Maybe they should just replace the warfarin with the fish oil...Yes, that's why the use of warfarin is very strictly monitored. The regular warfarin clinics test for levels of the clotting factors in the blood and the warfarin dose is adjusted accordingly. Everyone is different and have different diets and treament with warfarin is on an individual level. This contrasts with a drug like Apixaban which acts differently and which can be used in set doses. Warfarin doses always start by looking at your individual blood clotting process and repeated trips back to the clinic are required. Here is a case of a woman who suddenly decides to double her intake of fish oil:
"This case reveals a significant rise in INR after the dose of concomitant fish oil was doubled. Patients undergoing anticoagulation therapy with warfarin should be educated about and monitored for possible drug-herb interactions."
Fish oil interaction with warfarin.