolex.

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

Indole-3-carbinol has a moderate interaction with Diclofenac. Theoretically, indole-3-carbinol might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Indole-3-carbinol and Diclofenac

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

Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

Why this applies to Diclofenac

Diclofenac falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Indole-3-carbinol interacts with.

Theoretically, indole-3-carbinol might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.
In vitro research shows that indole-3-carbinol inhibits platelet aggregation.
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 of it. Diclofenac is an NSAID, and like other NSAIDs it already nudges up bleeding risk a little by affecting how your platelets clump together to form clots. Indole-3-carbinol may do something similar, so stacking the two could theoretically make bleeding or bruising a bit more likely. You might notice things like easier bruising, nosebleeds, or stomach upset that lasts.

I want to be straight with you though: this concern comes only from lab (test-tube) research, not real-world studies in people, so the actual risk is uncertain and probably small. The amount of I3C you get from eating broccoli or cabbage is unlikely to matter. Concentrated supplements are the bigger question mark. If you take both regularly, just run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Paliwal P, Chauhan G, Gautam D, Dash D, Patne SCU, Krishnamurthy S. Indole-3-carbinol improves neurobehavioral symptoms in a cerebral ischemic stroke model. Naunyn Schmiedebergs Arch Pharmacol. 2018;391(6):613-625. 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

Indole-3-carbinol Also Interacts With Other Medications

Indole-3-carbinol has 293 moderate known drug interactions in our database — the Diclofenac one above is one of them. If you take anything else, check it against the full list below.

Moderate 293 No known interaction 2,537 (incl. Diclofenac)
Taking anything else?

Check Another of Your Medications Against Indole-3-carbinol

Covers the 2,830 medications we’ve checked against Indole-3-carbinol. Pick one to open its full report.

From our Q&A

Questions About Indole-3-carbinol or Diclofenac

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Indole-3-carbinol or Diclofenac, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Diclofenac

This page covers Indole-3-carbinol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Diclofenac page lists 306 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), Danshen (major) and Piracetam (major).

By severity: 7 major · 265 moderate · 34 minor.

From our pharmacist’s overview on the Diclofenac page

“Diclofenac (Zorvolex) is an NSAID pain reliever that already stresses the stomach lining and kidneys on its own, so treat this list as a real safety issue, not fine print. Two thirds of the 306 supplements on file can thin the blood or slow clotting, and stacked on an NSAID that raises the odds of stomach bleeding.”

Reviewed by 2 · Jul 18, 2026

Open the Diclofenac interaction page

One more smart check

Taking Indole-3-carbinol as Part of a Dietary Supplement Product? Check It for Interactions

We hold 287 real supplement products containing Indole-3-carbinol, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Indole-3-carbinol. Your product may carry other ingredients that interact with Diclofenac too, on top of Indole-3-carbinol — 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 Indole-3-carbinol and Diclofenac 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 Indole-3-carbinol
Top 25%

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

29 days ago today
Medication Diclofenac
Top 25%

#305 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 Indole-3-carbinol

What is Indole-3-carbinol?

  • Estrogen and hormone balance support
  • Breast and cervical health
  • Prostate health
  • Antioxidant and 'detox' support
  • General cancer-prevention interest

Indole-3-carbinol (I3C) is a compound formed when you eat cruciferous vegetables like broccoli and cabbage, and it is sold as a supplement mainly for hormone-related and cell-protective effects. Most human evidence is preliminary or comes from lab and animal studies, so it should not be relied on to prevent or treat any disease. Talk to your pharmacist or doctor before using it, and avoid it in pregnancy and breastfeeding.

Read the full Indole-3-carbinol monograph & all interactions
Medication

About Diclofenac

What Is Diclofenac Used For?

Brand name: Zorvolex

Diclofenac sodium topical gel is used to treat actinic keratoses (AK) — rough, scaly skin patches that form after years of sun exposure. These patches are considered precancerous, meaning they can develop into skin cancer if left untreated.

This is a topical gel, meaning it is applied directly to the skin over the affected area rather than taken by mouth. It belongs to the NSAID (nonsteroidal anti-inflammatory drug) family.

See full Diclofenac drug information
Keep checking

Other Drugs & Indole-3-carbinol

Browse every other medication we’ve checked against Indole-3-carbinol — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
293Moderate
0Minor
2,536No known interaction
293 Moderate 2,536 No interaction
Moderate

293 interactions

Showing 60 of 293 moderate interactions — see all 293 on the Indole-3-carbinol page.

No interaction 2,536 drugs checked — show the list

We also checked Indole-3-carbinol against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,536 medications checked with no known interaction — see the full Indole-3-carbinol list.

See the full Indole-3-carbinol interactions page
See every supplement checked against Diclofenac, 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
Indole-3-carbinol monograph › Uses, safety, and every drug interaction in one place Diclofenac supplement interactions › Every supplement checked against Diclofenac, ranked by severity Diclofenac 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 Indole-3-carbinol and Diclofenac Together: Common Questions

Can you take Indole-3-carbinol with Diclofenac?
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 Indole-3-carbinol and Diclofenac 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 Diclofenac and Indole-3-carbinol?

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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.