Is Fish Oil a Natural Blood Thinner?

Fish oil supplements can contribute to a healthy lifestyle.

Fish oil supplements have become a common item at pharmacies and natural foods stores across the nation. The growing use of this supplement is a reflection of the ongoing battle to fight cardiovascular disease in the United States. Omega-3 fatty acids found in fish oil are known to reduce inflammation and decrease your risk of chronic degenerative diseases. Omega-3 fatty acids also influence your ability to form blood clots and may have a natural blood-thinning effect.

Omega Fatty Acids

Two of the omega fatty acids commonly found in supplements are essential fatty acids, meaning that your body doesn't manufacture them. You must consume them in your diet. Omega-6 fatty acid is ubiquitous in the American diet, as it is found in all animal-based foods such as meat, eggs, poultry and dairy products. Omega-3 fatty acids are not as common in the American diet. They are primarily found in fish and nuts, which are less plentiful in the American diet. This disparity between omega-6 and omega-3 may be partially to blame for the epidemic levels of heart disease in the U.S. Omega-6 increases inflammation, whereas omega-3 decreases it. Omega-3 also decreases platelet aggregation, thus discouraging the formation of blood clots and acting as a natural blood thinner.

Blood Thinning Advantages

In some cases, fish oil's ability to decrease clot formation can be considered an asset. Fish oil's blood-thinning effect may help decrease your risk of thrombosis, a condition in which a blood clot breaks free and circulates in your bloodstream, finally landing in your heart, where it can cause myocardial infarction. A thrombosis that reaches your brain can cause stroke. The Linus Pauling Institute states that in some cases fish oil has been found to decrease the risk of ischemic stroke, which occurs when a blood clot blocks an artery to your brain.

Blood Thinning Risks

In other cases, the decreased clotting caused by fish oil can be considered undesirable, and even dangerous. If you're already taking blood-thinning medications such as aspirin, warfarin or clopidrogel, the added blood-thinning effect of fish oil may hamper your body's ability to stop bleeding from a wound. Those with bleeding disorders such as hemophilia may find their condition exacerbated by high dosages of fish oil. According to the University of Maryland Medical Center, you should not take fish oil with any blood-thinning medications unless under the supervision of your physician.


In the July 2004 issue of the journal "American Family Physician," Dr. Maggie Covington states that there have been no documented cases of abnormal bleeding caused by taking fish oil. Regardless, you should not take any risks with fish oil if you are on blood-thinning medications or have a bleeding disorder. UMMC advises you to keep your daily intake of fish oil below 3 g, in order to avoid increased bleeding risk.