Supplements and Digoxin.
Digoxin, sold under the brand name Lanoxin, is a cardiac glycoside: it increases cardiac contractility and slows AV conduction. The therapeutic window is narrow.
Digoxin is a cardiac glycoside. In current UK clinical practice that means digoxin. The therapeutic window is narrow. Trough levels are monitored because the gap between therapeutic and toxic concentrations is small. Digoxin clearance is renal, and any decline in renal function (acute kidney injury, dehydration, CKD progression) pushes plasma levels up. The supplement surface includes anything that affects renal handling, anything that depletes potassium (since hypokalaemia worsens digoxin toxicity), and anything that inhibits P-glycoprotein. St John's Wort induces P-gp and lowers digoxin levels. Certain supplements at high doses inhibit P-gp and raise them. Real liquorice at high intake is the textbook concerning combination, because it both depletes potassium and acts on cardiac conduction itself. Deglycyrrhizinated (DGL) liquorice has the responsible compound removed and does not deplete potassium. Digoxin toxicity presents with nausea, visual changes (a yellow or green tinge), and arrhythmia. Because it is often 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 15 documented pairs we have explicitly assessed against Digoxin in the Distil database: 15 caution. The pairs cluster around 10 mechanisms: Absorption interference, Additive bradycardia (slowed heart rate), Blood-test (assay) interference, Mineral chelation (absorption), Digoxin assay interference, Digoxin-potassium balance (keep in range), Hypercalcaemia risk, Narrow-therapeutic-index prescriber awareness, P-glycoprotein induction (lowers drug levels), and P-glycoprotein inhibition (raises drug levels). 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.
Absorption interference
Caution Does Psyllium Husk interact with Digoxin?
Psyllium taken at the same moment as digoxin may slightly reduce how much digoxin you absorb, though a controlled study found no effect on steady digoxin levels over time. As a precaution with a narrow-margin drug, take psyllium a couple of hours apart from your digoxin.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive bradycardia (slowed heart rate)
Caution Does Huperzine A interact with Digoxin?
Huperzine A works like some dementia medicines that can slow the heart rate, and digoxin slows it too, so together they may make your pulse too slow and cause dizziness or fainting. With digoxin, which is usually taken for atrial fibrillation or heart failure, it is safest not to take huperzine A 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.
Blood-test (assay) interference
Caution Does Panax Ginseng interact with Digoxin?
Asian (Panax) ginseng can throw off the blood test that measures your digoxin level, making the reading look higher or lower than it really is rather than changing the actual amount of digoxin in your body. Because digoxin has a narrow safe range and doses are adjusted from that blood test, a misleading result matters. If you take Panax ginseng, tell whoever checks your digoxin level so the result can be read correctly, and do not adjust your digoxin dose yourself.
Evidence: Supported by human study data.
Mineral chelation (absorption)
Caution Does Magnesium interact with Digoxin?
There are two things to know here, and on balance magnesium is more helpful than harmful. Taking magnesium at the same time as digoxin can slightly reduce how much digoxin you absorb, so it is sensible to separate them by about two hours. At the same time, a low magnesium level makes digoxin more likely to cause dangerous heart rhythms, so keeping your magnesium in the normal range is protective. Because digoxin has a narrow safe range, tell whoever prescribes it that you take magnesium.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Magnesium Glycinate interact with Digoxin?
There are two things to know here, and on balance magnesium is more helpful than harmful. Taking magnesium at the same time as digoxin can slightly reduce how much digoxin you absorb, so it is sensible to separate them by about two hours. At the same time, a low magnesium level makes digoxin more likely to cause dangerous heart rhythms, so keeping your magnesium in the normal range is protective. Because digoxin has a narrow safe range, tell whoever prescribes it that you take magnesium.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Magnesium L-Threonate interact with Digoxin?
There are two things to know here, and on balance magnesium is more helpful than harmful. Taking magnesium at the same time as digoxin can slightly reduce how much digoxin you absorb, so it is sensible to separate them by about two hours. At the same time, a low magnesium level makes digoxin more likely to cause dangerous heart rhythms, so keeping your magnesium in the normal range is protective. Magnesium L-threonate is still elemental magnesium, so both points apply. Because digoxin has a narrow safe range, tell whoever prescribes it that you take magnesium.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Digoxin assay interference
Caution Does Eleuthero interact with Digoxin?
Siberian ginseng can make a digoxin blood test read higher (or lower) than your true level, depending on which test the lab uses. There is one older case where digoxin readings rose while taking it and fell each time it was stopped. Because digoxin has a narrow safe range, tell your GP or cardiology team if you take Siberian ginseng, and mention it before any digoxin level is checked.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Digoxin-potassium balance (keep in range)
Caution Does Potassium interact with Digoxin?
Potassium needs careful balance on digoxin, so do not start a potassium supplement on your own while taking it. Keeping your potassium in the normal range actually matters: when potassium runs low, digoxin becomes more toxic and can affect the heart rhythm, so a supplement is not something to simply avoid; but too much potassium can reduce how well digoxin works and, if it climbs too high, add to the risk of a slow or irregular heartbeat. Let your doctor decide whether you need one and have your potassium checked, especially if your kidneys are not working at full capacity or you take other medicines that raise potassium.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Hypercalcaemia risk
Caution Does Calcium interact with Digoxin?
A calcium supplement can raise blood calcium, and a high calcium level makes the heart more sensitive to digoxin, which already has a narrow safe range. Modest calcium doses with normal blood calcium are not expected to be a problem, but larger calcium intake, or calcium taken with high-dose vitamin D, is worth discussing with your prescriber so your calcium and digoxin can be kept in check.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Vitamin D3 interact with Digoxin?
High-dose vitamin D can raise blood calcium, and a high calcium level makes the heart more sensitive to digoxin, which already has a narrow safe range. Standard replacement doses of vitamin D with normal calcium are not expected to be a problem, but high-dose vitamin D, or vitamin D plus calcium supplements, is worth discussing with your prescriber so your calcium and digoxin can be kept in check.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Narrow-therapeutic-index prescriber awareness
Caution Does Bacopa Monnieri interact with Digoxin?
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 digoxin, which is usually taken for atrial fibrillation or heart failure, 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 Tongkat Ali interact with Digoxin?
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 digoxin, which is usually taken for atrial fibrillation or heart failure, 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.
P-glycoprotein induction (lowers drug levels)
Caution Does St John's Wort interact with Digoxin?
St John's Wort tends to reduce how much digoxin reaches your bloodstream, which may make it less effective at the prescribed dose. Because digoxin has a narrow safe range, do not start or stop St John's Wort while on digoxin without telling whoever prescribes it, so your dose and levels can be checked.
Evidence: Supported by human study data.
P-glycoprotein inhibition (raises drug levels)
Caution Does Berberine interact with Digoxin?
Berberine may raise digoxin blood levels by slowing how the gut pumps it back out. Digoxin has a narrow safe range, so if you take both, watch for nausea, visual changes or an irregular pulse and ask your GP whether a digoxin level check is worthwhile.
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 Quercetin interact with Digoxin?
Quercetin may slow how the body clears digoxin by blocking a transporter pump (P-glycoprotein), which can push digoxin levels higher. Digoxin has a narrow safe range, so if you take it, speak to your GP before adding quercetin and do not start a high-dose supplement without that conversation.
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.
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