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.
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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.
ADULTS BY MOUTH: For high triglycerides: 1-15 grams of fish oil daily for up to 6 months, or fish oil providing 1.45 to 2.70 grams of EPA and 1.05 to 1.80 grams of DHA daily for 2 to 12 weeks, has been used. For heart disease: Fish oil containing 0.6-10 grams of DHA and/or EPA daily has been taken for one month to 9 years. For preventing and reversing the progression of hardening of the arteries after 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 preventing miscarriage in women with antiphospholipid antibody syndrome and a history of past miscarriage: 5.1 grams of fish oil with a 1.5 EPA:DHA ratio taken daily for 3 years has been used. For attention deficit-hyperactivity disorder (ADHD): A specific supplement containing 400 mg of fish oil and 100 mg of evening primrose oil (Eye Q, Novasel) six capsules daily for 15 weeks has been used. Also, 250 mg of a omega-3 fatty acids that have been complexed with phosphatidylserine have been used daily for 3 months. For bipolar disorder: Fish oil providing 6.2 grams of EPA and 3.4 grams of DHA taken daily for 4 months has been used. Also, 1-6 grams of EPA for 12-16 weeks or omega-3 fatty acids containing 4.4-6.2 grams of EPA plus 2.4-3.4 grams of DHA for 4-16 weeks have been used. For slowing weight loss in patients with cancer: 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 keeping veins open after coronary bypass surgery: 4 grams of fish oil containing 2.04 grams of EPA and 1.3 grams of DHA has been used daily for one year. For high blood pressure caused by the drug cyclosporine: 3 to 4 grams of omega-3 fatty acids daily for 6 months after a heart transplant has been used. 2-18 grams of fish oil daily for 1 to 12 months after a kidney transplant has also been used. For kidney problems related to using cyclosporine to prevent organ transplant rejection: 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 painful menstrual periods: 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. Heart transplant: 4 grams of fish oil containing 46.5% EPA and 37.8% of DHA daily for one year has been used. For abnormal cholesterol caused by HIV/AIDS treatment: 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 preserving kidney function in patients with severe 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 weak bones (osteoporosis): Four 500 mg capsules of a mixture of evening primrose and fish oil, taken three times daily with meals along with 600 mg of calcium carbonate for 18 months, has been used. For psoriasis: Fish oil capsules containing 3.6 grams of EPA and 2.4 grams of DHA daily for 15 weeks along with UVB therapy have been used. For 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 Raynaud's syndrome: A daily dose of 3.96 grams of EPA and 2.64 grams of DHA for 12 weeks has been used. For abnormal cholesterol levels following a kidney transplant: 6 grams of fish oil daily for 3 months 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. BY IV: For psoriasis: 100-200 mL of a specific fish oil solution containing 2.1 to 4.2 grams of EPA and 2.1 to 4.2 grams of DHA (Omegavenous, Fresenius, Oberursel, Germany), given daily for 10 to 14 days, 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. APPLIED TO THE SKIN: For psoriasis: Applying fish oil under a dressing for 6 hours daily for 4 weeks has been used. CHILDREN BY MOUTH: For developmental coordination disorder in children: Fish oil providing 558 mg of EPA and 174 mg of DHA in three divided doses daily for 3 months has been used in children aged 5-12 years. For improving movement disorders in children with poor coordination (dyspraxia): A specific supplement containing fish oil in combination with evening primrose oil, thyme oil, and vitamin E (Efalex, Efamol Ltd), taken daily for 4 months, has been used.