If you’re taking omega-3 supplements and have a heart condition—or know someone who does—you’ve probably wondered whether combining fish oil with blood thinners is safe. It’s a common concern, especially since blood thinners reduce clot formation and omega-3s are often said to "thin" the blood. But what does the science really say?
Why Are Blood Thinners Prescribed?
Blood thinners help prevent clots that can lead to heart attack, stroke, or other serious complications. There are two main types:
-
Anticoagulants: Like warfarin and heparin, these inhibit clotting factors.
-
Antiplatelets: Like aspirin and clopidogrel (Plavix), these prevent platelets from sticking together.
Doctors often caution against mixing these medications with other drugs or supplements, including fish oil, due to potential bleeding risks. Common culprits include certain antibiotics, antidepressants, anti-inflammatories, and herbal products like ginseng or ginkgo biloba.
But where does fish oil really stand?
Omega-3s: Nature’s “Blood Thinner”?
Omega-3 fatty acids—specifically EPA and DHA—gained attention in the 1970s when scientists Bang and Dyerberg observed that Greenland Inuit had lower heart attack rates, possibly due to their omega-3-rich diet. Subsequent studies confirmed that fish oil can reduce platelet aggregation, leading to a slight increase in bleeding time. This was seen as a protective mechanism against heart attacks.
However, these early findings sparked a longstanding myth that omega-3s significantly increase bleeding risk, especially when combined with medications. The FDA has since reviewed this concern and concluded that prescription omega-3s do not pose a significant bleeding risk.
What the Latest Research Shows
Recent studies have provided even stronger evidence that omega-3s do not increase bleeding risk—even in surgical settings or when taken with blood thinners.
Key Findings:
-
Systematic Review (2022): Found no increased risk of bleeding during or after surgery in patients taking fish oil. The conclusion? Discontinuing fish oil before surgery is unnecessary.
-
OPERA Trial (Published in Circulation): Over 1,500 cardiac surgery patients were studied. Those who received high-dose omega-3s (6.5–8 g over a few days before surgery, followed by 1.7 g/day) had:
-
No increase in major bleeding
-
Fewer blood transfusions required
-
Lower risk of bleeding at higher omega-3 blood levels
-
According to Dr. Bill Harris, PhD—founder of OmegaQuant and co-inventor of the Omega-3 Index—this suggests the longstanding recommendations to stop fish oil before surgery should be reconsidered.
Understanding the Omega-3 Index
The Omega-3 Index is a measure of EPA and DHA as a percentage of total fatty acids in red blood cell membranes. An index of 8–12% is considered optimal for cardiovascular protection. Most Americans fall far below this range.
By achieving and maintaining an Omega-3 Index above 8%, individuals significantly reduce their risk of fatal heart disease. This long-term biomarker is far more reliable than measuring omega-3 intake from diet alone.
Should You Worry About Bleeding Risk?
Based on the latest evidence, the answer is no—especially when omega-3s are taken at recommended doses and under medical supervision. If you’re on blood thinners and are considering omega-3 supplements, consult with your healthcare provider. But current research strongly supports that omega-3s can be safely used alongside heart medications.
Final Takeaway
Omega-3s are essential for heart, brain, and joint health—and new science confirms they do not significantly increase bleeding risk, even when used with blood thinners. If you're aiming to protect your heart and maintain healthy circulation, omega-3s should remain a trusted part of your wellness plan.
Be sure to check your Omega-3 Index to see if you’re in the protective range—and if not, consider increasing your intake through diet or supplements.
