Drug & supplement interaction

Fennel + Amiodarone

Amiodarone brand names: Pacerone, Cordarone.

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

Fennel has a moderate interaction with Amiodarone. Theoretically, fennel might increase levels of drugs metabolized by CYP3A4.

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

Fennel and Amiodarone

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Amiodarone

Amiodarone falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Fennel interacts with.

Theoretically, fennel might increase levels of drugs metabolized by CYP3A4.

In vitro research suggests that fennel inhibits CYP3A4 enzyme activity. This effect has not been reported in humans.
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 uses an enzyme called CYP3A4 to help break down amiodarone. In lab dish studies, fennel appears to slow that enzyme down a bit. If that happened in real life, less amiodarone would get cleared and more could build up in your blood, which could mean stronger effects and a higher chance of side effects like a slow heartbeat, dizziness, or new rhythm problems.

The important caveat: this is only theoretical, based on test-tube research, and it has not been seen in people. Amiodarone is a powerful, narrow-margin heart medicine, so even small shifts are worth respecting. Eating fennel as a food or spice is very unlikely to matter, but before using concentrated fennel supplements or the essential oil, please check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Subehan, Usia, T., Iwata, H., Kadota, S., and Tezuka, Y. Mechanism-based inhibition of CYP3A4 and CYP2D6 by Indonesian medicinal plants. J Ethnopharmacol. 5-24-2006;105(3):449-455. PubMed
  2. Subehan, Zaidi, S. F., Kadota, S., and Tezuka, Y. Inhibition on human liver cytochrome P450 3A4 by constituents of fennel (Foeniculum vulgare): identification and characterization of a mechanism-based inactivator. J Agric.Food Chem. 12-12-2007;55(25):101 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

Fennel Also Interacts With Other Medications

Fennel has 741 moderate known drug interactions in our database — the Amiodarone one above is one of them. If you take anything else, check it against the full list below.

Moderate 741 No known interaction 2,089 (incl. Amiodarone)
Taking anything else?

Check Another of Your Medications Against Fennel

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

From our Q&A

Questions About Fennel or Amiodarone

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

This page covers Fennel only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Amiodarone page lists 210 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 11 major · 163 moderate · 36 minor.

From our pharmacist’s overview on the Amiodarone page

“Amiodarone (Pacerone, Cordarone) treats dangerous heart rhythms, and this is one supplement list I would genuinely be careful with. Of the 210 ingredients on file, 11 carry a major rating, and the everyday one is grapefruit, which blocks the liver enzyme that clears amiodarone and can push the drug's level higher than intended.”

Reviewed by 2 · Jul 18, 2026

Open the Amiodarone interaction page

One more smart check

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

We hold 2,219 real supplement products containing Fennel, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Fennel. Your product may carry other ingredients that interact with Amiodarone too, on top of Fennel — 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 Fennel and Amiodarone 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 Fennel
Top 10%

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

29 days ago today
Medication Amiodarone
Top half

#1,036 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 Fennel

What is Fennel?

Fennel
  • Digestive upset and bloating
  • Infant colic
  • Menstrual cramps
  • Cough and respiratory complaints
  • Breast milk support (traditional)

Fennel is a Mediterranean herb widely used as a food and spice, and traditionally taken for digestive complaints, colic, and menstrual cramps. Some small studies suggest possible benefit for certain stomach and menstrual symptoms, but the evidence is limited. It is generally well tolerated in food amounts, but concentrated supplements and the essential oil should be used with caution and after checking with your pharmacist or doctor.

Read the full Fennel monograph & all interactions
Medication

About Amiodarone

What Is Amiodarone Used For?

Brand names: Pacerone, Cordarone

Amiodarone treats dangerous rhythm problems that start in the lower chambers of the heart: ventricular fibrillation and hemodynamically unstable ventricular tachycardia. In both, the heart beats so abnormally that blood pressure and blood flow can drop.

The tablets (including Pacerone) are for adults with documented, life-threatening, recurrent episodes who have not responded to other antiarrhythmics or cannot tolerate them. The IV injection (including Nexterone) is for starting treatment and preventing frequently recurring episodes in patients who are refractory to other therapy. Injection can also be used when someone needs oral amiodarone but cannot take medicine by mouth.

See full Amiodarone drug information
Keep checking

Other Drugs & Fennel

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

0Major
741Moderate
0Minor
2,088No known interaction
741 Moderate 2,088 No interaction
Moderate

741 interactions

Showing 60 of 741 moderate interactions — see all 741 on the Fennel page.

No interaction 2,088 drugs checked — show the list

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

Showing the 60 most looked-up of 2,088 medications checked with no known interaction — see the full Fennel list.

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

Can you take Fennel with Amiodarone?
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 Fennel and Amiodarone 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 Amiodarone and Fennel?

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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.