Warfarin (Coumadin) is an anticoagulant used to thin the blood and prevent it from clotting. It is a somewhat dangerous drug that can be affected by many substances, including food. Note : If you are taking warfarin, we do not recommend taking any herb or supplement except on a physician's advice.
Similar blood-thinning drugs are anisindione (Miradon) and dicumarol.
The herb alfalfa (Medicago sativa) is promoted for a variety of conditions. The relatively high vitamin K content in alfalfa could reduce the effectiveness of warfarin. Vitamin K directly counteracts warfarin's blood-thinning effects. Since the amount of vitamin K in alfalfa varies widely, it is difficult to give an exact safe upper dose.
As a precaution, avoid alfalfa supplements during warfarin therapy except under medical supervision.
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The herb danshen, the root of Salvia miltiorrhiza, is used in traditional Chinese medicine for treating heart disease.
Therefore, if you take warfarin, you should avoid danshen except under a physician's supervision.
The herb devil's claw ( Harpogophytum procumbens ) is used for various types of arthritis and digestive problems.
As a precaution, you should probably not combine devil's claw and warfarin except under a physician's supervision.
The herb dong quai ( Angelica sinensis ) is used for menstrual disorders.
You should probably avoid combining dong quai and warfarin without medical supervision.
The herb feverfew ( Tanacetum parthenium ) is primarily used for the prevention and treatment of migraine headaches.
Though an additive effect of feverfew and warfarin appears to be theoretical at this time, it may be best to avoid this combination except under medical supervision.
The herb garlic (Allium sativum) is taken to lower cholesterol, among many other proposed uses.
Based on these findings, you should avoid combining garlic and warfarin except under a physician's supervision.
The herb ginger ( Zingiber officinale ) is used for nausea associated with motion sickness, morning sickness in pregnancy, and the postsurgical period.
Though an additive effect of ginger and warfarin appears to be theoretical based on current evidence, it may be best to avoid this combination except under medical supervision. Ginger flavored drinks should not present a problem, but candies containing whole dried ginger are potentially of concern.
The herb ginkgo ( Ginkgo biloba ) has been used to treat Alzheimer's disease and ordinary age-related memory loss, among many other uses.
Ipriflavone, a synthetic isoflavone that slows bone breakdown, is used to treat osteoporosis.
If you try this combination, you need to do so under physician supervision.
Policosanol, derived from sugarcane, is used to reduce cholesterol levels. It also interferes with platelet clumping, creating a risk of interactions with blood-thinning drugs.
Based on these findings, you should not combine warfarin and policosanol except under medical supervision.
The herb St. John's wort ( Hypericum perforatum ) is primarily used to treat mild to moderate depression.
A "hidden" risk lies in this type of interaction. Suppose your physician has raised the warfarin dose to take into account the effect of St. John's wort in holding down drug levels. If you then stop taking the herbal product, it would be like releasing the brakes, and your warfarin levels could surge dangerously high.
For these reasons, if you take warfarin, avoid St. John's wort except under a physician's supervision.
For this reason, it may be best to avoid combining vitamin A with warfarin unless supervised by a physician.
As a precaution, if you take warfarin, consult with your physician before taking high-dose vitamin C supplements.
Though the evidence supporting a possible interaction is scanty, it is best not to risk serious bleeding problems. Avoid combining vitamin E with warfarin except under the supervision of a physician.
Therefore, once you are established on a certain dose of warfarin, you should not change your usual intake of vitamin K without informing your physician.
The herb white willow ( Salix alba ), also known as willow bark, is used to treat pain and fever. White willow contains a substance that is converted by the body into a salicylate similar to the blood-thinner aspirin.
Because white willow, like aspirin, may enhance the blood-thinning effects of warfarin, this combination should be avoided unless medically supervised.
Based on their known effects or the effects of their constituents, the following herbs and supplements might not be safe to combine with warfarin, though this has not been proven: chamomile ( Matricaria recutita ), Coleus forskohlii , ginger ( Zingiber officinale ), horse chestnut ( Aesculus hippocastanum ), papaya ( Carica papaya ), red clover ( Trifolium pratense ), and reishi ( Ganoderma lucidum ); mesoglycan , fish oil , oligomeric proanthocyanidins (OPCs), and phosphatidylserine .
- Reviewer: EBSCO CAM Review Board
- Review Date: 08/2013 -
- Update Date: 08/22/2013 -