Drug & supplement interaction

Ipriflavone + Flutamide

Flutamide brand names: Eulexin, Euflex.

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

Ipriflavone has a moderate interaction with Flutamide. Ipriflavone is thought to competitively inhibit cytochrome P450 1A2 (CYP1A2).

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

Ipriflavone and Flutamide

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

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Why this applies to Flutamide

Flutamide falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Ipriflavone interacts with.

Ipriflavone is thought to competitively inhibit cytochrome P450 1A2 (CYP1A2). Theoretically, concurrent use of ipriflavone and drugs metabolized by these enzymes might result in decreased drug elimination, increased serum levels, and potential toxicity. Some drugs metabolized by CYP1A2 include clozapine (Clozaril), cyclobenzaprine (Flexeril), fluvoxamine (Luvox), haloperidol (Haldol), imipramine (Tofranil), mexiletine (Mexitil), olanzapine (Zyprexa), Pentazocine (Talwin), propranolol (Inderal), tacrine (Cognex), theophylline (Slo-bid, Theo-Dur, others), zileuton (Zyflo), Zolmitriptan (Zomig), and others.
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 for your prostate cancer medicine. Flutamide is processed in the liver, and CYP1A2 is one of the enzymes that helps clear it. Ipriflavone may gently block that enzyme. In theory, that could slow how fast Flutamide leaves your body and nudge its levels up a bit, which might mean more of its usual effects, like hot flashes, breast tenderness, diarrhea, or stress on the liver.

I want to be honest, though: this is based only on lab data, not real patients, so it's a possible concern, not a proven one. Flutamide already needs liver monitoring, so I wouldn't add ipriflavone without checking first. Please run it by your oncology team or pharmacist before combining the two.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Monostory K, Vereczkey L, Levai F, et al. Ipriflavone as an inhibitor of human cytochrome P450 enzymes. Br J Pharmacol 1998;123:605-10. 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

Ipriflavone Also Interacts With Other Medications

Ipriflavone has 390 moderate known drug interactions in our database — the Flutamide one above is one of them. If you take anything else, check it against the full list below.

Moderate 390 No known interaction 2,440 (incl. Flutamide)
Taking anything else?

Check Another of Your Medications Against Ipriflavone

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

Everything else you take

See Every Supplement That Interacts With Flutamide

This page covers Ipriflavone only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Flutamide page lists 189 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 143 moderate · 43 minor.

From our pharmacist’s overview on the Flutamide page

“A man taking flutamide (Eulexin) to block testosterone during prostate cancer treatment cannot afford big swings in the drug's level, and most of the 189 supplements on this page are capable of causing exactly that. The bulk of them work through the liver enzyme CYP3A4, which breaks flutamide down.”

Reviewed by 2 · Jul 18, 2026

Open the Flutamide interaction page

One more smart check

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

We hold 204 real supplement products containing Ipriflavone, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ipriflavone. Your product may carry other ingredients that interact with Flutamide too, on top of Ipriflavone — 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 Ipriflavone and Flutamide 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 Ipriflavone
Top half

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

29 days ago today
Medication Flutamide
Top 10%

#194 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 Ipriflavone

What is Ipriflavone?

Ipriflavone
  • Bone density and osteoporosis
  • Postmenopausal bone loss
  • Athletic performance
  • Tinnitus related to bone disorders

Ipriflavone is a synthetic isoflavone studied mainly for bone health and osteoporosis, but high-quality research has not shown that it reliably prevents fractures or builds strong bone. Because it can lower white blood cell counts in some people and its long-term safety is not well established, talk with your pharmacist or doctor before using it.

Read the full Ipriflavone monograph & all interactions
Medication

About Flutamide

What Is Flutamide Used For?

Brand names: Eulexin, Euflex

Eulexin (flutamide) capsules are used to treat prostate cancer in men. They are always used together with an LHRH agonist (a hormone-lowering injection), never alone.

Eulexin is indicated for two stages of prostate cancer: locally confined Stage B2-C prostate cancer (used alongside goserelin acetate and radiation therapy, starting eight weeks before radiation begins) and Stage D2 metastatic prostate cancer (cancer that has spread beyond the prostate, taken with an LHRH agonist until the disease progresses).

See full Flutamide drug information
Keep checking

Other Drugs & Ipriflavone

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

0Major
390Moderate
0Minor
2,439No known interaction
390 Moderate 2,439 No interaction
Moderate

390 interactions

Showing 60 of 390 moderate interactions — see all 390 on the Ipriflavone page.

No interaction 2,439 drugs checked — show the list

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

Showing the 60 most looked-up of 2,439 medications checked with no known interaction — see the full Ipriflavone list.

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

Can you take Ipriflavone with Flutamide?
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 Ipriflavone and Flutamide 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 Flutamide and Ipriflavone?

Our pharmacists answer your medication & supplement questions — free.

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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.