Drug & supplement interaction

Passion Flower + Warfarin Sodium

Warfarin Sodium brand names: Coumadin, Panwarfin, Sofarin.

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

Passion Flower has a minor interaction with Warfarin Sodium. Theoretically, passion flower might decrease the effects of CYP3A4 substrates.

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

Passion Flower and Warfarin Sodium

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

Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Warfarin Sodium

Warfarin Sodium falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Passion Flower interacts with.

Theoretically, passion flower might decrease the effects of CYP3A4 substrates.
In vitro research suggests that passion flower can induce CYP3A4 enzymes, albeit to a much lower degree than rifampin, a known CYP3A4 inducer.
Severity Minor 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 warfarin and passion flower. Warfarin is partly cleared by a liver enzyme called CYP3A4. Lab studies (test tube only) hint that passion flower might gently speed up that enzyme, which could in theory clear warfarin a little faster and slightly weaken its blood-thinning effect. In real life that might mean a touch less protection against clots.

That said, this is very weak evidence, the effect was much smaller than known strong inducers, and warfarin is dosed using your INR blood test. Because warfarin is so finely tuned, even small shifts can matter, so I wouldn't just add or stop passion flower on your own. Mention it to your pharmacist or doctor so they can keep an eye on your INR.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Mazzari ALDA, Lacerda MG, Milton FA, et al. In vitro effects of European and Latin-American medicinal plants in CYP3A4 gene expression, glutathione levels, and P-glycoprotein activity. Front Pharmacol 2022;13:826395. 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

Passion Flower Also Interacts With Other Medications

Passion Flower has 248 moderate, 587 minor known drug interactions in our database — the Warfarin Sodium one above is one of them. If you take anything else, check it against the full list below.

Moderate 248 Minor 587 No known interaction 1,995 (incl. Warfarin Sodium)
Taking anything else?

Check Another of Your Medications Against Passion Flower

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

From our Q&A

Questions About Passion Flower or Warfarin Sodium

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Passion Flower or Warfarin Sodium, 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 Warfarin Sodium

This page covers Passion Flower only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Warfarin Sodium page lists 361 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alfalfa (major), American Ginseng (major), Beer (major) and Cannabis (major).

Open the Warfarin Sodium interaction page

One more smart check

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

We hold 2,129 real supplement products containing Passion Flower, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Passion Flower. Your product may carry other ingredients that interact with Warfarin Sodium too, on top of Passion Flower — 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 Passion Flower and Warfarin Sodium 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 Passion Flower
Top 10%

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

29 days ago today
Medication Warfarin Sodium
Top 1%

#18 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 Passion Flower

What is Passion Flower?

Passion Flower
  • Anxiety and stress
  • Trouble sleeping
  • Restlessness
  • Mild nervous tension
  • Muscle tension

Passion flower is a traditional calming herb that many people use for anxiety and sleep. Early studies hint it may help with mild anxiety and restlessness, but the evidence is limited and more research is needed. It is generally well tolerated short-term, but should be avoided in pregnancy and discussed with your pharmacist or doctor first.

Read the full Passion Flower monograph & all interactions
Medication

About Warfarin

What Is Warfarin Used For?

Brand names: Coumadin, Panwarfin, Sofarin

Warfarin sodium tablets and Jantoven tablets are both used to prevent and treat venous thrombosis (blood clots in the veins) and pulmonary embolism (a clot in the lungs). They are also used to prevent clot-related complications in people with atrial fibrillation (an irregular heart rhythm) or who have had a heart valve replaced.

In people who have had a heart attack, warfarin is used to reduce the risk of death, another heart attack, stroke, or other clotting events. It does not dissolve an existing clot, but it helps prevent the clot from growing and stops new dangerous clots from forming.

See full Warfarin drug information
Keep checking

Other Drugs & Passion Flower

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

0Major
248Moderate
587Minor
1,994No known interaction
248 Moderate 587 Minor 1,994 No interaction
Moderate

248 interactions

Showing 60 of 248 moderate interactions — see all 248 on the Passion Flower page.

Minor

587 interactions

Showing 60 of 587 minor interactions — see all 587 on the Passion Flower page.

No interaction 1,994 drugs checked — show the list

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

Showing the 60 most looked-up of 1,994 medications checked with no known interaction — see the full Passion Flower list.

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

Can you take Passion Flower with Warfarin Sodium?
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 Passion Flower and Warfarin Sodium 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 Warfarin Sodium and Passion Flower?

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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.