Is It Safe to Mix Fish Oil and Blood Thinners?

I make no bones about how much I love fish oil. I’ve recommended it for more than 20 years and have seen some great results in people who take it—including improvements in atrial fibrillation, blood pressure, heart rate variability, a racing heart and other arrhythmias. The omega-3 essential fatty acids that fish oil contains help neutralize the effects of Lp(a), reduce arterial inflammation, improve endothelial function, and promote healthier circulation and clotting.

I’ve even been known to say that taking fish oil is “like wrapping the heart in a warm blanket.” Who wouldn’t want that?

But as perfect as fish oil may seem, I’m often asked by people who take prescription blood thinners if it’s safe to combine fish oil with their Plavix or warfarin (Coumadin). They worry that the blood thinning effects of fish oil will interact with their medications and put them at risk for excessive bleeding.

Increased Fish Oil Use Raises Drug Interaction Fears

This is not a new concern, and it was raised again after a study that looked at the use of prescription drugs, OTC drugs, and nutritional supplements appeared in JAMA Internal Medicine.

In 2005–2006, researchers monitored a nationally representative sample of more than 2,000 adults, ages 57–85, to learn how many medications each person, on average, was taking and for what drug interactions the study group was most at risk. (“Medications” were defined as prescription drugs, OTC drugs, and supplements.) In 2010–2011, the researchers repeated the survey with a similar demographic group and compared the findings.

Not surprisingly, they discovered that more people are taking more prescription drugs, with statistically significant increases in the use of statins and antiplatelet blood thinners. They also found an increase in the use of supplements, with a statistically significant uptick in the number of people taking fish oil.

The percentage of people at risk for potential major drug interactions was found to have almost doubled, from 8.4 to 15.1—a jump the research team strongly implied could be due to the increased use of fish oil and blood thinners.

Fish Oil and Blood Thinner Interaction Realities

I don’t disagree that fish oil and blood thinners—particularly antiplatelet blood thinners—need to be handled with care. The omega-3 fatty acids in fish oil help make blood platelets less likely to clot; antiplatelet blood thinners do the same thing. Too much of both can increase the risk for excessive bleeding from minor, everyday cuts or from the gastrointestinal side effects of drugs like aspirin or NSAIDs, as well as bruising or injuries that may occur as the result of a fall. Blood that is too thin also raises the risk of hemorrhagic stroke, especially in patients over age 85.

Still, the study did not provide any evidence that people taking both fish oil and blood thinners are in imminent danger. In fact, there are no studies that I know of to support such a claim.

There are, however, many studies that demonstrate the cardiovascular benefits of fish oil and omega-3 essential fatty acids on blood pressure, arrhythmias, triglycerides, and arterial health.

How to Safely Take Fish Oil and Blood Thinners

So back to our original question: Is it safe to mix fish oil and blood thinning drugs?

I believe it is, as long as the dosages of all drugs (including fish oil) are managed properly.

Modest amounts of fish oil, say 1–2 grams daily, generally can be tolerated even if you are taking prescription blood thinners. However, doing this is not without some risk—so it’s absolutely essential that you be up front with your doctor about the fish oil products you’re taking and how much, to avoid unsafe drug interactions. I cannot emphasize this enough. You must work collaboratively with your physician and regularly monitor the clotting agents in your blood. (Prepare for the conversation by reading how to talk to your doctor about supplements.) It’s also crucial that you don’t replace a blood thinning therapy that your doctor has prescribed with fish oil, unless that doctor says it’s okay.

Remember, too – blood thinners aren’t limited to prescription medications. Aspirin is also an antiplatelet therapy. If your doctor has prescribed an aspirin regimen for you, you also must tell him or her about your fish oil use. Other supplements can have blood thinning effects, too. These include garlic, nattokinase, vitamin E, ginger, and bromelain.

If you find that fish oil causes your blood to thin too much, use it as an opportunity to ask about reducing the dosage of your prescription blood thinner. But don’t give up your fish oil, unless you absolutely have to. The benefits are simply too great to forego.


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  1. Mary

    on September 7, 2016 at 2:30 pm

    Is Krill Oil the same and has the same effects as the fish oil?

  2. Sheri Margulies-Semel

    on September 7, 2016 at 3:28 pm

    I have been taking fish oil (YOUR Omega 3 caps) for years now. I no longer need Coumadin for my afib because that seems to have been ‘cured’ by my third ablation 6 years ago…knock on anything that even RESEMBLES wood! However, I do have very, very serious back problems and won’t take prescription meds like Vioxx or whatever is out there now. I was taking Natto (your Natto) for a very long time, but I found that substituting one Excedrin a day for one of the two 650 mg. acetaminophen tabs I was taking along with 100 mgs. of Tramadol a day, is more effective than the two acetaminophens. I also take lots of your Pro Med formula, but of course, I’m still in pain and just try to live with it. I see my chiropractor every 2weeks, stretch and do Qi Gong daily, and at 70, that’s all I feel I can do. My question regards the aspirin in the Excedrin. Aside from seeming to cause me some gastric distress (when it happens I lay off the pills for a few days), do you see any reason to worry about the combination of the Fish Oil with the Excedrin? I don’t take the Natto now for this reason although I think it was a healthy thing to take.

  3. Elizabeth

    on September 8, 2016 at 5:01 pm

    How do you feel about coconut oil for frying eggs, etc?

  4. Albert Padgett

    on September 8, 2016 at 5:02 pm

    I have been taking your Omega Q Plus for years have been very pleased with results.
    I am on warfarin taking 7& one half mg a day, would like to add your curcuwin turmeric extract(rhizome) , can this be added
    without any adverse effects, I have a-fib as well.

  5. HeartMD Editor

    on September 8, 2016 at 5:24 pm

    Hi Elizabeth, Dr. Sinatra likes it; like butter, coconut oil has a higher smoke point than vegetable oils, which means it’s less prone to oxidation, and thus a healthier choice to fry with.

  6. Ross Bayne

    on September 9, 2016 at 2:08 am

    Hi Sheri – This is a purely anecdotal and personal comment, and I offer it only as such, and I know nothing of the detail of your back condition [although from what you say, you are managing with some duress, and I have every sympathy]. Having said that, there are a number of anti-inflammatory agents around with lesser side effects that you may like to consider, I am sure under advice. Albert P [above] mentions Turmeric [Curcumin] which I have been taking recently, and find effective: I also use a gel and capsules based on an unlikely sounding substance that is the basis of Pernaton [trade mark] – this is a New Zealand green lipped mussel extract, processed in Switzerland, that has [I have found] a wide variety of uses, and best priced with Amazon – the primary caveat is being wary if you have a fish/ marine allergy/ intolerance/ sensitivity. I have found it excellent for anything from headaches to the lower back aches I still encounter from Pilates and Yoga, and also I would add the huge benefits over time! Lastly, as a counter to the gastric irritation you occasionally encounter, I would proffer a local antagonist, Gaviscon, either in tablet or liquid form, that instantly provides relief.
    How have I encountered these, and what is my position? Well, I am an ICU health care professional in UK, recently retired, but with a long term interest in alternate approaches – 4-5 years ago, an orthopaedic surgeon I consulted stated that I required an urgent total knee replacement, based on my X-ray, and subsequent MRI/ CT scans. I was finding difficulty walking, in a lot of pain and concerned about my prospects! We discussed it, and decided that we would be conservative in action, look to other approaches, which I have done [Steven Sinatra and Jim Healthy’s book on arthritis has been a stalwart text for me] … I will only say – in brief – that matters have hugely improved, and no operation.
    Be encouraged – my approaches are very critically aware based but take from many sources, always seek ways that work with the body’s own mechanisms and minimise side effects. I am active, walk, SCUBA dive, play with the grandchildren, and I am healthy – and take a range of supplements – I wish you well – Ross

  7. joannehyrkin

    on September 9, 2016 at 2:31 pm

    i just read your article i must say i follow youe letters all the time and also follow your advice i have afib iwas taking xyltol aand after reading your article on blood thinners i switched to eliquis i take it 2 times a day 5m each time also on beta blocker nalodol one a dayi also take epa.dha 500 ec oils 2 a day also multi vit 400 iu vit e.also it has b12450mcg and thsaes are included in the multi i take 6 a day aalso i eat pineapple which has bromelein are these things i need to be concerned about i will also ask my heart dr but you know much more thank you.

  8. HeartMD Editor

    on September 9, 2016 at 2:59 pm

    Hi Albert – Dr. Sinatra has had patients in the past who took both tumeric and warfarin, and does not generally have concerns about taking both, but cautions against high doses (over 1 gram of day), as it could cause an interaction. Always monitor use of both with your prescribing physician.

  9. HeartMD Editor

    on September 9, 2016 at 3:08 pm

    Hi Sheri, If you’re having abdominal discomfort with aspirin usage; Dr. Sinatra suggests trying grounding to help alleviate your pain and lessen any dependency on aspirin. See
    Like aspirin & fish oil, grounding also has blood thinning effects, so he advises always keeping your doctor informed about any blood thinning agents you’re using.

  10. carolyn Farrell

    on September 9, 2016 at 7:42 pm

    My husband takes Pradaxa 150 mg. 2 times a day. He also takes 81 mg aspirin a day. He has been taking 4 of Dr. Sinatra’s COQ10 plus for many years . He is 80 years young and has had a heart attack, open heart surgery and a Stent. He has a difibrilator pacemaker combo. He has benn cared for by two cardiologist, and they are both aware of all the fish oil, flax seed oil and other supplements that he takes . The only problem with thinning blood is bruising when he bumps himself. Because he takes Pradaxa, there is no need for regular protimes like you have to have with coumadin. HIs physcians do not seem to think that there is any harm with the combination of the two in making his blood too thin.The only precaution is if he is going to have any procedures , in which case he is instructed to be off of all of the items that thin the blood for at least three days before the procedure.

  11. joannehyrkin

    on September 10, 2016 at 4:58 pm

    i am 83 years old and have afib i am on eliquis based on your articleand i take nalodola beta blocker i do take fish oils 2 a day and a multi whuch has vitamin e and b12 i also eat a bunch of pineapple my heart dsr has not given me any tests to see how my bklood is i will say something to her but should i continue to take these things i do not have hifgh blood pressure or problems of cholesterol i do not even know i am in afib thank you i reads your newsletter faithfully. joannehyrkin

  12. Rajen

    on September 15, 2016 at 6:18 am

    Am 67 and I do take fish oil for quite some time. I was prescribed clopidogrel and 50 gm metoprolol because of interlock arteries After 3 years when I was getting chess pain the private cardiologist added 30mg. Diltiazem and I was o.k.But now the hospital cardiologist says that if I take metoprolol with diltiazem it will block my heart.I am in a dillema .. Please advise me doctor.Thanking you in anticipation.

  13. HeartMD Editor

    on September 15, 2016 at 9:44 am

    Hi Rajen, Dr. Sinatra gives as much heart-health information as he can to the general public through this site, but cannot give individual medical advice to non-patients (and he no longer sees new patients). This is something you need to discuss with your doctor or another doctor who can give you a second opinion. We’ll try to get more information up at HeartMD about the medications you mentioned, though. Best wishes.

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