What is it?
Cod liver oil is used for high cholesterol, high triglycerides, kidney disease in people with diabetes, high blood pressure, heart disease, osteoarthritis, depression, an autoimmune disease called systemic lupus erythematosus (SLE), glaucoma, and middle ear infections (otitis media).
Some people put cod liver oil on their skin to speed wound healing.
When taken in appropriate doses by mouth, cod liver oil seems to help lower high triglycerides (a type of blood fat), lower high blood pressure, and treat some symptoms of kidney disease related to diabetes. It doesn’t seem to lower high cholesterol or reduce arthritis pain. Other uses are still under investigation.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for COD LIVER OIL are as follows:
Likely effective for…
- Lowering blood fats called triglycerides. Taking cod liver oil by mouth can reduce triglyceride levels by 20% to 50% in people with high triglyceride levels.
Possibly effective for…
- High blood pressure. Taking cod liver oil by mouth seems to lower blood pressure (both numbers) a small, but important, amount in people with mild high blood pressure.
- Kidney disease in people with type 2 diabetes. Taking cod liver oil seems to reduce protein in the urine, a marker for kidney disease severity.
Possibly ineffective for…
- Cholesterol disease that runs in families (familial hypercholesterolemia).
Insufficient evidence to rate effectiveness for…
- Depression. There is some evidence that people who take cod liver oil have fewer symptoms of depression than other people.
- Irregular heartbeat in people with heart disease. There is some early evidence that cod liver oil might help to prevent certain types of irregular heartbeat.
- Ear infections in young children. Preliminary research suggests that taking cod liver oil along with a children’s multivitamin-mineral product containing selenium might prevent or decrease the number of ear infections in young children.
- Heart disease.
- Systemic lupus erythematosus (SLE).
- Wound healing.
- Other conditions.
More evidence is needed to rate cod liver oil for these uses.
How does it work?
Are there safety concerns?
High doses are POSSIBLY UNSAFE. They might keep blood from clotting and can increase the chance of bleeding. Vitamin A and vitamin D levels might also become too high with high doses of cod liver oil. High doses might also cause nausea and loose stools.
The safety of cod liver oil when used on the skin is unknown.
Special precautions & warnings:
Pregnancy and breast-feeding: Not enough is known about the use of cod liver oil during pregnancy and breast-feeding. Stay on the safe side and avoid use.
High blood pressure: Cod liver oil can lower blood pressure and might cause blood pressure to go too low if used along with medications for high blood pressure. Be careful when using cod liver oil if you are taking high blood pressure drugs.
Are there interactions with medications?
- Medications for high blood pressure (Antihypertensive drugs)
- Cod liver oil seems to decrease blood pressure. Taking cod liver oil along with medications for high blood pressure might cause your blood pressure to go too low.
Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), amlodipine (Norvasc), hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.
- Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
- Cod liver oil might slow blood clotting. Taking cod liver oil along with medications that also slow clotting might increase the chances of bruising and bleeding.
Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), dipyridamole (Persantine), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.
Are there interactions with herbs and supplements?
- Herbs and supplements that might slow blood clotting
- Cod liver oil might slow blood clotting. Using cod liver oil with herbs and supplements that also slow blood clotting might increase the chance of bruising and bleeding in some people. These herbs include angelica, borage seed oil, clove, danshen, garlic, ginger, ginkgo, red clover, turmeric, willow, and others.
Are there interactions with foods?
- There are no known interactions with foods.
What dose is used?
- For lowering triglycerides: 20 mL of cod liver oil per day.
- For high cholesterol: 30 mL of cod liver oil per day.
- For lowering blood pressure: 20 mL of cod liver oil per day.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
- Raeder MB, Steen VM, Vollset SE, Bjelland I. Associations between cod liver oil use and symptoms of depression: The Hordaland Health Study. J Affect Disord 2007;101:245-9. View abstract.
- Farmer A, Montori V, Dinneen S, Clar C. Fish oil in people with type 2 diabetes mellitus. Cochrane Database Syst Rev 2001;3:CD003205. View abstract.
- Linday LA, Dolitsky JN, Shindledecker RD, Pippenger CE. Lemon-flavored cod liver oil and multivitamin-mineral supplement for the secondary prevention of otitis media in young children: pilot research. Ann Otol Rhinol Laryngol 2002:111:642-52.. View abstract.