coumadin
12 interactions related to coumadin
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.
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.
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.
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.
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.
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.
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.