Cod Liver Oil & Warfarin

Publication Date: 
Mon, 09/02/2013
By: Alere Staff

Cod Liver Oil & Warfarin

Cod liver oil is an old school remedy for many ailments, touted as a treatment for eczema, arthritis and heart disease.1 Known also as omega-3 fatty acid source, cod liver oil is receiving glowing reviews for its role in reducing high triglycerides in people who also often suffer from high cholesterol.1 Estimates of 20-50% reductions in hyper-triglycerides have been reported.

Patients should communicate with their healthcare professionals before starting or stopping cod liver oil or omega-3 fish oil products. The health benefit of reducing triglycerides and possibly blood pressure is promising but the risk of increased bleeding is possible in some patient.

Cod liver oil has been associated with an increased risk of bleeding.2 Patients taking warfarin should increase their testing frequency to determine the effect of cod liver oil on INR test results. Also, cod liver oil is a high source of vitamin D at 1360 units per serving in 1 tablespoon.3 Concern has been raised about a possible interaction between vitamin D and warfarin, but the potential for increased activity of warfarin due to vitamin D has not been confirmed by any substantial research.4 Normal amounts of vitamin D should not affect INR test results.

The U.S. Food & Drug Administration (FDA) considers cod liver oil as generally regarded as safe (GRAS) when used as directed. Women who are pregnant or who might become pregnant are advised against using cod liver oil.

Patient who test weekly are in the best position to evaluate the effects of diet or supplements such as cod liver oil.

Increasing testing frequency is recommended when starting or stopping any new medication or dietary supplement including vitamins. To safely evaluate the effect of cod liver oil on an INR test result, patients should keep their diet consistent and use the Vitamin K Food Diary® Log.

Increasing testing frequency is recommended when making any changes to your diet, medication, etc. Studies have shown that increasing testing frequency with weekly testing of INR improves patient safety and helps keep the drug in its therapeutic effective zone.5,6 Weekly testing was shown to be the most effective testing frequency.5 Medicare and many private/commercial insurance reimburse patients for weekly patient self-testing.7 Go to the Getting Started page or call Alere at 1.800.504.4032 for more information about testing your INR at home.


  1. National Institute of General Medical Sciences. The Big, Fat World of Lipids. Posted August 9, 2012. Accessed June 3, 2013.
  2. Jensen T, Stender S, Goldstein K, Hølmer G, and Deckert T. Partial normalization by dietary cod-liver oil of increased microvascular albumin leakage in patients with insulin-dependent diabetes and albuminuria. N Engl J Med. 1989 Dec 7;321(23):1572-7.
  3. US Department of Agriculture, Agricultural Research Service. USDA Nutrient Database for Standard Reference, Release 22, 2009.
  4. Schrogie JJ. Coagulopathy and Fat-Soluble Vitamins. JAMA. 1975;232(1):19.
  5. Am J Manag Care. 2014;20(3):202-209.
  6. Heneghan C., et al. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. 2006. Lancet, 367, 404-11.
  7. Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management  (CAG-00087R) [Memorandum]. 2008. Baltimore, MD.