warfarin
46 interactions related to warfarin
Warfarin + Vitamin K
Warfarin and vitamin K have directly opposing effects on blood clotting. Warfarin works by interfering with how the liver recycles vitamin K, so changes in vitamin K intake can push warfarin's effect up or down and alter the INR.
vitamin d + vitamin k2
Vitamin D and vitamin K2 act synergistically on calcium metabolism: vitamin D increases calcium absorption while vitamin K2 activates osteocalcin and matrix Gla protein to direct calcium into bone and away from soft tissue. The main caution is for people taking warfarin.
warfarin + dong quai
Dong quai (Angelica sinensis) contains coumarin-family compounds (ferulic acid, osthole) and has antiplatelet activity in laboratory studies. A published case report described a previously stable warfarin patient whose INR climbed well above her target range within weeks of adding dong quai, then returned to normal after she stopped it. The signal rests on a single human case plus animal data, so it is taken seriously but is not extensively documented.
warfarin + danshen
Danshen (Salvia miltiorrhiza), widely used in traditional Chinese medicine for cardiovascular conditions, interacts with warfarin on two fronts. It slows warfarin's clearance (a pharmacokinetic effect that raises warfarin levels) and independently inhibits platelets and clotting (a pharmacodynamic effect). Published case reports describe severe over-anticoagulation and serious bleeds, including bleeding into the chest cavity, when patients added danshen to warfarin.
warfarin + feverfew
Feverfew (Tanacetum parthenium) inhibits platelet aggregation in laboratory studies via its parthenolide sesquiterpene lactones, which creates a theoretical, additive bleeding concern alongside warfarin. The evidence is bench/in-vitro only: systematic reviews classify feverfew's anticoagulant signal as low-level laboratory evidence, and there are no published human case reports of bleeding when feverfew is combined with warfarin. The cautious, mechanism-based approach is to avoid concentrated feverfew supplements while on warfarin and to disclose use to the clinician managing anticoagulation.
parsley + warfarin
Fresh parsley is exceptionally vitamin K-dense; in cup-sized portions it provides a vitamin K load that can lower the INR in people on warfarin, reducing anticoagulation. The clinical effect depends on portion size and consistency.
green tea + warfarin
Green tea leaves contain vitamin K, the cofactor the liver needs to make the clotting factors warfarin works against. Large or fluctuating green tea intake can lower the INR and weaken warfarin's anticoagulant effect, as documented in a published case report. Moderate, steady intake is generally not a problem.
alcohol + warfarin
Alcohol affects warfarin in two opposing directions: acute heavy drinking slows the liver's metabolism of warfarin, which can raise INR and bleeding risk, while sustained heavy drinking induces those same enzymes and can lower INR, increasing clot risk. Alcohol also impairs platelets and can damage the liver where clotting factors are made, and intoxication raises fall risk, all of which compound the bleeding hazard.
warfarin + ginger
Ginger has a mild antiplatelet effect that can add to warfarin's anticoagulant effect. Case reports describe a rise in INR after a person on stable warfarin started a daily ginger supplement, with the INR returning to range once the supplement was stopped. Ginger used in cooking and the occasional ginger tea is a food-level exposure and is generally considered safe.
blood thinner + vitamin e
High-dose vitamin E supplements can add to the bleeding risk of anticoagulant and antiplatelet medications by inhibiting platelet aggregation and antagonizing vitamin K–dependent clotting factors.
warfarin + ginkgo
Warfarin and ginkgo act on clotting through different pathways, raising a plausible but not firmly proven bleeding concern.
warfarin + turmeric
Curcumin, the main active in turmeric, has antiplatelet activity that can add to warfarin's effect and raise bleeding risk. New Zealand's medicines regulator, Medsafe, issued an alert in 2018 after a patient stable on warfarin had their INR climb to a dangerously high level within weeks of starting a turmeric/curcumin product. A possible effect on the enzyme that clears warfarin has been seen only in animal and laboratory studies, not in people.
mustard greens + warfarin
Mustard greens are a dark leafy green that is very high in vitamin K1, the nutrient warfarin works against. Because warfarin blocks the recycling of vitamin K needed to make clotting factors, large or fluctuating intake of mustard greens can blunt warfarin's effect and lower your INR, while abruptly stopping a long-standing habit can push it up.
matcha + warfarin
Matcha is powdered whole green tea leaf, so each serving delivers more vitamin K than a brewed cup of green tea. Vitamin K is the cofactor warfarin works against, so starting, stopping, or varying a matcha habit can shift your INR and change how well warfarin protects you. The effect is documented for green tea and extends to matcha through its whole-leaf vitamin K content.
cranberry + warfarin
Cranberry contains flavonoids and polyphenols that may slow CYP2C9, the liver enzyme that clears the more potent S-enantiomer of warfarin. Multiple human case reports describe a rising INR and serious bleeding in patients who took up cranberry juice or supplements while stably anticoagulated, and the effect appears to depend on how much cranberry is consumed: randomized trials using a modest daily amount have not consistently reproduced it.
noni juice + warfarin
Noni juice (Morinda citrifolia) products vary widely in vitamin K content, and one published case of warfarin resistance was attributed to a high-vitamin K noni preparation. Noni has also been linked to drug-induced liver injury, which can secondarily destabilize warfarin. The interaction is real but rests on case reports rather than large studies.
collard greens + warfarin
Collard greens are one of the most vitamin-K-dense vegetables in the diet. Because warfarin works by blocking vitamin K, sudden increases or decreases in how much you eat can push your INR out of its therapeutic range. The goal is consistency, not avoidance.
spinach + warfarin
Spinach is one of the most concentrated dietary sources of vitamin K1, the very nutrient warfarin works against. Eating a lot of spinach, or suddenly changing how much you eat, can shift your INR out of its target range.
turnip greens + warfarin
Turnip greens are one of the most vitamin-K-rich vegetables on the table. Because warfarin works by blocking vitamin K-dependent clotting, large or fluctuating servings of turnip greens can blunt warfarin's effect and pull the INR below the therapeutic range, raising clot risk. The problem is inconsistency, not the food itself.
cayenne + warfarin
Capsaicin, the active constituent in cayenne (Capsicum), is theorized to add modestly to warfarin's blood-thinning effect through additive antiplatelet activity and possible effects on drug metabolism. The interaction is mechanistic; no human bleeding cases specific to cayenne plus warfarin have been documented, and interaction databases classify it as minor.
romaine + warfarin
Romaine lettuce is a moderate source of vitamin K1 (phylloquinone) - lower than dark cooking greens but meaningful at multi-cup salad servings. Large daily salads or romaine-heavy juices can supply enough vitamin K to oppose warfarin and nudge the INR downward. The risk is in changing your romaine habit, not in eating it.
cinnamon + warfarin
Concentrated cassia cinnamon supplements are a major source of coumarin, a compound that can be hard on the liver and may interfere with how the body clears warfarin. Because warfarin has a very narrow safety margin, even small shifts can raise bleeding risk, and case reports describe elevated INR when cinnamon-containing products were added to stable warfarin therapy.
microgreens + warfarin
Microgreens are the immature seedlings of vegetables and herbs, harvested when the first true leaves emerge. On a per-gram basis they concentrate vitamin K1 (phylloquinone), the form found in green plants that directly opposes warfarin. Brassica-family and amaranth microgreens are highest. A garnish-sized sprinkle is usually trivial, but daily salad-sized or smoothie portions are a meaningful vitamin K source that can shift the INR.
fenugreek + warfarin
Fenugreek (Trigonella foenum-graecum) contains coumarin-related compounds and has shown anticoagulant activity in laboratory studies. A published case report describes a rise in INR when a boldo-fenugreek combination product was added to stable warfarin therapy, with INR normalizing on discontinuation and rising again on rechallenge. The evidence is limited to that single case plus mechanistic plausibility, so the interaction is treated as plausible rather than firmly established.
psyllium + warfarin
Psyllium is a soluble fiber that forms a viscous gel in the gut, and it was long suspected of trapping warfarin and slowing its absorption. However, the limited human evidence available — a pharmacokinetic study and the monographs that cite it — found that psyllium does not measurably change warfarin's blood levels or its effect on the INR. Because warfarin has a narrow safety margin, keeping fiber intake steady and spacing the doses remains sensible, but a clinically meaningful interaction has not been demonstrated.
flax seeds + warfarin
Flax seeds contain alpha-linolenic acid (a plant omega-3) and soluble fiber, which in theory could nudge warfarin's effect slightly in either direction. In practice the evidence is weak: major interaction databases list no formal flaxseed-warfarin interaction, and the only adverse report is a single confounded case in a patient taking several other supplements. The practical concern is consistency, not the food itself.
chia seeds + warfarin
Chia seeds are rich in the omega-3 fatty acid alpha-linolenic acid (ALA) and in soluble fiber. High, sustained omega-3 intake can mildly inhibit platelet aggregation and may modestly add to warfarin's effect, while the soluble fiber can slow warfarin absorption if the two are taken together. Rare case reports describe enhanced anticoagulation or bleeding with chia and related Salvia species. The practical concern is dietary consistency rather than any single serving.
turmeric tea + warfarin
Curcumin, the main active compound in turmeric, has antiplatelet and anticoagulant activity in laboratory studies and may inhibit the liver enzymes that clear warfarin. Regulatory case reports describe stable warfarin patients whose INR rose into a dangerous, emergency range within weeks of starting a turmeric product. The published evidence is limited to a small number of case reports, but the bleeding signal is consistent enough to warrant caution.
broccoli + warfarin
Broccoli is one of the most vitamin K1 (phylloquinone)-rich common vegetables, and vitamin K is the cofactor warfarin works by blocking. It is not about avoiding broccoli but about consistency: large swings in intake can move your INR and reduce warfarin's effect or raise bleeding risk.
chamomile tea + warfarin
Chamomile contains naturally occurring coumarin-type compounds and may slow the liver enzymes that clear warfarin, so heavy or sudden chamomile use could add to warfarin's blood-thinning effect. A published case report linked frequent chamomile tea and lotion use to a dangerously high INR and severe internal bleeding in an older woman whose warfarin had previously been stable.
sauerkraut + warfarin
Sauerkraut is fermented green cabbage and is a moderate source of vitamin K1, the nutrient that warfarin works against. Because vitamin K supplies the cofactor for the very clotting factors warfarin blocks, suddenly starting, stopping, or swinging your sauerkraut intake can shift your INR and loosen anticoagulation control. The goal on warfarin is consistent intake, not avoidance.
flaxseed + warfarin
Flaxseed is rich in alpha-linolenic acid, an omega-3 fat with a mild antiplatelet effect, and in soluble fiber that can theoretically bind oral medicines in the gut. Both mechanisms could in principle nudge warfarin's bleeding risk or absorption, but no case of an actual flaxseed-warfarin bleed or INR shift has been documented. The concern is mechanistic and the practical risk from culinary amounts is low.
brazil nuts + warfarin
Brazil nuts contain essentially no vitamin K, so they do not antagonize warfarin or destabilize INR the way leafy greens can. Their notable feature is a very high selenium content, but selenium has no established effect on how warfarin works or is metabolized. The only practical reason to keep brazil nuts modest is selenium safety, not anticoagulation.
walnuts + warfarin
Walnuts contain only trace amounts of vitamin K and small quantities of plant-based omega-3 (alpha-linolenic acid). Normal food servings are unlikely to meaningfully shift INR. The standard warfarin principle applies: keep your intake reasonably consistent rather than swinging between none and very large daily portions.
cocoa + warfarin
Cocoa flavanols can modestly reduce platelet activity in people, which in theory could add to warfarin's anticoagulant effect. In practice the evidence is mechanistic only: no case reports or clinical studies show actual bleeding or a change in INR from cocoa in people taking warfarin. Keeping cocoa intake small and consistent is a sensible precaution rather than a response to a proven interaction.
fluconazole + warfarin
Fluconazole inhibits CYP2C9, the main enzyme that clears warfarin, so it can sharply raise warfarin's blood-thinning effect within a few days of starting, even after a single antifungal dose. Case reports document this combination causing serious and sometimes fatal bleeding.
pomegranate + warfarin
Pomegranate contains punicalagins and other polyphenols that inhibit the liver enzymes CYP2C9 and CYP3A4 in laboratory and animal studies, which would slow warfarin metabolism. Case reports describe both a raised INR after heavy or newly started pomegranate juice intake and a falling INR after stopping a habitual juice habit. The effect appears to be genuine but infrequent, and consistency of intake matters more than total avoidance.
sesame seeds + warfarin
Sesame seeds contain lignans (chiefly sesamin) that, in laboratory studies, inhibit a liver enzyme that clears warfarin. The concern is mechanistic and comes from test tubes, not from people who have been harmed.
swiss chard + warfarin
Swiss chard is a high-vitamin-K leafy green, and warfarin works by blocking vitamin K. Large, sudden swings in how much chard you eat can move your INR out of range, but the interaction is manageable: the goal is steady, consistent intake rather than avoidance.
pumpkin seeds + warfarin
Pumpkin seeds (pepitas) are a low-vitamin-K food and do not meaningfully affect warfarin in normal snack portions. The general warfarin principle of keeping vitamin-K intake consistent still applies, but pumpkin seeds are not a notable source.
kimchi + warfarin
Kimchi is fermented Napa cabbage and contains vitamin K1, the cofactor warfarin works against. Inconsistent kimchi intake can shift your INR and change warfarin's effect. The problem is not the food but the swings in how much you eat.
cbd + warfarin
CBD inhibits the liver enzymes (notably CYP2C9, and also CYP3A4) that clear warfarin, especially its more potent S-enantiomer. Adding CBD to a stable warfarin regimen can slow warfarin breakdown, raise its blood level, push the INR upward, and increase bleeding risk. A published case report described a patient who needed a meaningful warfarin dose reduction after starting CBD.
chia seeds + blood thinners
Chia seeds contain plant-form omega-3 (alpha-linolenic acid) and soluble fiber. The omega-3 has a mild, mostly theoretical effect on platelets, and the fiber gel could slow a pill's absorption if eaten at the same time. There is no documented case of chia seeds themselves causing bleeding on warfarin, DOACs, aspirin, or antiplatelet drugs, and human studies of dietary omega-3 do not show added bleeding. The anticoagulant caution often cited comes from a different plant (danshen root), not chia.
warfarin + fish oil
Fish oil may modestly add to bleeding risk when combined with warfarin, though most people on stable doses show little change in INR.
hemp seeds + warfarin
Plain culinary hemp seeds (hulled or whole) contain only trace cannabinoids and little vitamin K, so they are unlikely to meaningfully change how warfarin works. The real concern is product confusion: anything labelled hemp extract, full-spectrum hemp, or CBD is a different category and can slow warfarin breakdown via the CYP2C9 enzyme, raising INR and bleeding risk.
warfarin + garlic
Concentrated garlic supplements may add to warfarin's blood-thinning effect, mainly through a mild antiplatelet action, though the clinical evidence for important bleeding is weak.