bowl of turmeric spice

Who would imagine that curry, guacamole, cranberries or mango could interact with a medicine to cause a potentially life-threatening interaction? All these foods may alter the action of warfarin (Coumadin), an anticoagulant used to prevent blood clots. What should you know about food-drug interactions? Did you realize that turmeric interacts with warfarin?

Scary Food-Drug Interactions:

Both doctors and patients may overlook food-drug interactions when they are discussing a new prescription medication. As a result, patients may not realize when their eating habits put them in harm’s way. One reader learned about this the hard way.

Turmeric Interacts with Warfarin:

Q. Turmeric increases the anticoagulant effect of Coumadin. I have been on Coumadin for 15 years because of an artificial aortic valve.

I had read that turmeric was effective in lowering cholesterol and began sprinkling it on broccoli. My INR went up dramatically and my pharmacist said, “STOP!” Have there been any studies on the blood-thinning effect of turmeric?

A. You are not the first person to report this interaction between Coumadin (warfarin) and turmeric. Others have reported a spike in their INR lab values (a measure of blood anticoagulation) and we believe this is a dangerous combination. Our fear is that this could lead to a serious bleeding episode.

Interactions That Reduce the Effectiveness of Warfarin:

Coumadin is actually an exception. Most prescribers are aware of potential interactions between this blood-thinner and the vitamin K contained in green leafy vegetables. Excess vitamin K can reverse the effect of warfarin and lead to dangerous blood clots.

In response to this advice, however, people may restrict their diets too stringently. Some patients become frustrated wondering how to get their vitamins because they have been told to swear off all salads, vegetables and multi-vitamins containing vitamin K. Instead, health care professionals should tell them to get the same amount of vitamin K each day from food (as they would from a multivitamin). As a result, the prescriber could adjust the dose appropriately.

Very few people taking warfarin are warned that avocados, green tea or menthol cough drops could also interfere with warfarin’s effectiveness. Dietary supplements may pose a risk as well. St. John’s wort, Coenzyme Q10 and ginseng may interact in the same way.

Interactions That Increase Warfarin Activity:

Cranberry juice, mango, garlic, fish oil and turmeric (in curry or in curcumin pills), on the other hand, may increase the blood thinning activity of warfarin (Norwood et al, Journal of Pharmacy Practice, Dec. 2015). A recent review cites evidence that curcumin has anti-clotting activity (Keihanian et al, Journal of Cellular Physiology, June 2018). Scientists did research in rats to check out interactions between curcumin with warfarin and clopidogrel (Liu et al, Planta Medica, July 2013). They found that curcumin affects absorption of both warfarin and Plavix, but they saw no evidence of increased bleeding. The higher INR values that many patients have reported to us suggest that this combination is too tricky to try at home, however.

Other Food and Drug Interactions:

Many other drugs and dietary supplements can be affected by food or drink. Tea (hot or iced) can reduce the absorption of iron from pills or non-meat foods such as spinach. Coffee and foods based on soybeans cut absorption of the thyroid hormone levothyroxine (Skelin et al, Clinical Therapeutics, Feb. 2017).

Fiber in bran can diminish the absorption of a powerful heart medicine called Lanoxin (digoxin) and statin-type cholesterol-lowering medicines such as Lipitor (atorvastatin) and Zocor (simvastatin). High fiber foods such as bran muffins can also make certain antidepressants less effective.

Watch Out for Peppermint:

Peppermint is a popular ingredient in candy, chewing gum, cough drops and herbal tea. It is used in dietary supplements for treating irritable bowel syndrome. Research shows that peppermint may affect enzymes in the body that that help process many medicines (Unger & Frank, Rapid Communications in Mass Spectrometry, 2004). Unfortunately, the practical implications of this activity have not been explored.

Food-Drug Interactions with Grapefruit:

Grapefruit has a similar but stronger impact. It can raise blood levels of a range of medications including Lipitor, Mevacor and Zocor as well as BuSpar, Estrace, Plendil, Sonata, Tegretol and Viagra. Significantly, a recent review found that grapefruit juice increased blood levels and duration of the opioid oxycodone (Feng, Zhu & Zhou, Journal of Pain Research, May 24, 2017). The volunteers in the study drank almost a cup of grapefruit juice three times a day.

Certain drugs used to treat overactive bladder, such as fesoteradine (Toviaz), also interact with grapefruit and grapefruit juice (Pasko et al, International Journal of Clinical Pharmacy, Dec. 2016). As a result, people may be more likely to suffer side effects such as dry mouth, irregular heartbeat, blurred vision, headache, difficult urination or constipation.

The allergy drug fexofenadine (Allegra) interacts with grapefruit juice as well, albeit through a different mechanism (Yu et al, Journal of Pharmaceutical Sciences, online April 13, 2017). Paradoxically, this interaction dramatically decreases the amount of fexofenadine in the bloodstream.

Learn More:

Such food-drug interactions can be confusing. Anyone who would like to know more may want to consult our Guides to Coumadin, Food and Grapefruit Interactions.

Drugs can interact with other medicines as well as with foods, beverages or dietary supplements. Bad combinations cause thousands of deaths each year. The best protection is information and vigilance. Your health professional may not be aware of every possible danger, so you need to protect yourself.

Revised 5/28/18

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  1. Gary

    As I have served in mission work in Bangladesh I developed a taste for eastern food high in turmeric, curry, ginger root, and garlic. For years I have eaten at least three servings of eastern foods per week. I am now 81.

    When I was 79, I was prescribed coumadin for a-fib, and about four weeks after I started taking coumadin I started to have infections and was hospitalized four days for a very serious infection. After I was released from the hospital the infections continued. Although I was not hospitalized for the subsequent infections, my primary care physician was running out of anti-biotics to treat the concurrent infections. When I stopped taking coumadin, the infections stopped.

    I suspect that I did not need the coumadin any longer, as I was eating a diet high in turmeric, ginger root, curry, and garlic. I have a cardiologist who is very aware of this. I am still alive and doing very well without any blood thinners.

  2. Diana
    Boone, NC

    Drinking grapefruit juice or eating grapefruit and taking a calcium channel blocker can cause a deadly interaction with heart rhythm.

  3. Robert G.

    I’ve been on Warfarin for years, and my INR is consistently in range. I love fruits and vegetables and eat plenty. The secret is being consistent in what one eats. If you have a consistent diet, your dosage can be adjusted to match it, and you’ll be fine.

  4. Ms Christine D.

    Would using Tumeric along with another type of blood thinner cause similar problems? I am currently taking Apixaban (Eliquis) for AFib.

  5. DAVE T

    Over the Memorial Day weekend I read the People’s Pharmacy article about raw onion and bee stings. Sunday afternoon I was working in may yard and got stung by a wasp on my cheek. After checking to make sure the stinger was out, I remembered the article that day. Cut a small piece of onion and applied it to the place where I was stung. The stinging pain was gone in 5 minutes. THIS WORKS!!! I still had some swelling and discomfort but the pain was GONE!

  6. Theresa
    Sand Lake, NY

    I also am on Coumadin and just wondering if I could or should take turmeric and what changes I should take or make to taking this for arthritis?

  7. JAMES

    I have none.

  8. JAMES

    Have any of you balanced Warfarin with turmeric successfully????

  9. D .Kingstone

    Has anyone successfully taken tumeric tablets and been able to decrease the warfarin amount they are on … Because of the side effects and getting arthritis that is starting to bother him .my husband is looking at maybe trying this .. Tumeric he has taken in the past has helped his arthritic problems a lot , we have our own INR machine so would be able to check his levels regulary and keep track of where his blood is at .. Any imput would be appreciated …

    • Steven

      I took Turmeric/Curcumin along with Warfarin for 6 years with no side effects. Warfarin requires monthly blood tests, whereas Xarelto does not, so I switched to Xarelto 2 years ago, and still no side effects.

  10. Helen
    British Columbia

    I have been taking warfarin for a minimum of 40 years, now very arthritic hands leads me down a new path, would appreciate any comments re taking turmeric , cinnamon and fresh ginger about 1/2 teaspoonful of each daily in a large cup of warmed Almond Milk

    • Gerri F.

      My nurse practitioner told me to continue taking turmeric (for arthritis) and eating small amounts of green leafy vegetables which are needed to prevent calcification. She said she can balance that with the dosage of warfarin prescribed. So far it has worked out. My INR reading is just where she wants it to be. I take 5mg warfarin every night, and my INR is 2.0. I take tumeric about twice a week, only 1/2 capsule, and I have no arthritic pain.

  11. Cynthia

    My sister’s experience with Turmeric and Coumadin. My sister’s INR readings were at a steady 9 ml a day for a long time. A friend of ours introduced us to the natural herb Turmeric to help with her diabetes, which it did begin to lower. We started taking the Turmeric powder about a week before her next IRN lab. We received an alarming call from the lab at 6:15 am the next morning to please stop all Coumadin until we heard from her Dr. later that morning. I know we had not changed our routine with diet or exercise, when I remembered the one thing we had changed was adding a forth teaspoon of Turmeric with our morning’s meal.

    This is not to take away from the benefits of Turmeric, but because of the lab result, perhaps Turmeric and Coumadin should not be taken together. That’s all.

  12. RobB

    I am 61 years of age & have been taking 3-4 mgs daily of Warfarin for nearly 20 years. I have AF Atrial Fibrillation & have recently been diagnosed with AS Ankylosing Spondylitis – an autoimmune arthritus.
    I know the Warfarin keeps my INR around 2.1 to 2.4 regularly & improves my chances of not having a stroke but it gives me no joint relief.
    I am seriously considering taking Turmeric (Curcumin BP )in conjunction with the Warfarin. The Curcumin comes in 1100 mg tablets.
    I planned to take 1 Curcumin morning & night & 2 mg Warfarin once at night.
    I also plan to have regular INR tests.
    Has anyone out there tried this approach?
    All input appreciated.

  13. marvin
    Newton MA.

    I have been taking Curcumin Complex for 4 years years as a result of reading that studies at M.D. Anderson may possibly have an effect in treating M.G.U.S. I advised my oncologist at Dana Farber and have noted that during the past 10 years there have been no appreciable increase in paraproteins.

    Since the Mgus remains stable, tested twice per year and have not noticed any problem with excessive bleeding even with dental treatment, I plan to continue taking 875mg twice daily. I also take an 81 mg. aspirin daily. I hope my decision is prudent.

    • Bonnie

      Hi, I am looking into taking Magnesium-Curcumin supplement, but am on Warfarin 2.5 mg, 4 times a week and 5 mg. 3 times a week. From what I’ve read, I shouldn’t take them both together as my blood would really thin out. I take it because I have permanent A Fib, small leaky heart valve and mild congestive heart failure.

      I would really like to get off of all my meds and go back to all supplements. Could you tell me, do you have A Fib also. If you do, did Doctor say it was okay to take the mag-cur. supplement? Thank you so much for your time. Bonnie

  14. Carolyn

    I have just started taking Curcumin BCM95….are there any side effects if I also take 1 (81mg) baby aspirin a day?

    • Moto

      Right on brother and all the power to you (Y) Oh, and also > thank you!

  15. Elizabeth

    I have been on Coumadin for perhaps 7-8 years for arrhythmia, 2.5 Mg. daily, with periodic INR tests which have been good. My doctor knows I take fish oil. Wish I could get some info if blueberries affect INR levels, also any other dark fruit such as grapes, fruit juices containing dark berries. Had serious bleed 5 years ago requiring blood transfusions so I am careful but not phobic about would-be blood thinners. Does anyone know about these “green drinks” and if they are safe for someone on Coumadin.
    People’s Pharmacy response: If the green drinks have enough kale, spinach or other greens in them to be helpful, they could pose an interaction hazard with Coumadin.

    • Brenda

      I’ve been on warfarin almost 2 years after a PE. I eat blueberries almost daily, large salads and many fresh veggies. My husband makes me green smoothies for lunch at least twice weekly. The secret is to carefully calculate your “greens” and maintain them daily. I eat pretty close to 350 mcg of Vitamin K daily; not terribly different than before the clots. I have however given up kale, collards, chard – just too high in K to make a big mistake. I admit I miss them but that was not a level of risk that I could accept. I eat lots of broccoli and brussel sprouts though. I just keep a running total of how much K is in eat thing. It’s only hard the first week when you’re learning the value and amount of each food item — but well worth it.

  16. norm

    Could using turmeric lead to taking smaller doses of Coumadin ? I know its a balancing act.
    People’s Pharmacy response: doing the experiment would require very close monitoring!

  17. jill850

    In response to the person who mentioned not having seen any Plavix-turmeric connection, I did — big surprise, as I hadn’t yet visited this page. I began bleeding at the slightest scratch, took me a while to figure out what was going on, as I often didn’t even feel it. I was taking high-grade capsules — I wish I could take turmeric instead of Plavix, as I can’t use NSAIDs and have arthritis. Hope this provides a clue to someone else . . .

    • 212mike

      When taking Coumadin, it is extremely important that the patient not make radical changes to diet. A simple change can create a different INR result, so making several changes at the same time may make it impossible to find which new food or supplement is causing a change in the INR. Additionally, since so many substances affect Coumadin, either increasing or decreasing INR measurements, it is important to make changes gradually or one-of-a-time, so that the individual can confer with his medical provider about any changes that result. If a person makes dietary changes slowly and one at a time, Coumadin levels can be adjusted to stay in proper range.

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