Medication interaction hub

What Supplements Interact with Flecainide?

Flecainide brand name: Tambocor. Every interaction below applies to the brands too.

86 Interactions 7 Major 61 Moderate 18 Minor
Curated & coded by · Clinical Pharmacist · Updated September 26, 2026

Drug–supplement interaction data sourced from Natural Medicines Pro, the licensed clinical database from TRC Healthcare / Therapeutic Research, with additional analysis by the HelloPharmacist Pharmacist Team. Our sources · Editorial policy

What is this page for?

One answer, for one medication: what supplements and herbal products interact with Flecainide? Every vitamin, herb, and supplement ingredient we’ve checked against it is on this page, ranked by severity, each linking to the full report for that exact pair.

This page covers supplement interactions only — to check Flecainide against your other medications, use the drug–drug interaction checker. Educational information from our licensed clinical databases, not medical advice. Our editorial policy

HelloPharmacist Bottom Line
Our Pharmacist Explains
What is this? The interaction data in the HelloPharmacist supplement database is licensed from Natural Medicines Pro by TRC Healthcare (Therapeutic Research). HelloPharmacist pharmacists often add our own analysis and context on top of that licensed data — such as this Bottom Line summary and the notes on individual interaction pages — and any such commentary is noted as ours.

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 to a risk this drug already carries. The seventh, activated charcoal, binds medicines in the gut and can cut how much flecainide reaches the bloodstream.

The largest group, 60 ingredients with goldenseal among them, slows the CYP2D6 enzyme that clears flecainide, which can push its blood level higher. Flecainide leaves little margin between a level that works and one that causes harm, so those milder entries still count. A smaller cluster of charcoals and thick fibers can blunt absorption of oral drugs; space them well away from when you take flecainide. The remaining 61 moderates and 18 minors deserve a look, but none carries the urgency of those seven.

— , Clinical Pharmacist · July 18, 2026

Major 7 Moderate 61 Minor 18 No known interaction 1,366

This box checks one ingredient at a time (like turmeric or magnesium). Taking a supplement product with a whole label of ingredients? Search the product instead — we check every ingredient on it ↓

Top Ingredient Interactions

Flecainide: Top Interactions at a Glance

The most significant Flecainide supplement & herbal interactions, colored by severity. Tap any ingredient to open the full report for that pair.

Showing the 12 highest-ranked of 86 interacting ingredients — plus 1,366 more checked with no known interaction. See the complete ranked list.

Start here

The Major Interactions to Know About

The most clinically significant Flecainide + supplement combinations in our database, best-documented first. Open any card for the full report.

Major Likelihood Probable Activated Charcoal + Flecainidei

Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.

Read the full interaction Major Likelihood Probable Arsenic + Flecainidei

Arsenic trioxide can prolong the QT interval.

Read the full interaction Major Likelihood Probable Cesium + Flecainidei

Theoretically, taking cesium concomitantly with other drugs that prolong the QT interval may increase the risk of ventricular arrhythmias and death.

Read the full interaction Major Likelihood Probable Ephedra + Flecainidei

Theoretically, ephedra might have an additive effect with drugs that prolong the QT interval.

Read the full interaction Major Likelihood Probable Grapefruit + Flecainidei

Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT interval-prolonging drug...

Read the full interaction Major Likelihood Probable Sida Cordifolia + Flecainidei

Theoretically, Sida cordifolia might increase the risk of additive QT interval prolongation when taken with QT interval-prolonging drugs.

Read the full interaction
The complete list

Every Supplement Checked Against Flecainide

All 1,452 ingredients in our database, ranked by severity — 86 with a Flecainide interaction on file and 1,366 with none found. Filter by severity or search any ingredient; hover the for what each ingredient is.

Looking for an interaction with a specific supplement product? Search products instead ↓

Straight answers

Can You Take It With Flecainide?

One-line answers, one card per combination — scroll through today’s 20 and tap any card for the full report. A different set rotates in daily until every combination has had its turn.

Can you take Quercetin with Flecainide?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, concomitant use might increase the levels and adverse effects of CYP2D6 substrates.

Full Quercetin + Flecainide answer

Can you take Grapefruit with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Grapefruit or grapefruit juice, especially if consumed in large amounts, can cause additive QT interval prolongation when taken with QT inte...

Full Grapefruit + Flecainide answer

Can you take Black Psyllium with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, psyllium might increase, decrease, or have no effect on the absorption of oral drugs.

Full Black Psyllium + Flecainide answer

Can you take Hordenine with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Hordenine weakly inhibits cytochrome P450 2D6 (CYP2D6) enzymes in vitro.

Full Hordenine + Flecainide answer

Can you take Karaya Gum with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Co-administration of oral drugs with bulk forming laxatives such as karaya gum may decrease, increase, or have no effect on the absorption o...

Full Karaya Gum + Flecainide answer

Can you take Marshmallow with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, mucilage in marshmallow might impair absorption of oral drugs.

Full Marshmallow + Flecainide answer

Can you take Melatonin with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, melatonin might increase levels of drugs metabolized by CYP2D6.

Full Melatonin + Flecainide answer

Can you take Xanthan Gum with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, xanthan gum can alter the absorption of oral drugs due to its fiber qualities.

Full Xanthan Gum + Flecainide answer

Can you take Eleuthero with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Theoretically, eleuthero might increase levels of drugs metabolized by CYP2D6.

Full Eleuthero + Flecainide answer

Can you take Humann Superbeets Heart Chews with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Each serving of HumanN SuperBeets includes 150mg of grape seed extract (2 chews).

Full Humann Superbeets Heart Chews + Flecainide answer

Can you take Kava with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. It is unclear if kava inhibits CYP1A2; research is conflicting.

Full Kava + Flecainide answer

Can you take Valerian with Flecainide?

Minor Usually — this is a minor-rated interaction, generally not clinically significant but worth mentioning to your pharmacist. Valerian does not seem to have a clinically relevant effect on levels of drugs metabolized by CYP2D6.

Full Valerian + Flecainide answer

Can you take Activated Charcoal with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the rout...

Full Activated Charcoal + Flecainide answer

Can you take Arsenic with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Arsenic trioxide can prolong the QT interval.

Full Arsenic + Flecainide answer

Can you take Cesium with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Theoretically, taking cesium concomitantly with other drugs that prolong the QT interval may increase the risk of ventricular arrhythmias an...

Full Cesium + Flecainide answer

Can you take Ephedra with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Theoretically, ephedra might have an additive effect with drugs that prolong the QT interval.

Full Ephedra + Flecainide answer

Can you take Sida Cordifolia with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Theoretically, Sida cordifolia might increase the risk of additive QT interval prolongation when taken with QT interval-prolonging drugs.

Full Sida Cordifolia + Flecainide answer

Can you take American Hellebore with Flecainide?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. American hellebore, also known as Veratrum viride, contains alkaloids that can potentially prolong the QT interval on an electrocardiogram (...

Full American Hellebore + Flecainide answer

Can you take Ayahuasca with Flecainide?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, ayahuasca might increase plasma concentrations of CYP2D6 substrates.

Full Ayahuasca + Flecainide answer

Can you take Coffee Charcoal with Flecainide?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Coffee charcoal can reduce the absorption of orally administered drugs and should be separated from oral drug administration by at least two...

Full Coffee Charcoal + Flecainide answer
Read the list like a pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each entry links to a full report with the clinical detail, likelihood, evidence level, and citations for that exact combination.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

How Does Our Interaction Checker Work?

Behind every verdict on this page is a category system. Our source database doesn’t document supplement interactions drug-by-drug — it documents them against groups of medications that behave the same way (for example, “drugs processed by the CYP3A4 liver enzyme” or “blood-thinning medications”).

So the check works in three steps: (1) Flecainide is classified into the pharmacology categories it belongs to, (2) every supplement interaction documented against any of those categories is inherited by Flecainide, and (3) each ingredient keeps its own severity, likelihood, and evidence grades from the underlying record. That’s why one supplement can carry several records for one drug — it may interact through more than one category.

Flecainide sits in 4 interaction categories. Open any one to see what the group means:

Cytochrome P450 2D6 (Cyp2D6) Substrates 60 ingredients

A drug-metabolism group: these medications are processed by the named liver enzyme (a cytochrome P450). Supplements that speed this enzyme up or slow it down can lower or raise the medication's levels in your body.

60 of the supplement ingredients on this page reach Flecainide through this category.

Oral Drugs 17 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

17 of the supplement ingredients on this page reach Flecainide through this category.

Qt Interval-Prolonging Drugs 13 ingredients

Medications that can affect the heart's electrical rhythm (the QT interval). Supplements with similar effects can add to that risk.

13 of the supplement ingredients on this page reach Flecainide through this category.

Flecainide (Tambocor) 1 ingredient

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

1 of the supplement ingredient on this page reaches Flecainide through this category.

About Flecainide

Flecainide is an antiarrhythmic medication used to prevent certain life-threatening irregular heartbeats.

Generic name: Flecainide  ·  Brand name: Tambocor.

See the full Flecainide drug information
Check a real product

Take a Supplement Product? Check the Whole Bottle Against Flecainide

Most supplements are combination products — and the interaction may come from an ingredient you didn’t buy it for. Search any product below (or scan its label) and we’ll check every ingredient on it against Flecainide.

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Pharmacist Counseling Corner

Flecainide & Supplements: Common Questions

What supplements interact with Flecainide?
More than you might expect — 86 in total, though they are far from equal: 7 are rated major, 61 moderate, and 18 minor. The ranked list on this page puts the ones that genuinely matter first, and every entry opens a full report on that exact pair. The highest-ranked right now: Activated Charcoal, Arsenic, Cesium.
Which Flecainide supplement interactions are the most serious?
The 7 major-rated combinations — led by Activated Charcoal, Arsenic, Cesium, Ephedra and Grapefruit — deserve real caution: these are the ones generally best avoided, or used only with your prescriber watching. If you take any of them today, don't panic and don't stop anything abruptly — call your pharmacist first. Jump to the ranked list.
Can I take vitamins or supplements while on Flecainide?
Usually yes — most people on Flecainide can take most supplements. The catch is the exceptions, and they aren't always the exotic ones (St. John's Wort trips up more prescriptions than almost anything sold next to it). Look up each ingredient you actually take in the list above, and treat "no known interaction" as a green-ish light, not a guarantee. Try the label scanner or the interaction checker.
Do brands like Tambocor have the same supplement interactions as Flecainide?
Yes — Tambocor all contain Flecainide, so everything on this page applies to them equally. Interactions belong to the active drug, never to the brand on the box; the same is true of generics.
Where do these interaction ratings come from?
Every rating comes from the Natural Medicines database — the same evidence-graded reference pharmacists and hospitals use — and each interaction carries three separate grades: severity (how bad it can be), likelihood (how well it's documented in studies and case reports), and an evidence level. Our pharmacists review the content; we never let an AI decide an interaction. See how to read the ratings and our editorial policy.
What about Flecainide and my other medications?
This page covers Flecainide against supplements and herbal ingredients. Checking Flecainide against your other prescription or OTC medications is a different tool — our drug interaction checker covers that side. Head to the drug–drug interaction checker, or read the full Flecainide drug information.

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

Where next

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Sourcing

Where This Data Comes From — and Why You Can Trust It

🧪 Licensed clinical database

Every interaction verdict on this page comes from Natural Medicines Pro (TRC Healthcare / Therapeutic Research) — the same evidence-graded reference used by pharmacists and hospitals. We license this data directly; we do not scrape it, and no AI invents an interaction.

🧑‍⚕️ Pharmacist review

This page is curated and coded by , Clinical Pharmacist, with additional analysis by the HelloPharmacist Pharmacist Team. Editorial commentary is ours; the licensed interaction records are shown as sourced.

🔄 Kept current

Our interaction database refreshes on a weekly cycle, and this page re-checks the live database every time it’s rebuilt — what you see reflects the database as of September 26, 2026.

🔍 Full transparency

How every dataset on this site is sourced, licensed, and updated is documented publicly: our data sources · editorial policy · how we use AI.

Educational information, not medical advice. An interaction being on file does not mean it will happen to you — and absence of one is not proof of safety. Never start or stop a medication or supplement without talking to your pharmacist or doctor.