Fish oil can be obtained from eating fish or by taking supplements. Fish that are especially rich in the beneficial oils known as omega-3 fatty acids include mackerel, herring, tuna, salmon, cod liver, whale blubber, and seal blubber. Two of the most important omega-3 fatty acids contained in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Make sure to see separate listings on EPA and DHA, as well as Cod Liver Oil, and Shark Liver Oil.
Fish oil is FDA approved to lower triglycerides levels, but it is also used for many other conditions. It is most often used for conditions related to the heart and blood system. Some people use fish oil to lower blood pressure, triglycerides and cholesterol levels. Fish oil has also been used for preventing heart disease or stroke, as well as for clogged arteries, chest pain, irregular heartbeat, bypass surgery, heart failure, rapid heartbeat, preventing blood clots, and high blood pressure after a heart transplant.
Fish oil is also used to for many kidney-related problems including kidney disease, kidney failure, and kidney complications related to diabetes, cirrhosis, Berger's disease (IgA nephropathy), heart transplantation, or using the drug called cyclosporine.
Fish may have earned its reputation as "brain food" because some people eat fish to help with depression, bipolar disorder, psychosis, attention deficit-hyperactivity disorder (ADHD), Alzheimer's disease, developmental coordination disorder, migraine headache, epilepsy, schizophrenia, post-traumatic stress disorder, and mental impairment.
Some people use fish oil for dry eyes, cataracts, glaucoma, and age-related macular degeneration (AMD), a very common condition in older people that can lead to serious sight problems.
Fish oil is taken by mouth for stomach ulcers caused by Helicobacter pylori (H. pylori), inflammatory bowel disease, pancreatitis, an inherited disorder called phenylketonuria, allergy to salicylate, Crohn's disease, Behcet's syndrome, and Raynaud's syndrome.
Women sometimes take fish oil to prevent painful periods; breast pain; and complications associated with pregnancy such as miscarriage (including that caused by a condition called antiphospholipid syndrome), high blood pressure late in pregnancy, early delivery, slow infant growth, and to promote infant development.
Fish oil is also taken by mouth for weight loss, exercise performance and muscle strength, muscle soreness after exercise, pneumonia, cancer, lung disease, seasonal allergies, chronic fatigue syndrome, and for preventing blood vessels from re-narrowing after surgery to widen them.
Fish oil is also used for diabetes, prediabetes, asthma, a movement and coordination disorder called dyspraxia, dyslexia, eczema, autism, obesity, weak bones (osteoporosis), rheumatoid arthritis (RA), osteoarthritis, psoriasis, an autoimmune disease called systemic lupus erythematosus (SLE), multiple sclerosis, HIV/AIDS, cystic fibrosis, gum disease, Lyme disease, sickle cell disease, and preventing weight loss caused by some cancer drugs.
Fish oil is used intravenously (by IV) for scaly and itchy skin (psoriasis), blood infection, cystic fibrosis, pressure ulcers, and rheumatoid arthritis (RA).
Fish oil is applied to the skin for psoriasis.
Natural Medicines 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 Fish Oil are as follows:
Asthma. Some research suggests that fish oil supplements might help TREAT some asthma symptoms, but results are not consistent. Some research shows that taking fish oil improves breathing and reduces the need for medication, but other research suggests that fish oil does not reduce the severity of asthma is children.
It is also not clear if fish oil can help PREVENT asthma. Some early research suggests that mothers who take fish oil supplements daily during pregnancy reduce the risk of asthma in their children by 35% to 63%. But, fish oil does not seem to provide any benefits when taken while breastfeeding.
More evidence is needed to rate fish oil for these uses.
A lot of the benefit of fish oil seems to come from the omega-3 fatty acids that it contains. Interestingly, the body does not produce its own omega-3 fatty acids. Nor can the body make omega-3 fatty acids from omega-6 fatty acids, which are common in the Western diet. A lot of research has been done on EPA and DHA, two types of omega-3 acids that are often included in fish oil supplements.
Omega-3 fatty acids reduce pain and swelling. This may explain why fish oil is likely effective for psoriasis and dry eyes. These fatty acids also prevent the blood from clotting easily. This might explain why fish oil is helpful for some heart conditions.
Fish oil is LIKELY SAFE for most people when taken by mouth in low doses (3 grams or less per day). There are some safety concerns when fish oil is taken in high doses. Taking more than 3 grams per day might keep blood from clotting and can increase the chance of bleeding.
High doses of fish oil might also reduce the immune system's activity, reducing the body's ability to fight infection. This is a special concern for people taking medications to reduce their immune system's activity (organ transplant patients, for example) and the elderly.
Only take high doses of fish oil while under medical supervision.
Fish oil can cause side effects including belching, bad breath, heartburn, nausea, loose stools, rash, and nosebleeds. Taking fish oil supplements with meals or freezing them can often decrease these side effects.
Fish oil is POSSIBLY SAFE when injected intravenously (by IV) in the short-term. Fish oil or omega-3 fatty acid solutions have been safely used for 1 to 4 weeks.
Consuming large amounts of fish oil from some DIETARY sources is POSSIBLY UNSAFE. Some fish meats (especially shark, king mackerel, and farm-raised salmon) can be contaminated with mercury and other industrial and environmental chemicals. Fish oil supplements typically do not contain these contaminants.
Children: Fish oil is POSSIBLY SAFE when taken by mouth appropriately. Fish oil has been used safely through feeding tubes in infants for up to 9 months. But young children should not eat more than two ounces of fish per week. Fish oil is POSSIBLY UNSAFE when consumed from dietary sources in large amounts. Fatty fish contain toxins such as mercury. Eating contaminated fish frequently can cause brain damage, mental retardation, blindness and seizures in children.
Pregnancy and breast-feeding: Fish oil is LIKELY SAFE when taken by mouth appropriately. Taking fish oil during pregnancy does not seem to affect the fetus or baby while breast-feeding. Women who are pregnant or who may become pregnant, and nursing mothers should avoid shark, swordfish, king mackerel, and tilefish (also called golden bass or golden snapper), as these may contain high levels of mercury. Limit consumption of other fish to 12 ounces/week (about 3 to 4 servings/week). Fish oil is POSSIBLY UNSAFE when dietary sources are consumed in large amounts. Fatty fish contain toxins such as mercury.
Bipolar disorder: Taking fish oil might increase some of the symptoms of this condition.
Liver disease: Fish oil might increase the risk of bleeding in people with liver scarring due to liver disease.
Depression: Taking fish oil might increase some of the symptoms of this condition.
Diabetes: There is some concern that taking high doses of fish oil might make the control of blood sugar more difficult.
Familial adenomatous polyposis: There is some concern that fish oil might further increase the risk of getting cancer in people with this condition.
High blood pressure: Fish oil can lower blood pressure and might cause blood pressure to drop too low in people who are being treated with blood pressure-lowering medications.
HIV/AIDS and other conditions in which the immune system response is lowered: Higher doses of fish oil can lower the body's immune system response. This could be a problem for people whose immune system is already weak.
An implanted defibrillator (a surgically placed device to prevent irregular heartbeat): Some, but not all, research suggests that fish oil might increase the risk of irregular heartbeat in patients with an implanted defibrillator. Stay on the safe side by avoiding fish oil supplements.
Fish or seafood allergy: Some people who are allergic to seafood such as fish might also be allergic to fish oil supplements. There is no reliable information showing how likely people with seafood allergy are to have an allergic reaction to fish oil. Until more is known, advise patients allergic to seafood to avoid or use fish oil supplements cautiously.
Interaction Rating = Moderate Be cautious with this combination
Talk with your health provider.
Birth control pills might interfere with the triglyceride-lowering effects of fish oil.
Some of these drugs include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.
Interaction Rating = Minor Be watchful with this combination
Talk with your health provider.
Some fish oil products contain small amounts of a fatty acid that is believed to stop certain chemotherapy drugs from working. However, the amount of this fatty acid in most fish oil products is probably too low to be a concern. Until more is known, you do not need to stop taking fish oil if you are also taking medications for cancer.
Interaction Rating = Moderate Be cautious with this combination.
Talk with your health provider.
Using fish oil with drugs that lower blood pressure may increase the effects of these drugs and may lower blood pressure too much.
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.
Interaction Rating = Minor Be watchful with this combination.
Talk with your health provider.
Using fish oil with medications that slow clotting may increase the risk of bleeding. However, conflicting data exists. Until more is known, use cautiously in combination with medications that slow blood clotting.
Some of these drugs include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), dipyridamole (Persantine), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.
Orlistat (Xenical, Alli) might keep the beneficial fatty acids in fish oil from being absorbed by the body. Taking fish oil and orlistat (Xenical, Alli) at least 2 hours apart may keep this from happening.
Warfarin (Coumadin) is used to slow blood clotting. Fish oil also might slow blood clotting. Taking fish oil with warfarin might slow blood clotting too much and increase the risk of bleeding. However, conflicting results suggests that fish oil does not increase the effects of warfarin. Until more is known, use cautiously in combination with warfarin. Have your blood checked regularly, as your dose of warfarin (Coumadin) might need to be changed.
Fish 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 Q-10, L-arginine, lycium, stinging nettle, theanine, and others.
High doses of fish oil seem to slow blood clotting. Taking fish oil with other herbs that slow clotting might cause bleeding in some people. These herbs include angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, red clover, turmeric, willow, and others.
Fish oil can reduce vitamin E levels. Researchers aren't sure whether fish oil keeps vitamin E from being absorbed from food or whether it causes the body to use up vitamin E faster than it should.
There are no known interactions with foods.
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