Supplements and Acenocoumarol.
Acenocoumarol, sold under the brand name Sinthrome, is a vitamin-K antagonist anticoagulant. It sits in a narrow therapeutic window monitored by INR.
Acenocoumarol is a vitamin K antagonist anticoagulant. The class is gradually being replaced by DOACs (apixaban, rivaroxaban, edoxaban) for atrial fibrillation, but remains in active UK prescribing for mechanical heart valves, antiphospholipid syndrome, and where DOAC contraindications apply. The defining feature is the narrow therapeutic window. INR is measured regularly because under-treatment leaves stroke risk on the table, while excess anticoagulation drives bleeding. The supplement surface is one of the largest in clinical pharmacology. Vitamin K opposes the drug directly. Most of the rest of the signal is additive antiplatelet, clot-dissolving or anticoagulant effect rather than a change in drug levels, which is where garlic, ginkgo, high-dose fish oil and nattokinase sit. Curcumin sits there too, with a weak CYP2C9 effect on top. CYP induction by St John's Wort drops INR. That combination is hard excluded. Any supplement decision belongs with the anticoagulant clinic.
Below are the 23 documented pairs we have explicitly assessed against Acenocoumarol in the Distil database: 2 severe and 21 caution. The pairs cluster around 5 mechanisms: CYP induction, Vitamin K pathway, Additive anticoagulation, Reduced anticoagulant effect, and Additive antiplatelet effect. 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 12 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.
CYP induction
Severe Does St John's Wort interact with Acenocoumarol?
St John's Wort speeds up how the body clears acenocoumarol, which can make the blood thinner much less effective and dangerously raise the risk of a clot. This is a serious interaction. Do not take St John's Wort with acenocoumarol, and if you already take both, tell your anticoagulant clinic before stopping either.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Panax Ginseng interact with Acenocoumarol?
Ginseng may work against warfarin-type blood thinners like acenocoumarol and lower your INR, which would reduce protection against clots. The evidence is mixed between ginseng types: the trial that found an INR reduction used AMERICAN ginseng, and a separate trial of Asian Panax ginseng found no effect on warfarin at all. If you take acenocoumarol, discuss ginseng with your anticoagulant clinic and keep your INR monitored rather than starting it on your own.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Vitamin K pathway
Severe Does Vitamin K2 interact with Acenocoumarol?
Vitamin K2 directly opposes acenocoumarol, which is a blood thinner that works by blocking vitamin K. Taking K2 can make acenocoumarol less effective and raise the risk of a clot, and changing your K2 intake can swing your INR test result. If you take acenocoumarol, do not start or stop vitamin K2 without your anticoagulant clinic's guidance, and keep your intake steady.
Evidence: Supported by human study data.
Caution Does Coenzyme Q10 interact with Acenocoumarol?
Coenzyme Q10 is structurally similar to vitamin K and may slightly reduce the effect of acenocoumarol, a warfarin-type blood thinner, which could lower your INR. The signal is weak and comes from reports with the related drug warfarin. If you take acenocoumarol, keep your CoQ10 intake steady and mention it to your anticoagulant clinic so your INR can be watched.
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.
Additive anticoagulation
Caution Does Andrographis interact with Acenocoumarol?
Andrographis may raise the effect of acenocoumarol, both by a mild blood-thinning action of its own and by slowing how the body clears the drug. The direct evidence is from animal studies with a similar anticoagulant rather than from people taking acenocoumarol. If you take acenocoumarol, tell your anticoagulation clinic before starting andrographis and ask for an INR check a couple of weeks in.
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 Bromelain interact with Acenocoumarol?
Bromelain has a mild blood-thinning effect that may add to acenocoumarol's. If you take acenocoumarol, tell whoever monitors your INR before adding bromelain and check your INR if you do. If you have surgery planned, mention bromelain to your team; stopping high-dose bromelain about two weeks beforehand is a common precaution.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Cordyceps interact with Acenocoumarol?
Cordyceps may add to acenocoumarol's blood-thinning effect through a mild anti-clotting action of its own. This is based on laboratory work on human platelets rather than studies in people taking acenocoumarol, so the real-world size of the effect is unknown. If you take acenocoumarol, mention cordyceps to your anticoagulation clinic and ask whether an INR check is worth doing after you start.
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 Cranberry Extract (PAC-standardised) interact with Acenocoumarol?
Cranberry can raise the effect of acenocoumarol, a blood thinner in the same family as warfarin, and push your INR up; with warfarin this was seen with large volumes of juice and, in a controlled trial, with capsules. The signal comes from the related drug warfarin rather than from acenocoumarol directly. If you take acenocoumarol, keep your cranberry intake steady rather than starting or stopping it suddenly, and tell your anticoagulant clinic so your INR can be watched.
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 Curcumin interact with Acenocoumarol?
Curcumin (from turmeric) can mildly reduce clotting, which may add to the blood-thinning effect of acenocoumarol. Cooking amounts of turmeric are not the concern; concentrated curcumin supplements are. If you take acenocoumarol, discuss curcumin with your anticoagulant clinic and watch for bruising or bleeding.
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 Fisetin interact with Acenocoumarol?
Fisetin may mildly thin the blood by reducing platelet clumping, which could add to warfarin-type blood thinners like acenocoumarol. The concern is with a high-dose fisetin course, not food amounts. If you take acenocoumarol, tell your anticoagulant clinic before starting a fisetin course and watch for bruising or bleeding.
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 Glucosamine interact with Acenocoumarol?
Glucosamine (often with chondroitin) has been reported to increase the blood-thinning effect of acenocoumarol and raise the INR, sometimes enough to cause bleeding. If you take acenocoumarol, it is best to avoid glucosamine or only use it with your anticoagulant clinic's knowledge and extra INR checks.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does L-Carnitine interact with Acenocoumarol?
Two published case reports describe L-carnitine making acenocoumarol, a warfarin-type blood thinner, work more strongly. In the more recent one, from 2004, a man with a mechanical heart valve saw his INR rise to 4.65 while he took 1,000mg of L-carnitine a day, and it settled back into his usual range after he stopped. That is still thin evidence, but if you take acenocoumarol and use L-carnitine, mention it to your anticoagulant clinic and have your INR checked.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Pine Bark Extract interact with Acenocoumarol?
Pine bark extract (pycnogenol) has a mild blood-thinning effect of its own, shown in people as reduced platelet stickiness, mainly in smokers. It has not been studied alongside acenocoumarol, so the size of any combined effect is unknown. If you take acenocoumarol, tell your anticoagulation clinic before starting pine bark extract and ask for an INR check a couple of weeks in.
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 Acenocoumarol?
High-dose quercetin may mildly add to the blood-thinning effect of acenocoumarol. The signal is weak. If you take acenocoumarol and use quercetin supplements, mention it to your anticoagulant clinic and watch for bruising.
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 Resveratrol interact with Acenocoumarol?
Resveratrol can both slow how the body clears warfarin-type blood thinners like acenocoumarol and mildly thin the blood by reducing platelet clumping, which could push your INR up. Food amounts are not the concern; concentrated supplements are. If you take acenocoumarol, tell your anticoagulant clinic before starting resveratrol and watch for bruising or bleeding.
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 Spirulina interact with Acenocoumarol?
Spirulina has a mild antiplatelet signal in laboratory studies, but a human trial at a high dose found no change in clotting tests or platelet activity. Any effect on acenocoumarol is likely to be small. If you take acenocoumarol, keep your spirulina intake steady rather than starting or stopping suddenly, and tell your anticoagulation clinic what you take.
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.
Reduced anticoagulant effect
Caution Does Collagen Precursors interact with Acenocoumarol?
The 1,000 mg of vitamin C in this collagen precursor blend (a high daily dose) may reduce the effect of warfarin-type blood thinners like acenocoumarol, which could lower your INR; vitamin C supplements, one at 200 mg twice a day, have been linked to this with warfarin in rare reports. If you take acenocoumarol, keep this blend steady and mention it to your anticoagulant clinic.
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 Green Tea Extract interact with Acenocoumarol?
Very large amounts of green tea have been reported to work against warfarin, a close relative of acenocoumarol, lowering the INR, and changing how much you drink may swing yours. Why is not settled, since brewed tea carries very little vitamin K. Large or fluctuating intakes are the concern. If you take acenocoumarol, keep green tea intake steady and tell your anticoagulant clinic.
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 Vitamin C interact with Acenocoumarol?
Vitamin C supplements have been linked in rare reports to a reduced effect of warfarin-type blood thinners like acenocoumarol, which could lower your INR. In one of those reports the person was taking 200 mg twice a day, an ordinary supplement dose, so we cannot point to a level below which it stops applying. Vitamin C from food is not the concern. If you take acenocoumarol and use a vitamin C supplement, keep the dose steady and mention it to your anticoagulant clinic.
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.
Additive antiplatelet effect
Caution Does Garlic Extract interact with Acenocoumarol?
Garlic supplements can thin the blood by reducing how well platelets clump, which adds to the blood-thinning effect of acenocoumarol and may raise bleeding risk. Culinary amounts of garlic are not the concern; concentrated extracts are. If you take acenocoumarol, discuss garlic supplements with your anticoagulant clinic and watch for easy bruising or bleeding.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Ginkgo Biloba interact with Acenocoumarol?
Ginkgo can reduce platelet stickiness, which adds to the blood-thinning effect of acenocoumarol and may raise the risk of bleeding. If you take acenocoumarol, discuss ginkgo with your anticoagulant clinic and watch for unusual bruising or bleeding.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Omega-3 EPA interact with Acenocoumarol?
High-dose fish oil (omega-3) can mildly reduce platelet stickiness, which may add to the blood-thinning effect of acenocoumarol. The effect is usually small at typical doses. If you take acenocoumarol and use high-dose omega-3, mention it to your anticoagulant clinic and watch for easy bruising.
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 Vitamin E interact with Acenocoumarol?
High-dose vitamin E can mildly reduce blood clotting, which may add to the blood-thinning effect of acenocoumarol and raise bleeding risk. The one trial in this drug family, with warfarin, found no change in INR, but it did not count bleeding events, so a lower dose cannot be assumed to be free of the concern. Tell your anticoagulant clinic before taking vitamin E at any dose, and stop it at least two weeks before planned surgery.
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.
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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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