Patients who take large doses of fishoil and warfarin together may be atincreased risk of bleeding, especially ifthey are elderly. A recently publishedcase report illustrates this problem: a75-year-old patient who experienced aminor fall subsequently developed asubdural hematoma that required acraniotomy. The patient was takingwarfarin, aspirin, and fish oil at a doseof 6 g daily.
The mechanism of action of the long-chainfatty acids in fish oil is not wellunderstood, but they are thought tohave antiplatelet and anticoagulantproperties. Several studies have demonstratedan increase in bleeding timewith doses of fish oil >2 g/day. A synergisticeffect on bleeding time with anaspirin/fish oil combination has alsooccurred in studies.
The FDA has concluded that fish oilis safe as a dietary supplement at dosesof less than 3 g/day. Patients who areusing the supplement for cardiac indicationsor treatment of hypertriglyceridemia,however, may be treatedwith higher doses.
Dr. Garrett is a clinical pharmacistpractitioner at Cornerstone HealthCare in High Point, NC.