Drug & supplement interaction

Red Clover + Pirfenidone

Pirfenidone brand name: Esbriet.

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

Red Clover has a minor interaction with Pirfenidone. Theoretically, red clover might increase levels of drugs metabolized by CYP1A2; however, a small clinical study found no effect.

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

Red Clover and Pirfenidone

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

Minor

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Why this applies to Pirfenidone

Pirfenidone falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Red Clover interacts with.

Theoretically, red clover might increase levels of drugs metabolized by CYP1A2; however, a small clinical study found no effect.
In vitro evidence shows that red clover inhibits CYP1A2. However, a clinical study in healthy postmenopausal individuals shows that taking red clover capsules standardized to contain 60 mg isoflavones twice daily for 14 days does not affect the pharmacokinetics of caffeine, a CYP1A2 probe substrate.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the gist for Esbriet (pirfenidone): your liver clears it largely through an enzyme called CYP1A2. In a test tube, red clover's isoflavones look like they might slow that enzyme down, which in theory could let pirfenidone build up a bit and make side effects (nausea, stomach upset, tiredness, dizziness, or sun sensitivity) more likely. Pirfenidone is the active drug itself, not a prodrug, so more in your system means stronger effects, not weaker.

The reassuring part: this is only lab data, and a real human study found red clover did not change how a CYP1A2 marker was processed. So a real-world problem is unlikely. Still, it's worth a quick chat with your pharmacist or doctor before adding red clover.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Unger M, Frank A. Simultaneous determination of the inhibitory potency of herbal extracts on the activity of six major cytochrome P450 enzymes using liquid chromatography/mass spectrometry and automated online extraction. Rapid Commun Mass Spectrom 2004;1 PubMed
  2. Chen L, Choi J, Leonard SW, et al. No Clinically Relevant Pharmacokinetic Interactions of a Red Clover Dietary Supplement with Cytochrome P450 Enzymes in Women. J Agric Food Chem. 2020;68(47):13929-13939. 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

Red Clover Also Interacts With Other Medications

Red Clover has 44 moderate, 822 minor known drug interactions in our database — the Pirfenidone one above is one of them. If you take anything else, check it against the full list below.

Moderate 44 Minor 822 No known interaction 1,964 (incl. Pirfenidone)
Taking anything else?

Check Another of Your Medications Against Red Clover

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

Everything else you take

See Every Supplement That Interacts With Pirfenidone

This page covers Red Clover only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Pirfenidone page lists 115 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Adrafinil (moderate), African Wild Potato (moderate), Alfalfa (moderate) and Angelica Archangelica (moderate).

By severity: 1 major · 80 moderate · 34 minor.

From our pharmacist’s overview on the Pirfenidone page

“Pirfenidone (Esbriet) slows the lung scarring of idiopathic pulmonary fibrosis, and when a drug is doing that kind of work, this is not a list to skim. Most of the 115 ingredients on file touch CYP1A2, the liver enzyme that clears pirfenidone, so they can push its blood level up (more nausea and liver strain) or drag it down and quietl…”

Reviewed by 2 · Jul 18, 2026

Open the Pirfenidone interaction page

One more smart check

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

We hold 1,480 real supplement products containing Red Clover, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Red Clover. Your product may carry other ingredients that interact with Pirfenidone too, on top of Red Clover — 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 Red Clover and Pirfenidone 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 Red Clover
Top 25%

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

29 days ago today
Medication Pirfenidone
Top 25%

#692 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 Red Clover

What is Red Clover?

Red Clover
  • Menopause symptoms (hot flashes)
  • High cholesterol
  • Bone health/osteoporosis
  • Skin and hair concerns
  • Women's health

Red clover is a plant rich in isoflavones (plant compounds with weak estrogen-like activity) that is most often used for menopause symptoms like hot flashes. The evidence is mixed and generally weak, with some studies showing modest benefit and others showing none. Because of its hormone-like effects, it's not for everyone—talk with your pharmacist or doctor before trying it, especially if you have a hormone-sensitive condition.

Read the full Red Clover monograph & all interactions
Medication

About Pirfenidone

What Is Pirfenidone Used For?

Brand name: Esbriet

Pirfenidone — available as capsules and tablets under the brand name Esbriet, as well as generic pirfenidone products — is indicated for the treatment of idiopathic pulmonary fibrosis (IPF), a chronic, progressive disease in which scar tissue builds up in the lungs and makes breathing increasingly difficult.

Esbriet capsules and tablets, pirfenidone capsules, and pirfenidone tablets are each specifically approved for IPF. No other uses are supported by the available product labels.

See full Pirfenidone drug information
Keep checking

Other Drugs & Red Clover

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

0Major
44Moderate
822Minor
1,963No known interaction
44 Moderate 822 Minor 1,963 No interaction
Moderate

44 interactions

Minor

822 interactions

Showing 60 of 822 minor interactions — see all 822 on the Red Clover page.

No interaction 1,963 drugs checked — show the list

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

Showing the 60 most looked-up of 1,963 medications checked with no known interaction — see the full Red Clover list.

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

Can you take Red Clover with Pirfenidone?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Red Clover and Pirfenidone interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Pirfenidone and Red Clover?

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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.