Drug & supplement interaction

Greater Celandine + Flecainide

Flecainide brand name: Tambocor.

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

Greater Celandine has a moderate interaction with Flecainide. Research in vitro shows that chelidonine, a constituent of greater celandine, inhibits cytochrome P450 2D6 (CYP2D6) enzyme activity.

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

Greater Celandine and Flecainide

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

Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

Why this applies to Flecainide

Flecainide falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Greater Celandine interacts with.

Research in vitro shows that chelidonine, a constituent of greater celandine, inhibits cytochrome P450 2D6 (CYP2D6) enzyme activity. Theoretically, greater celandine might increase levels of drugs metabolized by CYP2D6.
Some drugs metabolized by CYP2D6 include amitriptyline (Elavil), clozapine (Clozaril), codeine, desipramine (Norpramin), donepezil (Aricept), fentanyl (Duragesic), flecainide (Tambocor), fluoxetine (Prozac), meperidine (Demerol), methadone (Dolophine), metoprolol (Lopressor, Toprol XL), olanzapine (Zyprexa), ondansetron (Zofran), tramadol (Ultram), trazodone (Desyrel), and many 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 heart rhythm medicine. Your body clears flecainide partly through a liver enzyme called CYP2D6. In lab studies, one compound in greater celandine (chelidonine) appears to slow that enzyme down. If that holds true in people, your flecainide could clear more slowly and build up to higher levels than expected.

That matters because flecainide is a narrow-window drug, meaning small changes can tip it from helpful into harmful. Higher levels could mean dizziness, blurred vision, trouble breathing, or even new or worsening irregular heartbeats. Right now this is only theoretical, based on lab work, not human studies. Still, greater celandine also carries a real risk of liver damage, so please check with your doctor or pharmacist before combining the two.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu Y, Cui T, Peng Y, Ji M, Zheng J. Mechanism-based inactivation of cytochrome P450 2D6 by chelidonine. J Biochem Mol Toxicol. 2019;33(2):e22251. 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

Greater Celandine Also Interacts With Other Medications

Greater Celandine has 624 moderate known drug interactions in our database — the Flecainide one above is one of them. If you take anything else, check it against the full list below.

Moderate 624 No known interaction 2,206 (incl. Flecainide)
Taking anything else?

Check Another of Your Medications Against Greater Celandine

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

From our Q&A

Questions About Greater Celandine or Flecainide

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

This page covers Greater Celandine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Flecainide page lists 86 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), Cesium (major) and Ephedra (major).

By severity: 7 major · 61 moderate · 18 minor.

From our pharmacist’s overview on the Flecainide page

“Flecainide (Tambocor) exists to control serious heart rhythm problems, so anything that disturbs the rhythm it protects deserves genuine caution. Six of the seven major-rated entries among the 86 supplements and herbs on file, grapefruit in large amounts included, can prolong the QT interval, the heart's electrical reset time, adding t…”

Reviewed by 2 · Jul 18, 2026

Open the Flecainide interaction page

One more smart check

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

We hold 11 real supplement products containing Greater Celandine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Greater Celandine. Your product may carry other ingredients that interact with Flecainide too, on top of Greater Celandine — 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 Greater Celandine and Flecainide 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 Greater Celandine
Steady interest

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

29 days ago today
Medication Flecainide
Top half

#722 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 Greater Celandine

What is Greater Celandine?

Greater Celandine
  • Digestive and gallbladder complaints
  • Stomach cramps and bloating
  • Topical use for warts and skin growths
  • Liver and gallbladder 'cleansing'
  • Mild pain relief

Greater celandine is a traditional herb most often promoted for digestive and gallbladder complaints, but solid human evidence for any use is lacking. More importantly, it has been linked to serious and sometimes severe liver injury, so most experts advise against taking it by mouth. If you are considering it, talk with your pharmacist or doctor first.

Read the full Greater Celandine monograph & all interactions
Medication

About Flecainide

What Is Flecainide Used For?

Brand name: Tambocor

Flecainide Acetate tablets are used to prevent episodes of certain abnormal heart rhythms. In patients without structural heart disease, it is approved to prevent paroxysmal supraventricular tachycardia (PSVT — episodes of rapid heart rate starting above the ventricles) and paroxysmal atrial fibrillation/flutter (PAF — intermittent episodes of irregular, rapid heart rhythm in the upper chambers), when these cause disabling symptoms.

Flecainide Acetate tablets are also used to prevent life-threatening ventricular arrhythmias — dangerous rapid rhythms starting in the lower chambers of the heart, such as sustained ventricular tachycardia. It is not recommended for less serious ventricular arrhythmias, for patients with a recent heart attack, or for chronic (ongoing, persistent) atrial fibrillation.

See full Flecainide drug information
Keep checking

Other Drugs & Greater Celandine

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

0Major
624Moderate
0Minor
2,205No known interaction
624 Moderate 2,205 No interaction
Moderate

624 interactions

Showing 60 of 624 moderate interactions — see all 624 on the Greater Celandine page.

No interaction 2,205 drugs checked — show the list

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

Showing the 60 most looked-up of 2,205 medications checked with no known interaction — see the full Greater Celandine list.

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

Can you take Greater Celandine with Flecainide?
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 Greater Celandine and Flecainide 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 Flecainide and Greater Celandine?

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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.