Supplements and Flecainide acetate.
Flecainide acetate, sold under the brand names Tambocor, Tambocor XL, is classified under "antiarrhythmic drugs" in the BNF.
Flecainide is a class Ic antiarrhythmic, a sodium channel blocker. UK prescribing includes paroxysmal atrial fibrillation and some other fast heart rhythms, in people whose heart is otherwise structurally normal; it is avoided after a heart attack or with heart failure. The gap between an effective and a harmful level is narrow, and blood levels rise when kidney function falls. It is broken down largely by the liver enzyme CYP2D6, so medicines that block that enzyme can raise it. Dizziness, a racing or irregular heartbeat, or blurred vision on it are worth raising with the prescriber promptly. Because it is taken for a heart rhythm condition, a Distil report leaves out Panax ginseng, Bacopa, Huperzine A and Tongkat Ali for anyone on it, since each may affect heart rate or rhythm.
Below are the 5 documented pairs we have explicitly assessed against Flecainide acetate in the Distil database: 5 caution. The pairs cluster around 2 mechanisms: Haemodynamic interaction (narrow therapeutic window) and Narrow-therapeutic-index prescriber awareness. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Last reviewed 30 October 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Haemodynamic interaction (narrow therapeutic window)
Caution Does Beetroot Extract interact with Flecainide acetate?
Flecainide is a Class Ic antiarrhythmic with a narrow therapeutic window and is sensitive to blood pressure and electrolyte changes. Beetroot lowers blood pressure through the nitric oxide pathway, which can stack with flecainide's haemodynamic profile. At standard supplement doses the combined effect tends to be mild, but the narrow safety margin of flecainide means you should let your cardiologist know if you start beetroot. Do not stack beetroot with hibiscus, garlic, L-citrulline and high-dose magnesium at the same time if you are on flecainide.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Narrow-therapeutic-index prescriber awareness
Caution Does Bacopa Monnieri interact with Flecainide acetate?
Bacopa may slow the heart rate a little: in one 12-week trial, heart rate held steady on bacopa while it rose on placebo. The effect is small, but with flecainide, which is taken for a heart rhythm condition, it is safest not to take bacopa unless your cardiologist agrees.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Huperzine A interact with Flecainide acetate?
Huperzine A works like some dementia medicines that can slow the heart rate and, rarely, cause fainting. Flecainide is taken for a heart rhythm condition and has a narrow safe range, so it is safest not to take huperzine A with it unless your cardiologist agrees.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Panax Ginseng interact with Flecainide acetate?
Flecainide slows electrical conduction through the heart, which shows as a longer QT interval on an ECG, and in a small trial in healthy adults a dose of Panax ginseng lengthened the QT interval slightly too, so the two may add up. With flecainide, which is taken for a heart rhythm condition and has a narrow safe range, it is safest not to take Panax ginseng unless your cardiologist agrees.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Tongkat Ali interact with Flecainide acetate?
One man developed atrial flutter, a fast abnormal heart rhythm, two days after starting tongkat ali, and it settled within a day of stopping. That is a single report, but with flecainide, which is taken for a heart rhythm condition, it is safest not to take tongkat ali unless your cardiologist agrees.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
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How the checker decides
Every result has a source
Each pair we have assessed is cited to a published study (PMID) or the British National Formulary, so you can read the source yourself.
Four kinds of answer
Severe, caution, no known interaction, and not yet assessed. A pair we have not assessed is never shown as clear.
- Severe
- Caution
- No known interaction
- Not yet assessed
Nothing in our data is not a clearance
When nothing in our data records a problem with a pair, the result says no known interaction at typical doses, which is not a clearance: your pharmacist or GP can check the pair against your full medical history.
A full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
£49 until 30 June 2027 · £79 from 1 July 2027.
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