Fish Oil and Bleeding Risk

Introduction to Bleeding Risk

The American College of Cardiology and other guideline societies suggest that fish oil supplementation does not cause clinically significant bleeding in most patients, including those taking anticoagulants like warfarin, aspirin, or heparin, based on the highest quality evidence from large randomized controlled trials 1, 2.

The European Food Safety Authority recommends that long-term supplemental intakes of EPA and DHA combined up to 5g daily do not increase the risk of spontaneous bleeding or bleeding complications 4.
Supplemental intakes of EPA alone up to 1.8g daily do not raise safety concerns for adults 4.

The American Heart Association notes that fish oil (1-2g daily) can increase INR and has antiplatelet effects when combined with warfarin, and therefore INR should be monitored closely when initiating fish oil or changing doses in warfarin-treated patients 5.

The European Society of Cardiology recommends that patients receiving ibrutinib (for chronic lymphocytic leukemia) should avoid fish oil supplements due to reported epistaxis when these agents are combined 4.

For patients on anticoagulants, the American College of Cardiology recommends that fish oil can be used safely at standard doses (1-2g daily) with appropriate INR monitoring for warfarin patients 5.
The American Society of Anesthesiology's recommendation to discontinue dietary supplements 1-2 weeks before surgery is not supported by high-quality evidence for fish oil specifically, and routine discontinuation is not necessary before cardiac surgery based on bleeding risk alone 1, 2.

The National Lipid Association recommends that doses above 3 grams daily require physician supervision due to potential bleeding risk at very high doses, although this is based on evidence from Praxis Medical Insights, a non-preferred source 6, 7, a better source is the European Food Safety Authority which states that doses up to 5g daily do not increase bleeding risk 4.