What is it?
Cod liver oil is used as a source of vitamin A and vitamin D, and to treat high cholesterol and high triglyceride levels, kidney disease in people with diabetes, high blood pressure, heart disease, osteoarthritis, rheumatoid arthritis, depression, an autoimmune disease called systemic lupus erythematosus (SLE), glaucoma, and middle ear infections (otitis media). It is also used to prevent respiratory infections, and an age-related eye condition called macular degeneration.
Some people put cod liver oil on their skin to speed healing of wounds, burns, and rashes.
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:
Insufficient evidence to rate effectiveness for...
- Age-related macular degeneration. People who eat a lot of fish and take cod liver oil don't have a lower risk of developing this condition compared to people who just eat a lot of fish.
- Irregular heartbeat. Taking cod liver oil by mouth might reduce a specific type of irregular heartbeat in some people. But it's not known if this reduces the risk of heart-related death. Taking cod liver oil by mouth does not seem to reduce irregular heartbeat in men with irregular heartbeat after a heart attack.
- Depression. Taking cod liver oil has been linked with a 29% lower chance of older adults having depression symptoms.
- High cholesterol levels in the blood. Taking cod liver oil by mouth doesn't lower cholesterol levels in people with high cholesterol. But it might increase "good" high-density lipoprotein cholesterol levels in people with type 1 diabetes and high cholesterol. Also it might lower blood fats called "triglycerides" in men who have had a heart attack. But cod liver oil doesn't improve these outcomes in people with an inherited form of high cholesterol.
- High blood pressure. Taking cod liver oil by mouth seems to slightly lower blood pressure in healthy people and those with slightly high blood pressure. But it's not clear if this reduction is clinically meaningful for people with very high cholesterol.
- Inflammatory bowel disease. Some people with inflammatory bowel disease have joint pain. Taking cod liver oil might reduce joint pain in some people with this condition.
- Osteoarthritis. Taking cod liver oil along with an NSAID doesn't reduce swelling in people with osteoarthritis better than taking an NSAID alone.
- Ear infections in young children. Taking cod liver oil and a multivitamin might reduce the need to use medicine to treat ear infections in young children by about 12%.
- Airway infections. Giving young children cod liver oil and a multivitamin seems to reduce the number of doctor's office visits for airway infections.
- Rheumatoid arthritis. Taking cod liver oil might decrease pain, morning stiffness, and swelling in some patients with rheumatoid arthritis. Also, taking cod liver oil and fish oil seems to reduce the need to use medicine to treat joint swelling in people with this condition.
- Vitamin D deficiency. Taking cod liver oil seems to increase blood levels of vitamin D in some people. But it's not clear if cod liver oil increases vitamin D to normal levels in people with low levels of vitamin D.
- Wound healing.
- Other conditions.
How does it work?
Are there safety concerns?
High doses of cod liver oil 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.
The safety of cod liver oil when used on the skin is unknown.
Special precautions & warnings:Pregnancy and breast-feeding: Cod liver oil is POSSIBLY SAFE when used in amounts that provide no more than the recommended daily intakes of vitamin A and vitamin D. Cod liver oil is POSSIBLY UNSAFE when taken in larger amounts. Women who are pregnant or breast-feeding should not take cod liver oil that provides more than about 3000 mcg of vitamin A and 100 mcg of vitamin D.
Diabetes: There has been some concern that cod liver oil or other fish oils might increase blood sugar in people with diabetes. But there is no strong research that supports this concern. 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 lower blood pressure (Hypotensive herbs and supplements)
- Cod liver oil might lower blood pressure. It has the potential to add to blood pressure lowering effects of other herbs and supplements that also lower blood pressure. Other herbs and supplements that can lower blood pressure include andrographis, casein peptides, cat's claw, coenzyme Q10, L-arginine, lycium, stinging nettle, theanine, and others.
- 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?
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
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