Herbs that interfere with Coumadin

4 Jan


Your seemingly medication compliant patient on coumadin presents to your ER because they are bleeding inconveniently from somewhere they would prefer not to bleed from.  They mention to you offhand that the have been using a variety of herbal remedies for a recent URI.  Could this be the culprit?


Documented human interactions with Coumadin:

Coenzyme Q is structurally similar to vitamin K

Danshen decreases platelet aggregation

Devil’s claw– unknown interaction mechanism but a case of purpura has been documented.

Dong Quai inhibits platelet aggregation

Ginseng antagonizes anticoagulant effect of Coumadin

Green Tea large amounts may antagonize Coumadin

Papain unknown interaction mechanism but has been a documented case of elevated INR

Vitamin E affect on coagulation cascade specifically vitamin K dependent factors.


Also possible interactions, although no documented case reports:

Meadowsweet, poplar, and willow bark contain high concentrations of salicylates,

bromelain, clove, onion, and turmeric have been reported to exhibit antiplatelet activity.

Borage seed oil contains glinoleic acid, which may increase coagulation time.

Bogbean has been noted to demonstrate hemolytic activity,

capsicum has been reported to cause hypocoagulability.

Sweetclover has shown to cause hemorrhagic deaths in CATTLE! But not in humans.

Herbs thought to contain coumarin (precursor molecule to coumadin) or coumarin derivatives include: angelica root, arnica flower, anise, asafoetida, celery, chamomile, fenugreek, horse chestnut, licorice root, lovage root, parsley, passionflower herb, quassia, red clover, and rue.


Submitted by J. Rothstein.


References: medscape article, picture


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