There may be a dose-related effect of omega-3 fatty acids on atrial fibrillation risk. In high doses there appeared to be an increase in risk for atrial fibrillation in the omega-3 groups (versus control) in both trials.
Respiratory failure; changes in the heart's electrical activity that can cause deadly abnormal rhythms; life-threatening low blood pressure caused by dehydration; acute liver failure; low blood cell counts that require blood transfusion; as well as severe vomiting and diarrhea.