Coumadin, the brand name for the blood-thinning drug warfarin, slows blood clotting. It is prescribed for patients with blood clots and those with certain kinds of heart conditions. A number of herbs can interact with Coumadin and can increase or decrease the drug's effects. Patients should consult with their doctors before starting or stopping herbal products while taking Coumadin.
Coumadin
Coumadin is one several anticoagulant medications that prevent blood clots from forming or keep them from getting bigger. Doctors prescribe Coumadin to treat blood clots in the legs and lungs. The medication also treats a type of irregular heartbeat known as atrial fibrilation and is taken by people who have had heart valve replacement and those who have had a heart attack. Coumadin is usually taken once a day. However, its blood thinning properties can lead to serious bleeding problems that are more likely to occur in those taking higher doses or when first starting the medication, according to its manufacturer Bristol-Myers Squibb. In addition to avoiding certain herbal medicine, patients should not eat large amounts of foods containing vitamin K while taking the drug.
Herbs That May Increase Bleeding
Many herbs thin the blood and can make Coumadin's effects stronger. This could lead to slowed blood clotting and excessive bleeding. Increased bruising may also occur. Herbs that might exacerbate Coumadin's effects include ginger, flaxseed, horse chestnut, billberry, devil's claw, German chamomile, Roman chamomile, willow bark, red clover, garlic, dong quai, celery seed and turmeric, according to the National Institutes of Health.
Herbs That Decrease Effectiveness
A number of herbs may reduce the effectiveness of Coumadin by decreasing its absorption in the body. These include St. John's wort, used to treat depression and anxiety, as well as some lesser-used herbs, including marshmallow, European buckthorn, castor, Mexican scammony root, slippery elm and tragacanth, according to the University of Maryland Medical Center and the journal "Expert Opinion on Drug Safety".
Conflicting Reports
The jury is still out on taking ginkgo biloba and green tea with Coumadin. While the University of Maryland Medical Center reports that internal bleeding has occurred in some people taking ginkgo, there isn't a definitive link with Coumadin. Researchers are also unsure if green tea might interfere with the blood-thinning effects of Coumadin. Green tea might contain enough vitamin K to lower the drug's potency, according to "Expert Opinion on Drug Safety".
