Does fish oil cause blood thinning?

Omega-3 fatty acids from fish oil have the capacity to "thin the blood." In reality, omega-3s exert a mild platelet-blocking effect (platelet activation and "clumping" are part of clot formation), while also inhibiting arachidonic acid formation and thromboxane.

But can fish oil cause excessive bleeding?

This question comes up frequently in the office, particularly when my colleagues see the doses of fish oil we use for cardiovascular protection. "Why so much fish oil? That's too much blood thinning!"

The most recent addition to the conversation comes from a Philadelphia experience reported in the American Journal of Cardiology:

Comparison of bleeding complications with omega-3 fatty acids + aspirin + clopidogrel--versus--aspirin + clopidogrel in patients with cardiovascular disease.(Watson et al; Am J Cardiol 2009 Oct 15;104(8):1052-4).

All 364 subjects in the study took aspirin and Plavix (a platelet-inhibiting drug), mostly for coronary disease. Mean dose aspirin = 161 mg/day; mean dose Plavix = 75 mg/day. 182 of the subjects were also taking fish oil, mean dose 3000 mg with unspecified omega-3 content.

During nearly 3 years of observation, there was no excess of bleeding events in the group taking fish oil. (In fact, the group not taking fish oil had more bleeding events, though the difference fell short of achieving statistical significance.) Thus, 3000 mg per day of fish oil appeared to exert no observable increase in risk for bleeding. This is consistent with several other studies, including that including Coumadin (warfarin), with no increased bleeding risk when fish oil is added.

Rather than causing blood thinning, I prefer to think that omega-3 fatty acids from fish oil restore protection from abnormal clotting. Taking omega-3 fatty acids from fish oil simply restores a normal level of omega-3 fatty acids in the blood sufficient to strike a healthy balance between blood "thinning" and healthy blood clotting.

Comments (20) -

  • Marc

    10/26/2009 9:46:32 PM |

    Long time reader, first comment.
    Thank you for so freely sharing all the information.

    Marc

  • Daniel

    10/26/2009 11:02:46 PM |

    Thank you for this!  I have had this question for a long time given the number of things I take that "thin the blood."

  • Kevin

    10/26/2009 11:44:45 PM |

    As a veterinarian I've dispensed fish oil capsules for several years.  Some owners give so many that the dogs smell 'fishy' when seen for routine care.  The owner doesn't smell it since they're with the dog a lot.  The coats are gorgeous, something that doesn't often happen in Wyoming at 7000ft altitude.

  • Dr. William Davis

    10/26/2009 11:47:45 PM |

    Hi, Kevin--

    My two Boston terriers jump for their fish oil capsules, two every day!

    I'm glad to hear from a veterinarian that the coat sheen is indeed from the fish oil.

  • Rich

    10/27/2009 1:27:09 AM |

    Due to an afib episode a couple of years ago, I was taking 20 mg of warfarin per day, plus around 5000 mg of EPA+DHA, and never had bleeding issues.  

    My INR was always a stable 2.0.

    As I've not had an afib reoccurrence, I've replaced the 20mg coumadin with 325mg aspirin daily, and still take around 5000 mg EPA+DHA.  No bleeding issues with that combo either.

  • Catherine

    10/27/2009 3:55:32 AM |

    Glad this topic came up.
    Over the last 5 years, I've had to periodically eliminate my fish oil intake as I would start to bruise badly. My internist said she has seen this occasionally with fish oil and called it "capillary fragility." I bruise easily anyway, but it would really get bad with fish oil. So there must be some quality in fish oil that influences this.

    Then about 6 months ago I started a strong supplement change to help with my low bone density--already taking magnesium and calcium but added:
    Boron, K2, silica,pomegrantate juice, and BIG increase in vitamin D.
    I also increased omegas to 3,000 a day which I was not able to tolerate before.

    It has been over 4 months since I have had ANY bruise---which is just unheard of for me. I usually have 3-4 different bruises on arms/legs. So something in these supplements  strengthened my capillaries I guess, and I can now take high fish oil doses!
    Anyone else had a bruising problem with fish oil?

  • Dr. William Davis

    10/27/2009 11:04:59 AM |

    Hi, Catherine--

    Fascinating observation!

    I'll bet it has something to do with the vitamin D, more than anything else. Vitamin D seems to strengthen structural tissues in bones, muscle, heart valves, and perhaps capillaries and other small blood vessels.

  • trix

    10/27/2009 11:59:37 AM |

    Several years ago I bruised easily for a while and attributed it to taking garlic supplements daily.  I started taking Vit C and the bruising stopped.  I don't think it had to do with fish oil (in my case); I don't think I was taking fish oil at the time.

  • Daniel

    10/27/2009 9:37:33 PM |

    I too achieve rapid blood thinning when taking 2400mg of EPA/DHA per day. That's only 4 pharmaceutical grade capsules. Even after my vitamin d levels were normalized I still got bruising.

    I now take Vitamin K2 (MK-7 natto extract) twice a week and it's allowed me to bump my EPA/DHA up to 3600mg with no ill effects or bruising.

    It was either supplement or eat a lot of aged cheese, they both seemed to do the trick in my particular case.

  • Healthy Oil Guy

    10/27/2009 9:53:51 PM |

    Thank you for sharing this study with us.  It helps clarify whether there is a risk for blood thinning from taking fish oils.  This information may help individuals who are taking blood thinning medications and considering adding fish oils to their daily diet.

  • Dave

    10/28/2009 2:22:01 AM |

    Catherine,

    Without a doubt, your cessation of bruising was due to vitamin k2. I routinely take nattokinase, large doses of fish oil, curcumin, and other blood thinning agents, and if I don't take vitamin K2, I will begin bruising. (I also take high doses of Vitamin D). When I take K2, I have absolutely no bruising.

    Vitamin K2 has many clinical trials showing that it helps endothelium  integrity and elasticity.

    Also, grapeseed extract and pine bark extract (specifically oligomeric proanthcyanins) has the same beneficial effect.

  • Catherine

    10/28/2009 4:41:41 PM |

    Daniel,

    That's really interesting! There is a lot of research on K2's effect on strengthening weak bones. Bone fractures go down considerably when high doses of K2 are used (Japan is using K2 as osteoporosis treatment) BUT studies show it needs to be in conjunction with adequate calcium and Vitamin D---they work synergistically for bone strength.  So it makes sense that K2 and D could do the same with strengthening fragile capillaries. I am also taking the M7 natto form.

  • Catherine

    10/29/2009 12:01:36 AM |

    Dave,

    Thanks for sharing your experience with this, you've really confirmed it now for me.  I can't believe I have suffered with this for most of my life with no answers (tried high dose Vit C, grape seed, etc) and now within months on K2, there's no bruising and I can tolerate fish oil. Hope my bones are responding this well!
    This blog is so helpful....

  • Mina

    10/29/2009 12:21:31 PM |

    Thanks for posting this. The question recently came up in our office. I like your assertion that omega-3s restore the blood to normal and remove abnormal clotting. And to comment on a post above, our dog has a beautifully shiny coat and takes 2 pure EPA capsules each day!

  • Term papers

    1/26/2010 3:40:08 PM |

    I have enjoyed reading That During nearly 3 years of observation, there was no excess of bleeding events in the group taking fish oil. (In fact, the group not taking fish oil had more bleeding events, though the difference fell short of achieving statistical significance.

  • Viagra Online

    8/23/2010 6:41:39 PM |

    I've been drinking fish oil for many year and I don't have any chance in my body people use to said me that but I think it is just a rumor.

  • buy jeans

    11/3/2010 10:19:55 PM |

    I'm also especially gratified that a woman now holds our record. I'm uncertain why, but the ladies have been shy and the men remain the dominant and vocal participants in our program. Speak up, ladies!

  • moseley2010

    12/7/2010 2:37:16 AM |

    I haven't heard of this problem
    fish oil supplements. But now we know what to tell them when this sort of concern comes up. Fish oil or Omega-3 is really beneficial to health. It's just important that it comes from clean waters.

  • Jack

    3/12/2013 7:03:38 PM |

    What is an appropriate dose of fish oil for someone taking coumadin?

  • dorange

    6/15/2014 3:53:03 PM |

    Dr. Davis, when  person is taking Tamoxifen...
    (1) is it safe to take vitamin k2 or K1?
    (2) will fish oil have a role in preventing blood clots?

Loading
Fish oil for $780 per bottle

Fish oil for $780 per bottle

At prevailing pharmacy prices, one capsule of prescription Lovaza fish oil costs $4.33 each.

Yes, you heard right: $4.33 per capsule.

What do you get for $4.33 per capsule? By omega-3 fatty acid content, you get 842 mg EPA + DHA per capsule.

I can also go to Sam's Club and buy a bottle of their Triple-Strength fish oil with 900 mg omega-3 fatty acids per capsule at $18.99 per bottle of 180 capsules. That comes to 10.5 cents per capsule. That puts the price of fish oil from Sam's Club at 97.6% less cost compared to Lovaza for an equivalent quantity of omega-3 fatty acids.

What if we repriced Sam's Club's Triple-Strength and brought it "in line" with what we pay for Lovaza? That would put the value of one bottle of Sam's Club Triple-Strength fish oil at $780 per bottle.

I take patients off Lovaza every chance I get.

Comments (16) -

  • Cathy

    8/19/2009 10:31:05 PM |

    Thanks for that.  I still take Lovaza; have been lazy about switching.  I just checked the price my mail-order pharmacy pays and it's $546 per bottle of 120, or just over $1.50 per capsule.  While considerably less than what you quoted, it's still $6 per day and $2185 per year!  I'd no idea.  Plus I take Niaspan for another $900 per year.  I'm switching to OTC for both.  No wonder insurance rates are going up!

  • John Smith

    8/19/2009 11:16:18 PM |

    It's amazing how much some of these companies will try to scam people with 'pharmacy grade' vitamins. It's easy for me to tell how much fish oil is oxidized by taste and how well it works and the best brand I've found is from trader joe's for 8 bucks a bottle. For stuff like vitamin C the process is so simple it's pretty much literally impossible to have any real difference brand to brand aside from how absorbable it is and again it's easy to tell when pills are not absorbing due to how they feel.

  • Clamence

    8/20/2009 12:26:19 AM |

    And we wonder why healthcare costs are spiraling out of control in america...

    What's sad, is the problem isn't limited to just pharmaceuticals, so many other areas like diagnostic imaging and durable medical goods are so much more expensive than they should be.

  • Dr. William Davis

    8/20/2009 1:40:55 AM |

    Do your part to reduce healthcare costs: Reject the idea that fish oil, niacin, and vitamin D should be costly prescription agents.

    Pay for them yourself for SUPERIOR preparations that you can obtain without a prescription. This small effort alone will save us all hundreds of millions of dollars.

  • Nameless

    8/20/2009 3:04:42 AM |

    Anyone know when Lovaza is going generic? I thought I read that perhaps by end of the year their exclusivity may be up, which should open up cheap prescription alternatives -- and sort of kill Lovaza's profits too.

  • Anonymous

    8/20/2009 3:09:24 AM |

    I use otc niacin at about $3 a bottle, and one of the doctors I work with asked me why I hadn't asked my doc for a prescription for Niaspan.
    I just didnt know where to begin.

    Jeanne

  • Anne

    8/20/2009 7:54:19 AM |

    Wow - I'm so surprised that there are worries about a national health care service in the US such as we have in the UK. Here, Lovaza (Omacor) costs the National Health Service £50 for 100 capsules, ie 50p per capsule !

    Of course that's not what patients pay. Patients who are charged prescription charges will pay  Â£7.20 per prescription of 100 capsules, and patients who don't pay prescriptions charges at all (approx 70% of patients), well they don't pay anything for their Lovaza....they have paid in their taxes for it already.

    But to me the biggest surprise is that the pharmacutical company that makes Lovaza charges so much less in the UK than it does in the US !

    Anne

  • Richard A.

    8/20/2009 6:32:00 PM |

    Another way to save on prescription drugs--pill splitting. Too often the smaller dose costs almost as much as the bigger dose. Getting the bigger pill and cutting it down to smaller doses can save a lot of money.

  • pyker

    8/20/2009 9:09:30 PM |

    I'm surprised we don't see scrips for "pharmaceutical-grade water", to wash these down.

  • Anonymous

    8/21/2009 2:21:12 AM |

    pyker, its called "bottled water"

  • JLL

    8/25/2009 1:38:15 PM |

    It's not really a problem that pharmacy grade fish oil is ridiculously expensive, as long as it's not illegal to sell cheaper fish oils too.

    In Europe, the trend seems to be that supplements are becoming available only in pharmacies, which can then charge extraordinary prices for everything.

  • Boris

    9/7/2009 1:22:32 PM |

    I have moderately high triglycerides at 255. My physician gave me a sample bottle of Lovazza to try which has 28 softgels. I have been taking one softgel a day.

    I have been looking into OTC fish oil supplements. Some are very diluted and some are very concentrated. Most break down the EPA and DHA content while others don't. I created a spreadsheet that collects the EPA and DHA content of several OTC fish oil supplement. In order to make a fair comparison, I adjusted my serving size for each brand name to give me about the same quantity of the essential fatty acids. The prices range from $0.11 per dosage to $1.76 per dosage.

    So once I figured out what's the most cost effective brand to buy now I have to worry and wonder about purity. Am I getting a less refined formula that will have heavy metals, PCBs, and other nasty chemicals? The words "triple distilled" mean nothing to me. I'd like to see "Contains no more than 0.010 PPM of arsenic" or something like that.

    The Lovazza might have the advantage here since the FDA probably won't let poisoned fish oil out. I have no idea what my effective price per dosage is with Lovazza since my sample bottle was free. My company takes a decent chunk of my pay for health care and I rarely use it. Maybe it's time I get my money's worth and get some subsidized Lovazza?

  • trinkwasser

    9/10/2009 2:51:21 PM |

    "I'm surprised we don't see scrips for "pharmaceutical-grade water", to wash these down."

    What, like this?

    http://www.marksdailyapple.com/bling-water/

  • Boris

    9/30/2009 4:29:47 PM |

    My one month experiment with Lovaza is over. I received a free sample bottle with 28 capsules last month from my physician. The recommended dosage was four a day but he told me to take one. I did that for one month. My triglycerides went down from 255 to 135 with no significant change in diet. My total cholesterol went down from 221 to 177, and it was all LDL. Unfortunately, my HDL levels stayed almost the same.

    So do I continue with Lovaza and get a prescription or do I get a high quality OTC like Omapure?

    I will see my physician tomorrow.

    Decisions, decisions, decisions!

  • moblogs

    3/24/2010 12:59:07 AM |

    Just want to add that Omacor (European Lovaza) costs £2 per day, while Triple Strength Omega 3 from a reputable company costs 12p per day in comparison, for roughly the same amount of EPA and DHA. You just have to take 6 capsules instead of 4.
    My jaw would've dropped if I hadn't been getting my vitamin D! Smile

  • buy jeans

    11/3/2010 9:50:53 PM |

    I can also go to Sam's Club and buy a bottle of their Triple-Strength fish oil with 900 mg omega-3 fatty acids per capsule at $18.99 per bottle of 180 capsules. That comes to 10.5 cents per capsule. That puts the price of fish oil from Sam's Club at 97.6% less cost compared to Lovaza for an equivalent quantity of omega-3 fatty acids.

Loading
Let's soak 'em with fish oil

Let's soak 'em with fish oil

If you don't think that charging drug prices for fish oil is wrong, take a look at a letter from an angry Heart Scan Blog reader:


Hello Dr. Davis,

My 44 year old brother had an MI [myocardial infarction, or heart attack] in June. He got pushed around due to "bad government insurance," a state-run program for the "uninsured": government pays 1/3, job pays 1/3, and individual pays 1/3.

What they didn't tell him is that there is no major medical coverage and little to no prescription coverage. We fought for 4 months to get him open heart surgery that the insurance was not going to pay for.

Now, with no assistance, terrible insurance, and no disability he has little to no income. He is a heavy equipment mechanic and is trying to be the "good American"-- take care of his bills, not file bankruptcy, etc.

Anyway, the doctors never seem to pay attention to what they prescribe. Lipitor was not working for him, due to side effects. Now they want to give him Zetia and Lovaza....Zetia at $114, and Lovoza is $169.85! Wow! For dead fish???? I think this is a little fishy! I looked up Lovaza, gee how nice, they will give you a $20 coupon....

Forget it, he can't afford this stuff. So I am enrolling in the Zetia program for him. And trying to get him OTC [over-the-counter] fish oil. The most prevalent fish oil around here (that I take myself is) Omega 3 Fish Oil that has EPA 410mg, DHA 274.

Thanks for your blog. It made me feel better that I wasn't the only one outraged by this stuff. I 've been a nurse for 20 years and it just never seems to get better. Thank you for your wisdom.

Sincerely JP, Tennessee



Had this reader not been aware that her brother could take fish oil as a nutritional supplement, he likely would have been denied the benefit of omega-3 fatty acids in slashing the risk for recurrent cardiovascular events. You and I can buy wonderfully safe and effective fish oil as a nutritional supplement, but there won't be a sexy drug representative to sell it, nor an expensive dinner and payment for a trip to Orlando to hear about it.

Comments (12) -

  • Richard A.

    2/8/2010 5:47:27 PM |

    Why expensive Zetia. Niacin appears to outperform Zetia.

    http://www.webmd.com/cholesterol-management/news/20091116/niacin-tops-zetia-in-cutting-artery-plaque

    While in this study the expensive Niaspan was used, you can by Slo-Niacin dirt cheap.

    http://www.costco.com/Browse/Product.aspx?Prodid=11118583

  • Ateronon

    2/8/2010 7:24:40 PM |

    Why do insurance companies pay for Lovaza? They are usually very picky and Lovaza would seem an obvious "soak" job?

    How did it get on approved drug lists?

  • Jenny

    2/9/2010 12:05:32 AM |

    Dr. Davis,

    Your correspondent should tell his brother to ditch the Zetia too. The research makes it clear it does not prevent heart attack and may worsen health. Statins appear to be helpful because of their impact on inflammation, not because they lower LDL cholesterol. Zetia lowers cholesterol in a mechanical way that has no impact on inflammation.

  • zach

    2/9/2010 1:16:17 AM |

    Why is a 44 year old being subjected to open heart surgery? Quacks.

  • Rick Loftus, M.D.

    2/9/2010 2:05:01 AM |

    As an internist not categorically opposed to statins (although I agree with starting with nutrition first, which is why I read this blog), there are generic alternatives for this person's brother. If my patients need Western drugs, I start with cheap generics whenever possible. Zetia has dubious benefits of ANY kind, and costs a fortune. And of course Dr. D is right that there are many cheaper sources of fish oil; I usually point my patients in that direction.

    I often feel "standard" American-style medical practice is intended to waste as much money as possible. People need to be able to trust their docs to execute plans that are not only based on the research evidence, but are cost effective. There is no culture of cost-effective medicine in this country, because health care was defined by the Americans as a for-profit arena.

    "Prescribe unto others as you would have them prescribe unto you."

  • Anonymous

    2/9/2010 4:39:50 AM |

    Lovaza fills a void created by bad government and insurance policy. According to IRS rules, over the counter supplements cannot be covered by many insurance handlers. My work's HSA is like this. Fish oil / omega-3 is technically considered an over the counter supplement. The folk making Lovaza more than understand the benefits of omega-3 and want to sell it to the folks who want their insurance to pay for it. So they made it into a "drug" and sell it as such. It's a brilliant marketing plan and it seems to be working for them. The sad part is that it is working! It shouldn't! Same thing goes with Lovastatin. Why not take a good red yeast rice? Oh well... you pay for what you don't know.

    -- Boris

  • Anne

    2/9/2010 8:04:37 AM |

    Your post, Dr Davis, seems more a call for better health care, the kind we here in the United Kingdom get under our National Health Service, than a call for different fish oils or different meds.

    The NHS does have it's problems, sure, but they're nothing like the problems this person you describe has.

  • tom

    2/9/2010 1:09:59 PM |

    It's ironic that her brother is trying to be a "good" American by paying his bills and not filing bankruptcy.
    If only his doctors, insurance companies, and drug mNUFcturers had a similar ethic.  It seems that for them, being a good American is maximizing their income regardless of who they take it from.
    Ordinary Americans have been sold this "good" American concept from birth.  It's propaganda.  Far too many special interests have used it to enrich only themselves.

  • Alfredo E.

    2/15/2010 9:09:26 PM |

    Your brother should not be paying anything for drugs to lower cholesterol.

    Cholesterol is not the enemy, nor is saturated fat.

    The real enemy is chronic inflammation that comes from several sources but mainly from a high grain diet (too much omega 6).

    Please, read http://www.omega-3-fish-oil-wonders.com/good-fats.html

    Best wishes,
    Alfredoe

  • beverly

    3/3/2010 3:19:19 PM |

    I have read with interest the comments concerning Lovaza. I was put on it in 2008. I have tried numerous times to ask GSK through emails & ph calls the calorie make up in the gelcap. No one seems to know! Not the Doctor who put me on it, the pharmacist, or anyone from GSK!!! As a diabetic who has lost 140 lbs, following my diet plan is very important to me. Any suggestions on who can make them give up the big calorie secret?
    Thanks,
    Beverly

  • buy jeans

    11/3/2010 10:20:24 PM |

    Had this reader not been aware that her brother could take fish oil as a nutritional supplement, he likely would have been denied the benefit of omega-3 fatty acids in slashing the risk for recurrent cardiovascular events. You and I can buy wonderfully safe and effective fish oil as a nutritional supplement, but there won't be a sexy drug representative to sell it, nor an expensive dinner and payment for a trip to Orlando to hear about it.

  • Dave

    5/31/2011 4:43:42 AM |

    Beverly,
    A rough estimate for the caloric content of each Lovaza capsule would be approximately 8-10 calories.  Since each capsule contains roughly 1 gram of total fat.

Loading