What is it?
Fish oil can be obtained by eating fish or taking supplements. Fish that are especially rich in the beneficial oils known as omega-3 fatty acids include mackerel, herring, tuna, and salmon. Two of the most important omega-3 fatty acids contained in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
Some fish oil products are approved by the US Food and Drug Administration (FDA) as prescription medications to lower triglycerides levels. Fish oil is also available as a supplement. Fish oil supplements do not contain the same amount of fish oil as prescription products, so they cannot be used in place of prescription products. Fish oil supplements are sometimes used for heart health and mental health, but there is no strong evidence to support most of these uses.
Do not confuse fish oil with EPA, DHA, cod liver oil, flaxseed oil, krill oil, or shark liver oil. See the separate listings for these ingredients.
Effective for …
- High levels of fats called triglycerides in the blood (hypertriglyceridemia). Most research shows that fish oil can reduce triglyceride levels by 20% to 50%. The effects of fish oil are greater in people with higher triglyceride levels. Also, taking larger amounts of fish oil result reduce triglyceride levels by a greater amount. But fish oil seems to have a smaller effect compared to drugs called fibrates. Certain fish oil preparations, including Lovaza, Omtryg, and Epanova, are approved as prescription drugs for treating very high triglyceride levels. These products are most often taken at a dose of 4 grams daily. This provides about 3.5 grams of omega-3 fatty acids per day. While some non-prescription fish oil supplements have also shown benefit in research, some experts discourage people from using these products. Often these products contain less omega-3 fatty acids than the prescription fish oil products. As a result, people would need to take as many as 12 capsules per day of fish oil supplements to get the same effect as prescription fish oil. Fish oil supplements don’t seem to lower triglycerides in children and teens with high triglyceride levels. But these studies were small, so larger higher quality studies are needed to confirm.
Possibly Effective for …
- A procedure to open a blocked or narrowed blood vessel (angioplasty). Research suggests that fish oil decreases the rate of blood vessel re-blockage by up to 45% when given for at least 3 weeks before an angioplasty and continued for one month thereafter. But, when given for 2 weeks or less before angioplasty, it doesn’t seem to have any effect.
- Involuntary weight loss in people who are very ill (cachexia or wasting syndrome). Taking a high dose of fish oil seems to slow weight loss in some cancer patients. Low doses of fish oil don’t seem to have this effect. Some researchers believe fish oil slows cancer-related weight loss by fighting depression and improving the mood of people with cancer.
- Kidney damage caused by the drug cyclosporine. Cyclosporine is a medication that reduces the chance of organ rejection after an organ transplant. Taking fish oil seems to prevent kidney damage in people taking this drug. Fish oil also seems to improve kidney function during the recovery phase following the rejection of a transplanted organ in people taking cyclosporine.
- Menstrual cramps (dysmenorrhea). Research shows that taking fish oil, alone or with vitamin B12 or vitamin E, can improve painful periods and reduce the need for pain medications in women with menstrual cramps.
- Heart failure. Higher intake of fish oil from foods has been linked with a reduced risk of heart failure. Eating 1-2 servings of non-fried fish per week is recommended. It’s too soon to know if taking fish oil supplements helps prevent heart failure. But early research shows that fish oil supplements might reduce adverse outcomes such as hospital admissions or death in people that already have heart failure.
- Abnormal levels of blood fats in people with HIV/AIDS. Some research suggests that taking fish oil reduces triglyceride levels in people with abnormal cholesterol levels caused by HIV/AIDS treatment. Taking fish oil might also reduce total cholesterol levels in these people, although results are inconsistent.
- High blood pressure. Fish oil seems to slightly lower blood pressure in people with moderate to very high blood pressure. Some types of fish oil might also reduce blood pressure in people with slightly high blood pressure, but results are inconsistent. Fish oil seems to add to the effects of some, but not all, blood pressure-lowering medications. However, it doesn’t seem to reduce blood pressure in people with uncontrolled blood pressure who are already taking blood pressure-lowering medications.
- A condition that slowly leads to kidney disease (IgA nephropathy). Some research shows that long-term but not short-term use of fish oil can slow the loss of kidney function in high-risk patients with IgA nephropathy. Fish oil might have greater effects when taken at higher doses. Also, it might be most effective in people with IgA nephropathy who have higher levels of protein in the urine.
- Build up of fat in the liver in people who drink little or no alcohol (nonalcoholic fatty liver disease or NAFLD). Most research shows that fish oil might reduce liver fat and improve liver health in people with NAFLD.
- A mental disorder marked by hallucinations and delusion (psychosis). Some research shows that taking a fish oil supplement might help prevent full psychotic illness from developing in teenagers and young adults with mild symptoms. These effects of fish oil have not been tested in older people.
- Rheumatoid arthritis (RA). Taking fish oil by mouth, alone or together with the drug naproxen (Naprosyn), seems to help improve symptoms of RA. People who take fish oil can sometimes reduce their use of pain medications. Also, administering fish oil intravenously (by IV) reduces swollen and tender joints in people with RA.
Possibly Ineffective for …
- Chest pain (angina). Research suggests that taking fish oil supplements does not reduce the risk of death or improve heart health in people with chest pain. Some evidence even suggests that fish oil supplements might actually increase the risk of heart-related death in people with chest pain.
- Hardening of the arteries (atherosclerosis). Some research shows that taking fish oil supplements might slightly reduce the progression of atherosclerosis. But most research shows that fish oil doesn’t slow the progression or improve symptoms of atherosclerosis.
- Eczema (atopic dermatitis). Research shows that fish oil does not improve eczema. Most research also shows that taking fish oil during pregnancy doesn’t PREVENT eczema in the child. Giving fish oil to an infant also doesn’t seem to prevent eczema in children. But children who eat fish at least once weekly from the age of 1-2 years seem to have a lower risk of developing eczema.
- Irregular heartbeat (atrial fibrillation). Some research suggests that people who eat fish five or more times weekly have a reduced risk of irregular heartbeat. But most research suggests that eating fatty fish or taking fish oil supplements does not reduce the risk of irregular heartbeat.
- A lung disease that affects newborns (bronchopulmonary dysplasia). Giving fish oil by mouth to premature infants doesn’t appear to reduce the infant’s risk of developing this lung disease.
- Long-term blood flow problems in the brain (cerebrovascular diseases). Some early research suggests that eating fish reduces the risk of cerebrovascular disease. But higher quality research suggests that taking fish oil does not have this effect.
- Memory and thinking skills (cognitive function). Most research shows that taking fish oil supplements does not improve mental function in older people, young adults, or children.
- A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Taking fish oil by mouth does not seem to improve H. pylori infections when compared to standard medications.
- Kidney transplant. Research shows that taking fish oil doesn’t help people live longer after a kidney transplant. It also doesn’t seem to prevent the body from rejecting the transplant.
- Breast pain (mastalgia). Taking fish oil does not appear to reduce long-term breast pain.
- Migraine. Taking fish oil by mouth does not appear to decrease the number or severity of migraines.
- Multiple sclerosis (MS). Taking fish oil does not appear to improve the duration, frequency, or severity of relapses in patients with multiple sclerosis.
- Osteoarthritis. Most research shows that taking fish oil doesn’t improve pain or function in people with osteoarthritis. Also, adding fish oil to glucosamine doesn’t reduce pain or stiffness better than taking glucosamine alone.
- High blood pressure during pregnancy. Fish oil does not seem to prevent high blood pressure during pregnancy.
- A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Fish oil does not seem to prevent pre-eclampsia.
- Age-related muscle loss (sarcopenia). Despite some conflicting results, most research shows that taking fish oil supplements while participating in physical activity or strength training doesn’t improve muscle strength in older adults.
- Abnormal rapid heart rhythms (ventricular arrhythmias). Population research suggests that eating a lot of fish has no effect on the risk for abnormal rapid heart rhythms. Clinical research is inconsistent. Some research shows that taking fish oil daily does not affect the risk for abnormal heart rhythms. But other research shows that taking fish oil for 11 months delays the development of the condition. However, overall, taking fish oil does not seem to reduce the risk of death in people with abnormal rapid heart rhythms.
Probably Ineffective for …
- Diabetes. Taking fish oil doesn’t lower blood sugar in people with type 2 diabetes. It also doesn’t reduce the risk of certain complications of diabetes, such as heart attack and stroke. But taking fish oil might provide some other benefits for people with diabetes. For example, it may lower blood fats called triglycerides. In pregnant women, fish oil doesn’t reduce the risk of getting diabetes.
Insufficient Evidence to Make a Determination for …
- A sudden and serious lung condition (acute respiratory distress syndrome or ARDS). Early research shows that giving fish oil intravenously (by IV) might help lung function in people with a sudden and serious lung condition called ARDS.
- Decline in memory and thinking skills that occurs normally with age. Early research shows that taking fish oil does not help with the decline in memory and thinking skills that occurs with age.
- An eye disease that leads to vision loss in older adults (age-related macular degeneration or AMD). There is some evidence that people who eat fish more than once weekly have a reduced risk of developing age-related vision loss. But clinical research shows that taking fish oil by mouth for up to 5 years does not prevent vision loss.
- Hay fever. Early research suggests that mothers who take fish oil supplements during the late stages of pregnancy may lower the occurrence of allergies in their children. But other research suggests that fish oil does not reduce the development of allergies in children when taken by the mother during pregnancy.
- Alzheimer disease. There is some early evidence that fish oil might help prevent Alzheimer disease. However, it does not seem to help prevent a decline in thinking skills for most people who have already been diagnosed with Alzheimer disease.
- Miscarriage in pregnant women with an autoimmune disorder called antiphospholipid syndrome. Early research shows that taking fish oil by mouth might prevent miscarriages and increase live birth rates in pregnant women with this condition.
- Asthma. Some research suggests that fish oil supplements might help TREAT some asthma symptoms. But results aren’t consistent. Some research shows that taking fish oil improves breathing and reduces the need for medication. Other research shows that fish oil does not reduce the severity of asthma is children.
Fish oil might help PREVENT asthma in young children when taken by the mother while pregnant. But fish oil does not seem to provide any benefits when taken by the mother while breastfeeding or by the infant.
Overall, research suggests that fish oil does not help TREAT eczema once it has developed.
- Athletic performance. Some evidence suggests that taking fish oil can improve lung function in athletes. But other evidence suggests that taking fish oil does not improve endurance, recovery, heart rate, or exercise duration.
- Attention deficit-hyperactivity disorder (ADHD) in children. Early research shows that taking fish oil improves attention, mental function, and behavior in children 8-13 years-old with ADHD.
- Autism. One small study shows that taking fish oil might reduce hyperactivity in children with autism. But this study had flaws. Other research shows that taking fish oil doesn’t reduce hyperactivity.
- Bipolar disorder. Early research shows that taking fish oil along with conventional treatments for bipolar disorder may improve symptoms of depression, but not mania, in people with this condition.
- Cancer. Research on the effects of fish oil in preventing cancer has produced conflicting results. Some research linked eating fish or having higher blood levels of omega-3 fatty acids is a lower risk of different cancers. But other research suggests that eating fish does not reduce the risk of cancer.
- Heart disease. Most research shows that taking fish oil supplements doesn’t prevent heart disease or reduce the chance of heart-related events in people with heart disease. Getting fish oil from the diet might be beneficial. But benefits are probably modest at best. People should still eat fish and other foods that provide fish oil, though. These foods make up part of a healthy diet.
- Cataracts. There is some early evidence that eating fish three times weekly can slightly lower the risk of developing cataracts.
- Long-term kidney disease (chronic kidney disease or CKD). Early research shows that taking fish oil might reduce the chance of death from heart disease in people with CKD who are receiving hemodialysis. But it doesn’t seem to reduce the chance of death from other causes. It also doesn’t seem to help people who aren’t on hemodialysis.
- A lung disease that makes it harder to breathe (chronic obstructive pulmonary disease or COPD). Early research shows that taking fish oil doesn’t seem to improve lung problems in people with COPD.
- Liver scarring (cirrhosis). Early research shows that taking fish oil by mouth does not seem to improve kidney problems in people with cirrhosis.
- Decline in memory and thinking skills in older people that is more than what is normal for their age. Some research suggests that taking fish oil by mouth daily for 12 months might improve memory in people with reduced mental function. But not all research agrees.
- Colon cancer, rectal cancer. Some research shows that taking fish oil supplements doesn’t decrease a person’s risk of developing colon cancer. In people who already have colon cancer, some early research shows that taking fish oil during chemotherapy might slow the growth of tumors. But it doesn’t prevent death, hospitalizations, or other issues. Other early research suggests that fish oil in the diet or as a supplement doesn’t increase survival in people with stage three colon cancer.
- Surgery to improve blood flow to the heart (CABG surgery). Early research shows that taking fish oil seems to prevent grafts from re-closing after this surgery.
- A type of inflammatory bowel disease (Crohn disease). Research into the effects of fish oil on Crohn disease has produced conflicting results. Some research shows that taking a specific fish oil product can reduce the relapse of Crohn disease for people who have recovered. However, other research shows that fish oil does not have this effect.
- High blood pressure caused by the drug cyclosporine. Early research shows that taking fish oil seems to prevent high blood pressure caused by this drug.
- Cystic fibrosis. Early research suggests that taking fish oil by mouth can improve lung function in people with cystic fibrosis. However, administering fish oil intravenously (IV) does not have this effect.
- Diseases, such as Alzheimer disease, that interfere with thinking (dementia). Some early research suggests that eating fish at least once per week reduces the risk of developing dementia. Other research suggests there is no link between fish consumption and the risk of dementia.
- Depression. People who eat more fish seem to have a lower risk of depression. But it isn’t clear if taking fish oil supplements can reduce symptoms of depression. Some research shows that people with more severe depression might benefit. But people with mild depression or people with a medical condition that is causing their depression, might not. Also, it seems that only supplements that contain high amounts of eicosapentaenoic acid (EPA) actually work for depression.
- Kidney damage in people with diabetes (diabetic nephropathy). Evidence suggests that taking fish oil does not improve kidney function in people with type 1 diabetes who have this condition. In people with type 2 diabetes, some research shows that taking fish oil might help kidney function. But more research is needed.
- Vision problems in people with diabetes (diabetic retinopathy). Higher intake of fish oil from the diet has been linked to a reduced risk of eye damage in people with diabetes.
- Dry eye. Higher intake of fish oil from the diet has been linked to a lower risk of dry eye in women. But the effects of fish oil in people with dry eye are inconsistent. Some research shows that fish oil reduces dry eye symptoms such as pain, blurred vision, and sensitivity. But fish oil doesn’t seem to improve other signs and symptoms of dry eye such as tear production and damage to the surface of the eye. Taking fish oil also doesn’t improve signs and symptoms of dry eye when used with other dry eye treatments.
- A learning disorder marked by difficulty reading (dyslexia). Taking fish oil by mouth seems to improve night vision in children with dyslexia.
- Abnormal levels of cholesterol or blood fats (dyslipidemia). There is conflicting data about the effects of fish oil on blood fats in people with abnormal blood fat levels. Research shows that eating two servings of fish per week can lower cholesterol and blood fats in people with high cholesterol. Taking fish oil supplements also seems to improve levels of triglycerides and certain other blood fats in people with diabetes and in people with kidney transplants. But most research shows that taking fish oil supplements does not improve cholesterol levels in people with abnormal or high cholesterol levels. In fact, taking fish oil supplements might actually increase low-density lipoprotein (LDL or “bad”) cholesterol levels in these people.
- Cancer of the lining of the uterus (endometrial cancer). There is some evidence that women who regularly eat about two servings of fatty fish weekly have a lower risk of developing endometrial cancer.
- A painful uterine disorder (endometriosis). In adolescent girls that have gone through surgery for endometriosis, taking fish oil does not help to reduce pain. But it isn’t known if taking fish oil would help to reduce pain associated with endometriosis before going through surgery.
- Seizure disorder (epilepsy). Research suggests that taking omega-3 fatty acids from fish oil by mouth daily for 10 weeks reduces seizures in people with epilepsy that is resistant to drugs.
- Muscle soreness caused by exercise. Taking fish oil might lessen exercise-induced muscle soreness in professional athletes. But these early results need to be confirmed in larger, high quality studies. It’s unclear if fish oil reduces exercise-induced muscle soreness in untrained adults. Results from early research are conflicting.
- Food allergies. Taking fish oil during pregnancy seems to reduce the risk of egg allergies in the infant. But it doesn’t reduce the risk of other food allergies such as milk or peanut allergies in the infant.
- A mild form of gum disease (gingivitis). Early research shows that taking fish oil does not seem to improve gingivitis.
- Preventing blockage of grafts used in kidney dialysis. Taking fish oil seems to help prevent blood clot formation in hemodialysis grafts. It might also help the grafts work longer. But more research is needed to know which dose of fish oil is best.
- Complications after a heart transplant. Early research shows that taking fish oil might preserve kidney function and reduce the long-term rise in blood pressure after heart transplantation.
- HIV/AIDS. Some early research shows that eating food bars containing fish oil does not change the levels of CD4 cells in people with HIV.
- Prediabetes. Taking fish oil does not seem to improve blood sugar in people with prediabetes. But it might help prevent prediabetes from advancing to type 2 diabetes.
- Infant development. The strongest research shows that taking fish oil supplements during pregnancy or breastfeeding does not improve mental development of the infant. Feeding infants formula with fish oil appears to improve the infant’s vision but not mental development.
- Kidney failure. Some research shows that taking fish oil reduces markers of swelling (inflammation) in adults with kidney failure. Early research in children with kidney failure shows that taking fish oil supplements can improve the levels of certain fats in the blood.
- Conditions in a man that prevent him from getting a woman pregnant within a year of trying to conceive (male infertility). Early research suggests that taking fish oil supplements might help some men to produce more semen.
- Symptoms of menopause. Some research shows that taking fish oil doesn’t reduce hot flashes or insomnia, or improve quality of life in women with menopause. But other research disagrees. Also, taking fish oil might reduce night sweats from menopause.
- Obesity. Most research shows that taking fish oil does not improve weight loss in obese adults or in children. But eating fish as part of a reduced-calorie diet seems to help.
- Swelling (inflammation) and sores inside the mouth (oral mucositis). Taking fish oil seems to reduce the severity and pain of sores in the mouth from cancer drugs.
- Weak and brittle bones (osteoporosis). Early research suggests that taking fish oil slows the rate of bone loss and increases bone density at the thigh bone (femur) and spine in elderly people with osteoporosis. But taking fish oil doesn’t slow bone loss in older people with osteoarthritis in the knee.
- Swelling (inflammation) of the pancreas (pancreatitis). Evidence suggests that feeding intravenously (IV) with nutrition that has been fortified with fish oil reduces the number of days of kidney replacement therapy needed by people with severe inflammation of the pancreas.
- Narrowing of blood vessels that causes poor blood flow to the limbs (peripheral arterial disease). Some research shows that taking fish oil by mouth does not appear to improve walking distance in people with leg pain due to blood flow problems.
- A serious gum infection (periodontitis). Taking fish oil might help to preserve gum health after dental cleaning in people with this condition.
- An inherited disorder that increases levels of phenylalanine in the blood (phenylketonuria or PKU). Some evidence suggests that taking fish oil supplements improves motor skills, coordination, and vision in children with a rare genetic disorder called phenylketonuria.
- Pneumonia. Population research shows no relationship between fish consumption and the risk of developing pneumonia.
- A type of anxiety that often develops after a terrifying event (post-traumatic stress disorder or PTSD). Some early research shows that adding supplements containing omega-3 fatty acids from fish oil to psychoeducation does not provide any further benefits to people with PTSD. Also, giving fish oil as part of a nutrition plan to patients in the intensive care unit of the hospital does not seem to prevent PTSD after they have recovered.
- Depression after childbirth (postpartum depression). Some research shows that taking fish oil during pregnancy might prevent depression after childbirth. But it doesn’t seem to prevent or treat depression during pregnancy.
- Preterm labor. Taking fish oil or eating seafood during pregnancy might help prevent premature delivery. But not all research agrees.
- Growth and development in premature infants. Baby formula that has been fortified with fatty acids from fish oil and borage oil seems to improve growth and nervous system development in premature infants, especially boys.
- Bed sores (pressure ulcers). Early research shows that adding fish oil to a feeding tube or IV might slow the growth of bed sores in hospitalized adults. Other research shows that applying fish oil to the heels of hospitalized adults does not reduce the risk of getting a bed sore on the heel.
- Scaly, itchy skin (psoriasis). There is some evidence that administering fish oil intravenously (by IV) can decrease the severity of psoriasis symptoms. Also, applying fish oil to the skin might improve some symptoms of psoriasis. But taking fish oil by mouth does not seem to have any effect on psoriasis.
- Raynaud syndrome. Early research shows that taking fish oil can improve cold tolerance in some people with the usual form of Raynaud syndrome. But people with Raynaud syndrome that is caused by a condition called progressive systemic sclerosis do not seem to benefit from fish oil supplements.
- Infection of the airways. Drinking a beverage containing fish oil, vitamin D, and protein does not seem to reduce upper airway infection in athletes.
- Inability of the body to properly break down drugs called salicylates (salicylate intolerance). Some early research suggests that taking fish oil might improve symptoms of salicylate intolerance, such as asthma attacks and itching.
- Schizophrenia. Fish oil might improve symptoms such as aggression in people with schizophrenia. But not all research agrees.
- Blood infection (sepsis). Giving fish oil as part of a nutrition plan to patients with sepsis might reduce the need for mechanical breathing and shorten the stay in the intensive care unit of the hospital. But giving fish oil does not improve survival or reduce the risk of brain injury or delirium in people with sepsis.
- Sickle cell disease. Early research suggests that taking fish oil can reduce severe pain episodes in people with sickle cell disease.
- Stroke. Taking fish oil supplements doesn’t seem to prevent stroke. It isn’t clear if eating more fish oil in the diet can help prevent stroke. Eating fish once or twice weekly seems to lower the risk of having a stroke by as much as 27%. But eating very high amounts of fish (more than 46 grams of fish per day) seems to increase stroke risk. And eating fish does not lower stroke risk in people who are already taking aspirin for prevention. Regardless, the American Heart Association (AHA) recommends eating non-fried fish 1-2 times weekly in place of less healthy protein options.
- An autoimmune disease that causes widespread swelling (systemic lupus erythematosus or SLE). Some early studies suggest that fish oil helps improve symptoms of SLE, while other studies show no effect.
- A type of inflammatory bowel disease (ulcerative colitis). Research studies into the effects of fish oil for treating ulcerative colitis show conflicting results.
- A motor skill disorder marked by clumsiness (developmental coordination disorder or DCD).
- Other conditions.
More evidence is needed to rate fish oil for these uses.
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.
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. 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.
When applied to the skin: There isn’t enough reliable information to know if fish oil is safe or what the side effects might be.
When given by IV: 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.
Special Precautions & Warnings:
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. In adolescents, fish oil has been used safely in doses of up to about 2.2 grams daily for 12 weeks. But young children should not eat more than two ounces of fish per week. Fish oil is also POSSIBLY SAFE when given in the vein by a health care professional to infants who cannot take food by mouth. 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.
Birth control pills (Contraceptive drugs)
Interaction Rating=Moderate Be cautious with this combination.
Fish oils seem to help reduce some fat levels in the blood. These fats are called triglycerides. Birth control pills might decrease the effectiveness of fish oils by reducing these fat levels in the blood.Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.
Medications for high blood pressure (Antihypertensive drugs)
Interaction Rating=Moderate Be cautious with this combination.
Fish oils seem to decrease blood pressure. Taking fish oils 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)
Interaction Rating=Minor Be watchful with this combination.
Fish oils might slow blood clotting. Taking fish oils 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), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.
Orlistat (Xenical, Alli)
Interaction Rating=Moderate Be cautious with this combination.
Orlistat (Xenical, Alli) is used for weight loss. It prevents dietary fats from being absorbed from the gut. There is some concern that orlistat (Xenical, Alli) might also decrease absorption of fish oil when they are taken together. To avoid this potential interaction take orlistat (Xenical, Alli) and fish oil at least 2 hours apart.
Herbs and supplements that might slow blood clotting: High doses of fish oil have been thought to slow blood clotting. However, most research shows that fish oil does not increase bleeding. Until more is known, be watchful if combining with herbs and supplements that might slow blood clotting. These herbs include angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, red clover, turmeric, willow, and others.
Vitamin E: 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.
- For high levels of fats called triglycerides in the blood (hypertriglyceridemia): Doses of 1-15 grams of fish oil daily for up to 6 months have been used in research. But most experts recommend taking a dose of fish oil that provides about 3.5 grams of omega-3 fatty acids daily. This amount is provided in four 1-gram capsules of prescription-only fish oil products. These prescription-only products include Lovaza (formerly known as Omacor, GlaxoSmithKline), Omtryg (Trygg Pharma, Inc.), and Epanova (AstraZeneca Pharmaceuticals). You might need to take as many as 12 capsules daily of most non-prescription fish oil supplements to get the same amount of omega-3 fatty acids.
- For a procedure to open a blocked or narrowed blood vessel (angioplasty): 6 grams of fish oil daily starting one month before angioplasty and continuing for one months after, followed by 3 grams daily for 6 months thereafter has been used. Also, 15 grams of fish oil has been taken daily for 3 weeks before angioplasty and for 6 months thereafter.
- For involuntary weight loss in people who are very ill (cachexia or wasting syndrome): 30 mL of a specific fish oil product (ACO Omega-3, Pharmacia, Stockholm, Sweden) providing 4.9 grams of EPA and 3.2 grams of DHA daily for 4 weeks has been used. 7.5 grams of fish oil daily providing EPA 4.7 grams and DHA 2.8 grams has been used for about 6 weeks. In addition, two cans of a fish oil nutritional supplement containing 1.09 grams of EPA and 0.96 grams of DHA per can have been used daily for up to 7 weeks.
- For kidney damage caused by the drug cyclosporine: 12 grams of fish oil daily for 2 months has been used after liver transplant. Also, 6 grams of fish oil daily for up to 3 months after kidney transplant has been used.
- For menstrual cramps (dysmenorrhea): A daily dose of 1080 mg of EPA and 720 mg DHA along with 1.5 mg of vitamin E daily for 2 months has been used. Also, 500-2500 mg of fish oil has been used daily for 2-4 months.
- For heart failure: 600 to 4300 mg of omega-3 fatty acids daily for up to 12 months has been used. Also, 1 gram of fish oil daily for about 2.9 years has been used.
- For abnormal levels of blood fats in people with HIV/AIDS: Two capsules of a specific fish oil supplement (Omacor, Pronova BioPharma, Norway) containing 460 mg of EPA plus 380 mg of DHA twice daily for 12 weeks has been used.
- For high blood pressure: 4 to 15 grams of fish oil daily, taken in single or divided doses, for up to 36 weeks has been used. Also, 3-15 grams of omega-3 fatty acids daily for 4 weeks has been used.
- For a condition that slowly leads to kidney disease (IgA nephropathy): 1-12 grams of fish oil daily for 2-4 years has been used. Also, 3 grams of fish oil in combination with a drug called renin-angiotensin system blocker (RASB) daily for 6 months has been used.
- For build up of fat in the liver in people who drink little or no alcohol (nonalcoholic fatty liver disease or NAFLD): Omega-3 fatty acids such as fish oil in a dose of 2.7 grams daily for an average of 6 months have been used.
- For a mental disorder marked by hallucinations and delusion (psychosis): Fish oil capsules containing 700 mg of EPA and 480 mg of DHA mixed with tocopherols and other omega-3 fatty acids daily for 12 weeks has been used.
- For rheumatoid arthritis (RA): 10 grams of fish oil daily for 6 months, or fish oil containing 0.5-4.6 grams of EPA and 0.2-3.0 grams of DHA, sometimes along with vitamin E 15 IU, daily for up to 15 months has been used.
- For rheumatoid arthritis (RA): 0.1-0.2 mg/kg of omega-3 fatty acids from fish oil daily for 7 days has been used. Also, 0.2 grams/kg of a specific fish oil solution (Omegaven, Fresenius-Kabi) daily for 14 consecutive days, followed by 0.05 grams of fish oil by mouth daily for 20 weeks, have been used.
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