Coumadin Interaction with herbs, vitamins, enzymes, food, diet restrictions and natural supplements, risks, and side effects
November 20 2016 by
Ray Sahelian, M.D.

Coumadin sodium is a compound that thins the blood and was originally used as rat poison. Coumadin treatment reduces the risk of thrombosis (blood clots), but makes patients more liable to bleeding, sometimes with serious consequences. Coumadin is effective at reducing the risk of stroke in atrial fibrillation. In the U.S., warfarin is sold under the trade name Coumadin.

Natural Supplements, vitamins, herbs and Coumadin, diet restriction
Certain supplements have blood thinning potential and should be used with caution by those who are on blood thinning medication such as Coumadin. These natural supplements include, in alphabetical order:

Bee pollen
Am J Health Syst Pharm. 2010. Probable interaction between Coumadin and bee pollen. Consumption of bee pollen led to increased INR values in a patient taking Coumadin.

Chamomile is a mild relaxation agent and has very mild blood thinning activity.
CoQ10 supplement has been associated with an increased risk of bleeding with the use of Coumadin medication.
Cranberry juice, sauce or cranberry supplements thin the blood and increase INR levels in patients who are taking Coumadin medication.
Dong quai is a Chinese herbal supplement which has natural coumarin derivatives. Dong quai increases the effect of Coumadin, increasing the risk of bleeding; therefore, co-administration of dong quai and Coumadin is contraindicated.
EGCG, the extract from green tea, may prevent platelet aggregation as potently as aspirin.
Fish oils thin the blood and their risk in combination with Coumadin depends on the dose of the fish oils and the dose of Coumadin. Krill oil also also has long-chained omega-3 fatty acids DHA and EPA and should be used with caution. Those who take fish oil pills may need to reduce their dose of prescription anti-coagulants since it is possible that the INR can increase with supplementation.
Cayenne supplement may increase the risk of bleeding with the use of Coumadin medication.
Garlic is a blood thinner. So are onions.
Ginger may increase bleeding risk in those who are taking Coumadin pills
Ginkgo biloba is an herb used for mental alertness that has some blood thinning potential. Bleeding episodes in patients taking Ginkgo biloba and Coumadin have been documented. Therefore, in vitro and in vivo inhibition studies were done to ascertain the influence of ginkgo on CYP2C9, the P-450 isozyme responsible for the metabolism of the most potent Coumadin enantiomer, (S)-Coumadin. Ginkgo extract inhibited human liver microsomal CYP2C9. Two open-label, crossover pharmacokinetic studies in healthy subjects were performed using tolbutamide and diclofenac as probe CYP2C9 substrates. In contrast to the in vitro inhibition of CYP2C9, no interactions between Ginkgo biloba extract and CYP2C9 probe substrates were observed in vivo as evidenced by the lack of effect on the steady-state pharmacokinetics of diclofenac or on the urinary metabolic ratio of tolbutamide.
Indole3Carbinol is a potent anti-thrombotic agent with anti-platelet activity.
Nattokinase is a potent blood thinner compared to other natural herbs and supplements. Always consult with your doctor before taking nattokinase blood thinner, particularly if you are taking Coumadin.
Onion has blood thinning potential
St Johns Wort herb may increase the risk for bleeding when used together with Coumadin medication.
White willow bark supplement.

Nat Prod Commun. 2014. Warfarin interactions with medicinal herbs. Potential herb-drug interactions are of a major safety concern, especially for drugs with narrow therapeutic indices like Coumadin, which can lead to severe adverse reactions that are sometimes life-threatening. The interactions between Coumadin and medicinal herbs described in the literature have been summarized in this paper relying on Medline database (via PubMed) using the key words: Coumadin, herbal supplements and interactions. The references on the analyzed literature have been investigated in order to collect the existing data. The case reports with severe adverse effects such as spontaneous postoperative bleeding, formation of hematomas, hematemesis, melena, thrombosis, subarachnoid hemorrhage and/or subdural hematomas after concomitant use of warfarin and the medicinal herbs: Panax ginseng, Hypericum perforatum, Salvia milthiorizza, Gingko biloba, Serenoa repens, Angelica sinensis, Vaccinium species, Allium sativum, Zingiber officinale, Tanacetum parthenium, Lucium barbarum, Matricaria chamomilla, Boswellia serrata and Camellia sinensis have been estimated. Some of the interactions between Coumadin and medicinal herbs have been well assessed proving that they are closely-dependent. The interactions between Coumadin and medicinal herbs, not generally reported in previous reviews, are presented in our review.

Q. My father is taking Coumadin due to heart problems and blood clots in his two legs. He also has gout. I have tried to research natural herbs to help him with his gout. Could you please let me know if certain herbs will interact with this blood thinner. He is taking tumeric rootyucca stalk extract banaba leaf extract acai fruit extract bicarbonate of soda milk thistle seed celery seed extract artichoke leaf extract.
   A. It is difficult to give specific recommendations since thorough research is not available on these herbs and their interactions.

Q. My husband is on Coumadin. Would vinpocetine interfere with this?
   A. Vinpocetine may have mild blood thinning potential, so it is difficult to know what the interaction would be. It may be a good idea to avoid vinpocetine with Coumadin until studies are done.

Q. Are there any contraindications for alpha lipoic acid being taken with Coumadin? I have DVT and have been on Coumadin for 3 months and wish to resume taking alpha lipoic acid.
   A. We have not come across such interaction between Coumadin and lipoic at this time, but we are not aware of any testing that has been done with these two together.

Coumadin bleeding risk
Risk factors significantly associated with increased bleeding included high target INR (2.5 to 3.5), diarrhea, acetaminophen use, alcohol consumption, and increased age.

Coumadin side effects, danger
Hemorrhage (bleeding) is one of the most common and serious risk associated with coumadin therapy. The bleeding can occur in practically any tissue or organ. The signs, symptoms and severity of the bleeding and subsequent complicationsl vary according to the location and degree of bleeding. Haemorrhagic complications may present as headache, hypotension, chest, abdomen and muscle pain, red blood in stools or black stool. Other side effects of coumadin therapy are necrosis of the skin or skin rashes, priapism, headache, and dark urine.

The long-term use of Coumadin appears to increase the risk of fractures associated with osteoporosis, a bone-thinning condition that usually increased with age. Coumadin prevents coagulation by blocking vitamin K, which is needed to activate certain clotting factors. Because vitamin K is also used to activate proteins involved in bone formation, drugs like coumadin may increase the risk of fractures. To investigate, Dr. Brian F. Gage, from Washington University School of Medicine in St. Louis, and colleagues assessed the rate of osteoporotic fractures among 12,048 Medicare beneficiaries. The subjects included 4,461 who had been prescribed Coumadin for at least one year and 7,587 who were not on the drug. Coumadin users were 25 percent more likely to experience a fracture than nonusers. However, this relationship was statistically significant only in men. Further analysis of data from 1,833 patients who were on Coumadin for less than one year did not detect a statistically significant increase in fracture risk. Risk factors for fracture included older age, high risk of falling, overactive thyroid, neurological or psychiatric disorders, and alcoholism, the report notes. When prescribing Coumadin to elderly patients at high risk of falling, healthcare providers can instruct them to wear stable shoes, exercise regularly, have adequate intake of calcium and vitamin D, use walking aids, and discontinue unnecessary medications. Archives of Internal Medicine, 2006.

Coumadin diet interaction, restricitons
The effect of coumadin decreases after initiation of a high-protein, low-carbohydrate diet.

Coumadin alcohol interaction
It's quite likely that alcohol interferes with its metabolism and effect. Hence, it is preferable to avoid drinking more than one glass of alcohol a day. Wine has compounds called flavonoids that thin the blood.

Coumadin drug interaction
Non-selective non-steroidal anti-inflammatory drugs (nNSAIDs) used in combination with Coumadin are associated with an approximately 3-fold increased risk of upper gastrointestinal bleeding compared with Coumadin alone.

Q. Can you tell me if there are any contraindications between Passion Rx and Coumadin (warfarin)?
   A. We have not tested blood coagulation parameters with Passion Rx so we don't know if the herbs influence blood thinning or coagulation or have no effect. Most of the time coumadin or warfarin is taken by those who have a heart condition or atrial fibrillation, and we do not suggest people with a heart condition take Passion Rx or most of the sex herbs since they have a tendency to speed heart rate.

Q. i have ordered Prostate Power Rx caps, can you tell me if the herbs in it interfere with Coumadin / warfirin ?
   A.  So many factors are involved including the dose of your Coumadin, how you absorb and process herbs, your overall health condition, your liver function, etc. We suggest your doctor review the information on the ingredients in Prostate Power Rx and come to a decision, perhaps using only one capsule a day.

Q. My husband is interested in taking Inno-Vite Sytrinol to lower cholesterol, do you know of any interaction of Sytrinol with any medications, including Coumadin?
   A. This is so difficult to say since I have not seen studies testing Coumadin in combination with Sytrinol. Plus, much may depend on dosages and each person's unique absorption and metabolizing processes.

Q. I'm a journalist and read your newsletters which I really like. Can you tell me if there are natural supplements that can take the place of coumadin?
   A. Many supplements and herbs have blood thinning potential, but since I am not aware of head to head comparisons between herbs and Coumadin, and since blood thinning for A Fib or stroke prevention is quite a serious thing, it is difficult to make any definitive recommendations. Nattokinase appears to be one of the most potent natural blood thinners.

Q. I have been taking Coumadin for three years. I've been told that I have an unspecified blood disorder. This diagnosis came after many test by hematologist and after 3 different episode with DVTs. Is there a safe, long term natural supplement that I can take as an alternative to Coumadin. I am otherwise a healthy 47 year old male.
   A. Coumadin is a potent blood thinner and we are not aware of any supplements that are as potent as Coumadin. It is possible that a combination of several supplements may thin the blood enough to reduce the need for Coumadin or lower the Coumadin dose requirements, but this is a complicated area and medical supervision is required since if the supplements fail, a recurrence of deep vein thrombosis is of major concern.

Q. I am a 74 year old woman interested in natural supplements that can possibly prevent me from increasing my coumadin dosage and hopefully allow me to lower the dosage. My doctor has told me that I need to increase my
pro-time though I am already taking Coumadin 5mg 4 times/week and 2.5mg 3times/week. I have a mechanical heart valve, and have had two bypasses. I eat very healthfully and currently Coumadin is the only prescription I need. I am concerned about increasing the Coumadin because of side effects, such as bleeding and liver area pain, and long term side effects. I understand that this is a challenging physical condition, but I believe you would be more helpful than any other professional I have encountered. If I maintain a close to nature, organic diet, and safe supplements with
assistance to determine the best possible choices of foods, is it possible that I could lower or even discontinue the coumadin if I keep a close watch on my pro-time levels. In searching for blood thinners and blood purifiers, I have found suggestions of the following: (Could you please let me know which of these you could recommend or discourage.) I would be willing to pay a consultation fee, if you could please let me know what that charge would be. Vitamin E, Ginko Biloba, Fish Oils, Nattokinase, Chamomile, Bromelain, Feverfew, Dong Quai, Garlic, Ginger, Hawthorne, Others: Sardines, EGCG, onion, pineapple, organic fresh veggie juice, lecithin, tree ear mushrooms, pomegranet juice, alfalfa, barberry, brigham tea, chapparral, chlorophyll, dandelion, hyssop, licorice, myrrh, red clover, sarsaparilla, taheebo, yellow doc, lobelia, burdock, blue cohosh, black cohosh, couch grass, comfrey, spikenard, strawberry, yucca, yarrow, buckthorn, cascara sagrada, oregon grape, peach, prickly ash, stillingia. Could you please let me know if you see patients or if you can give me a referral to someone, a physician or health care provider, who could help me with natural treatments and diet? I live in the Brenham Texas area, halfway between Austin and Houston, TX.
   A. We understand fully your concern regarding potential Coumadin side effects and the urge to find natural solutions. However, Dr. Sahelian does not take new patients and we don't keep a doctor referral system. Most herbs and vegetables have blood thinning potential, so does aspirin. We really can't give any individual advice but can only give general research information on natural products that help with blood flow as listed above. It is possible that using these natural supplements may lower the required Coumadin dose, but we can't be more specific since we can't take over the role of your doctor.

Q. I am a heart patient and have a mechanical aortic valve replacement. I am currently taking Coumadin to control my Pro Time INR. Please tell me if their is a problem or conflict by using an andrographis product with a Coumadin  product.
   A. We have no research regarding the concurrent use of Coumadin and andrographis or practically any herb, so we don't know.

Q. My doctor wants to put me on Coumadin to prevent blood clots, because I have being having episodes of atrial fibrillation. But I would prefer to go on Wobenzym N, my doctor wants any clinical studies, research results or scientific information or hard evidence on it. Can you please tell me where I would be able to find this information or how I can obtain it.
   A. See the link for Wobenzym.

The cardiologist of a friend is keeping her Coumadin level at 1.2 in the wake of a serious episode of atrial fibrillation as a result of which she underwent an ablation operation a few months ago. It has been recommended that she add krill oil to her regimem for keeping herself in good health now. Is it safe to begin taking krill oil? I have been calling the various companies who produce a form of this fish oil and the answer so far is start with one pill but no information specifically about how much of a thinning effect there is. Can you please tell me a little more about how these substances interact.
   Krill oil has EPA and DHA, fatty acids that do thin the blood. Caution is advised when combining blood thinners with supplements that thin the blood. Your friend's cardiologist is the person who needs to make the final decision regarding the appropriateness of combining Coumadin with fish oil or krill oil supplements.

My 86 year old aunt has been taking 6 mg of Coumadin for about a year to keep her INR in the correct range (2-3). Last month, her eye began to bleed; she has neovascular glaucoma. She is having a laser treatment for this in a few days. The eye surgeon told her she is either going to lose her eye or have a stroke. In other words, without the Coumadin, a stroke, but with the Coumadin, there will be more intraocular bleeding.

Can nattokinase substitute for Coumadin as a blood thinner?
   Nattokinase and Coumadin work in different ways. Coumadin is a drug with serious positive and negative effects, and hence changes in your treatment plan should not be done unless you discuss with your doctor. It is not clear to me how potent nattokinase is compared to the blood thinning drug.

I'm trying to find out if Hibiscus tea will affect the Coumadin that a person is on who has 2 factors for having blood clots they are prothrombin and Lupus anticoagulant.
   I have not seen studies regarding the role of hibiscus herb in interacting with Coumadin.

is it safe to take one of the following if you are taking this prescription blood thinner: Shilajit, Cabergoline [Dostinex], and Passion Power for men.
   Such studies have not been done so it is not easy to predict. Any new additions as far as supplements should be done in low dosages and gradually and one at a time with medical approval.

Is ingesting quercetin contraindicated for Cumodin patients?
   I am not aware of such studies with qurcetin but it is possible it could have mild blood thinning potential.