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 warfarin directly. CYP2C9 inhibitors raise warfarin plasma levels and push INR up. 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 14 documented pairs we have explicitly assessed against Acenocoumarol in the Distil database: 2 red and 12 amber. 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
CYP induction
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Panax ginseng has been reported to reduce the effect of vitamin-K-based blood thinners like acenocoumarol, which could lower your INR and reduce protection against clots. If you take acenocoumarol, discuss ginseng with your anticoagulant clinic and keep your INR monitored rather than starting it on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Vitamin K pathway
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.
Coenzyme Q10 is structurally similar to vitamin K and may slightly reduce the effect of acenocoumarol, a vitamin-K-based 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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Green tea contains vitamin K, which can work against acenocoumarol, a vitamin-K-based blood thinner, and changing how much you drink can swing your INR. Large or fluctuating intakes are the concern. If you take acenocoumarol, keep green tea intake steady and tell your anticoagulant clinic.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive anticoagulation
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
L-carnitine has been reported in a few cases to increase the effect of vitamin-K-based blood thinners like acenocoumarol, raising the INR. The evidence is limited. If you take acenocoumarol and use L-carnitine, mention it to your anticoagulant clinic and have your INR checked.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Reduced anticoagulant effect
Very high doses of vitamin C have been linked in rare reports to a reduced effect of vitamin-K-based blood thinners like acenocoumarol, which could lower your INR. Normal vitamin C intake is not a concern. If you take acenocoumarol and use high-dose vitamin C, keep it steady and mention it to your anticoagulant clinic.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive antiplatelet effect
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
High-dose vitamin E can mildly reduce blood clotting, which may add to the blood-thinning effect of acenocoumarol and raise bleeding risk. The concern is with high supplemental doses. If you take acenocoumarol, keep vitamin E intake modest and tell your anticoagulant clinic.
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.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyWant this reasoning across everything you take?
This page checks the pairs you enter. A personalised Distil report applies the same graded, cited reasoning to your whole stack: your goals, conditions, medications, diet, and the compounds worth adding or dropping. The interactions check is one section of it. You can read a real one in full before you decide.
See a real sample reportSomething missing?
If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.