Q. Is it true that you should not drink cranberry juice if you are on Coumadin to thin the blood?

A. Several years ago British regulatory authorities issued a warning to patients taking warfarin (Coumadin) not to drink cranberry juice. This combination was associated with excessive bleeding and one man died. An article in the British Medical Journal (BMJ) suggested that patients taking warfarin would be prudent to limit their cranberry juice consumption.

Since that initial publication, there have been other reports of interactions and contradictions. This interaction remains somewhat controversial. One study showed that two cups of cranberry juice a day did not lead to bleeding worries. But there is a case of a man who died after drinking a substantial amount of cranberry juice daily after two weeks. The cause was internal hemorrhage linked to an interaction with his blood thinner warfarin.

The most recent reference is another case report in which a person twice experienced elevated INR (a measure of blood thinning) after drinking cranberry juice cocktail.

Our standard reference for drug interactions, Drug Interaction Facts, recommends that people should avoid drinking large amounts of cranberry juice if they are on warfarin.

You can access our free Guide to Coumadin (Warfarin) Interactions here.

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  1. Cristina N

    cln May 30, 2017

    So I’m happy to be alive and take my warfin faithful everyday. 12 years ago I got a mechanical heart valve and will be on blood thinners till the day I go home to be with JESUS.

    I started feeling like I was getting a bladder infection and didn’t want to be on antibiotics so I took a couple of cranberry capsules at night then checked my INR (I have a home machine) and it was elevated – not dangerous but higher then a few days before. Cranberry definitly reacts with blood thinners!

  2. Astra

    I agree, I’ve been told by my doctor that all supplements are fine, and I am now going through the steps to figure out the culprit for a period that hasn’t stopped in a month in spite of a hormonal IUD that’s been working just fine before to keep things in check (I’m on long term oral anticoagulant). Rosehip oil for my face – ditched, bleeding continued; another week into it, it occurred to me to check if there’s info on cranberry juice (also doctor-recommended, been drinking up to 8 oz/day for a couple of weeks). Sounds like “pick a poison” to me…

  3. Malli

    Iam not on any blood thinners but I am on blood pressure tablets.i also suffer heavy bleeding during my periods and have since discovered that whenever I don’t drink cranberry juice my bleeding is normal but whenever I drink it I have very heavy periods.so I will not drink cranberry juice anymore.

  4. Myra

    I am on Coumadin and I had an episode where I was snacking on Craisins dried cranberries and I stated to have fainted on my left side, when I went to the hospital I found out my left kidney was bleeding. so I was told not to eat cranberries amy more.I didn’t stop completely I just eat very little.

  5. Maria A.


    My Mom takes Coumadin 1mg tablets and she takes 1 then 2 then 2 and then 1 throughout the week (she has to alternate to keep a regular INR). She recently had blood work done and her thyroid and kidney level was up, they are saying this is most likely due to the amiodarone she is on.

    We are a bit concerned and I am wondering, if it would be ok for her to start taking a lower dose of cranberry. Do you think it would hurt her to do so? I am just looking for an honest opinion because it seems that it is quite difficult these days to get that from a Dr. and/or people that are selling products because it truly seems all they care about is selling their product and making money.

    Any suggestions would be greatly appreciated.

    • The People's Pharmacy

      We think that adding cranberry tablets to her Coumadin could be too risky, and we are not sure whether it would offer her protection.
      Amiodarone can indeed affect thyroid, kidney and other organs.

  6. txnicegal

    The interaction happens no matter when you drink the cranberry juice it still interacts with the warfarin. Not drinking juice while taking medication.

  7. MAL

    I was diagnosed with Antiphospholipid syndrome in 1999, and frequently have DVTs in my lower extremities. I have been taking coumadin (warfarin) ever since. PT/INR blood levels are drawn weekly, and my INR consistently runs between 1.5-2 on a steady dose of 12mg daily. I am susceptible to repetitive UTIs. Whenever UTI symptoms begin to manifest I drink large amounts of cranberry juice, and when I do my INR increases to 6.7 – 11.2.
    Despite the lack of official research findings to substantiate interactions between cranberries/cranberry juice and coumadin (warfarin), and its effect on plasma levels of the drug, I am thoroughly convinced that there is indeed an interaction. The high level of antioxidants called flavonoids contained in cranberry juice may inhibit the function of the enzymes that break down warfarin in the body, causing the drug to remain longer than usual. This theory would support the fact that the only time my INR levels reach dangerous levels is when I drink cranberry or cran-grape juice.
    Therefore, I would encourage patients taking coumadin (warfarin) to carefully weigh the potential risks of anticoagulation therapy against its potential benefits.

  8. MJR

    I have been taking warfarin for a long time and am just now finding out that cranberry juice can control the effects of the drug. I have taken a lot of prednisone during this time and was blaming it for all of the high readings. Now, come to think of it I do believe cranberry juice may have been the problem. I will tell my coumadin nurse and see what she has to say about the problem. Maybe we can get the darn stuff regulated. I did have all of the warfarin side affects.

  9. R. MacDonald

    My INR bounces between 3 and 1.8 for no apparent reason. I’ve taken other people’s word for it about spinach and broccoli. I’m reasonably sure I shouldn’t eat cabbage, but other than that, nothing I eat seems to have much correlation with any change in INR. I had been avoiding cranberry juice. Since the evidence of likely harm doesn’t look all that convincing, I think I’ll stop worrying about that and see what happens.

    • Bws

      My wife is on coumadin and had that problem it first read 3.5 and the dr called and said stop coumadin for 5 days and come back in for a test… we did and the next test was almost the same 3.2. Come to find out it was the way she was working… hot days, lots of water. We regulated amount and times she drank the water and in a week it dropped to 1.8. Since she was 78 and suffering from dementia, we slowed the pace she was working as well as regulated her drinking. Since all that, we have been taking 1 gm of Turmeric and 1 gram of resveratrol each day and she has had more consistent readings altho on the lower side in the 1,8 to 2.6 scale. The Turmeric seems to be the regulating agent.

  10. Chastity W.

    I have Multiple Bilateral Pulmonary embolisms….and I would like to share the episode I had when I drank just a 12 oz serving of cranberry grape juice. It was horrid and sent my INR level to a 16.4…the previous day check was only like 6.5, not theraputic, but not a deadly 16 either.
    I am on Coumadin (warfarin) as most of you are. PLEASE speak to your physician before venturing on any new endeavor regardless of how “successfull” you’ve heard it to be for others. We all are different, hence, some are adversly affected while others are not.
    The best advice is not to give advice about what is good for you and suggest it to another. Safety please…this is nothing we should toy with.
    Speedy recoveries to us all!!

  11. BTO L

    Really – the Cranberry Concentrate Pills changed my life. I would get extremely painful UTIs at least once every couple of months. That meant doctor’s visits and urine cultures, and antibiotics. Nobody wants to take that many antibiotics!!
    I tried Cranberry pills rather than go on prophylaxis and they work! I don’t know how, but they do. I take one in the morning and one in the afternoon and stay as hydrated as possible, and I have been UTI free! Definitely worth the money.

    • Maria A.

      You didn’t mention if you were on Coumadin taking the pills though?

  12. J. O.

    I am glad to see the new posts coming in about cranberry juice and blood thinners. In my initial post I should have made it clear that my primary care doctor was (is) aware that I drink cranberry juice regularly, and she has gone over the caveats with me. I never drink any kind of juice when taking my medications and follow the doctor’s instructions as to with/without food as well.
    I have never been on any blood thinner other than coumadin. For anyone who takes the cranberry supplements or drinks it while using other kinds of blood thinners I would strongly suggest you have a discussion about it with your doctor. I was only speaking in regards to my own experiences.

  13. RES

    In the case of Coumadin….my husband had a
    Serious internal bleeding because he was on
    He was taking Coumadin–Aspirin–& Plavix.
    He was hospitalized with serious internal
    Bleeding. People MUST be aware of excess
    Blood thinners.

    • Shari
      Parkersburg, WV

      Why in the world would ever have him take all of those blood thinners at the same time? That is definitely a malpractice situation and should be reported to the American Medical Association.

  14. CBL

    Does this include cranberry pills? I’ve been taking these for years to avoid bladder infections.

  15. J.O.

    I have been on coumadin (warfarin) for 21 years now due to Factor 5 Leiden and will remain on it for the duration of my life. I don’t drink sodas and find other fruit juices too sweet but drink at least one 8-ounce glass of cranberry juice cocktail each day. My INR is fairly stable (it reacts more to the leafy green vegetables) and have not had any problems with my protimes or INR numbers being excessively high. I think the key is moderation.
    People’s Pharmacy response: Moderation is the first key, and the second is consistency. You have embraced both.

  16. MLB

    What about other blood thinners, like Plavix and Effient?
    People’s Pharmacy response: They aren’t expected to interact with cranberry juice.

  17. cpmt

    I think that anyone should not take medication with any kind of juice, only with water and wait a couple hours after taking medication to drink any juice, milk or sodas & also herbs/supplements/spices etc…Dr.’s still don’t know many things about medications side effects/reactions/interactions etc…

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