Does Fish Oil Have Side Effects?

Table of ContentsView AllTable of ContentsCommon Side EffectsLess Common but Serious Side EffectsFactors Influencing Side EffectsPrecautionsEating Fish as a Safe Alternative

Table of ContentsView All

View All

Table of Contents

Common Side Effects

Less Common but Serious Side Effects

Factors Influencing Side Effects

Precautions

Eating Fish as a Safe Alternative

Fish oil is one of the most commonly used supplements. It is a potent source of omega-3 fatty acids, nutrients associated with many anti-inflammatory, health-promoting benefits.

Specifically, fish oil containsdocosahexaenoicacid (DHA) andeicosapentaenoicacid (EPA), two omega-3 fatty acids with health benefits, including supporting a healthy heart and brain.

However, like all supplements and medications, fish oil supplements can produce side effects.

Although generally safe, fish oil supplements can have side effects, some of which may impact your health. Some side effects may depend on the dosage of fish oil, with more intense effects at higher doses.

Common, more mild side effects of fish oil supplements include the following:

Other side effects include the following:

Fish oil supplements may cause more severe side effects in some individuals, including the following:

Several factors influence side effect risk from fish oil, primarily specific pre-existing heart conditions and how much fish oil you take (dosage).

The U.S. Food and Drug Administration (FDA) deems 5 g daily of omega-3 supplements, likefish oil, safe for most people.However, specific doses of fish oil may contribute to more or worse side effects and may differ if you live with specific types of heart disease.

For example, the risk of A-fib associated with fish oil may be dose-dependent, with higher doses increasing risk.Some research suggests daily dosages of over 4 g may increase the risk of A-fib in people with specific heart conditions or at high risk of A-fib.

Also, consuming over 3 g of fish oil a day may increase the risk of excessive bleeding.

Keep in mind that while higher doses may be harmful to some people, they may benefit others.

Specific populations may need to use additional caution when considering fish oil.

You should also avoid fish oil if you’re allergic to it or its components (parts).

Your healthcare provider may suggest that you stop taking fish oil supplements before surgery due to their potential blood thinning effects. Interestingly, though, recent research contradicts this long-standing recommendation.

Fish oil andfish liver oilare two different types of supplements. Although both are significant sources of omega-3s, fish liver oil naturally containsvitamins AandD. High doses of either can betoxic. Additionally, taking high doses of vitamin A from fish liver oil or other sources when trying to get pregnant or during pregnancy can harm your fetus.

DHA and EPA are recommended during pregnancy to support fetal brain development and reduce the risk of preterm birth.Taking regular fish oil supplements and avoiding fish liver oil may be asafer alternative.

Check with your healthcare provider for additional guidance.

Drug Interactions

Fish oil may interact with the following medications:

Consult your pharmacist or healthcare provider for more information about fish oil interactions.

As long as you are not allergic, eating fish is a safe and effective way to consume omega-3 fatty acids. Unlike fish oil supplements, there are minimal safety concerns when eating fish.

Goodsources of omega-3-rich fish include salmon,sardines, mackerel, and anchovies.Aside from omega-3s,fishprovide other essential nutrients like selenium, iodine, and zinc. Regular fish oil supplements may lack these additional vital nutrients.

Avoid consuming mercury-heavy fish like king mackerel, shark, tilefish, and swordfish.

Summary

Fish oil is among the most commonly used supplements for its purported health benefits, namely its effects on heart health.

Its side effects range from gastrointestinal issues to more severe effects like delayed blood clotting and reduced immune function. However, for most individuals, the side effects of fish oil supplements are minimal.

So, any benefit may outweigh the risks associated with fish oil supplements.Still, always consult a healthcare provider before picking a newfish oil supplementto ensure it is safe and effective for you.

17 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institutes of Health Office of Dietary Supplements.Omega-3 fatty acids.Chang JPC, Tseng PT, Zeng BS, et al.Safety of supplementation of omega-3 polyunsaturated fatty acids: a systematic review and meta-analysis of randomized controlled trials.Adv Nutr. 2023;14(6):1326-1336. doi:10.1016/j.advnut.2023.08.003National Center for Complementary and Integrative Health.Omega-3 supplements: in depth.Wang HF, Liu WC, Zailani H, et al.A 12-week randomized double-blind clinical trial of eicosapentaenoic acid intervention in episodic migraine.Brain Behav Immun. 2024;118:459-467. doi:10.1016/j.bbi.2024.03.019Chen C, Yu X, Shao S.Effects of omega-3 fatty acid supplementation on glucose control and lipid levels in type 2 diabetes: a meta-analysis.PLoS One. 2015;10(10):e0139565. doi:10.1371/journal.pone.0139565Gao H, Geng T, Huang T, et al.Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis.Lipids Health Dis. 2017;16(1):131. doi:10.1186/s12944-017-0528-0Zhang X, Ritonja JA, Zhou N, et al.Omega-3 polyunsaturated fatty acids intake and blood pressure: a dose-response meta-analysis of randomized controlled trials.J Am Heart Assoc. 2022;11(11):e025071. doi:10.1161/JAHA.121.025071Wang J, Gaman MA, Albadawi NI, et al.Does omega-3 fatty acid supplementation have favorable effects on the lipid profile in postmenopausal women? A systematic review and dose-response meta-analysis of randomized controlled trials.Clin Ther. 2023;45(1):e74-e87. doi:10.1016/j.clinthera.2022.12.009Oelrich B, Dewell A, Gardner CD.Effect of fish oil supplementation on serum triglycerides, LDL cholesterol and LDL subfractions in hypertriglyceridemic adults.Nutr Metab Cardiovasc Dis. 2013;23(4):350-357. doi:10.1016/j.numecd.2011.06.003Chen G, Qian ZM, Zhang J, et al.Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study.BMJ Med. 2024;3(1):e000451. doi:10.1136/bmjmed-2022-000451U.S. Food and Drug Administration.Qualified health claims: Letters of enforcement discretion.Abdelhamid AS, Brown TJ, Brainard JS, et al.Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.Cochrane Database Syst Rev. 2018;11(11):CD003177. doi:10.1002/14651858.CD003177.pub4Akintoye E, Sethi P, Harris WS, et al.Fish oil and perioperative bleeding: insights from the OPERA randomized trial.Circ Cardiovasc Qual Outcomes. 2018;11(11):e004584. doi:10.1161/CIRCOUTCOMES.118.004584National Center for Complementary and Integrative Health.5 things to know about omega-3s for heart disease.Cetin I, Carlson SE, Burden C, et al.Omega-3 fatty acid supply in pregnancy for risk reduction of preterm and early preterm birth.Am J Obstet Gynecol MFM. 2024;6(2):101251. doi:10.1016/j.ajogmf.2023.101251U.S. Food and Drug Administration.Advice about eating fish.Siscovick DS, Barringer TA, Fretts AM, et al.Omega-3 polyunsaturated fatty acid (fish oil) supplementation and the prevention of clinical cardiovascular disease: a science advisory from the American Heart Association.Circulation. 2017;135(15):e867-e884. doi:10.1161/CIR.0000000000000482

17 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institutes of Health Office of Dietary Supplements.Omega-3 fatty acids.Chang JPC, Tseng PT, Zeng BS, et al.Safety of supplementation of omega-3 polyunsaturated fatty acids: a systematic review and meta-analysis of randomized controlled trials.Adv Nutr. 2023;14(6):1326-1336. doi:10.1016/j.advnut.2023.08.003National Center for Complementary and Integrative Health.Omega-3 supplements: in depth.Wang HF, Liu WC, Zailani H, et al.A 12-week randomized double-blind clinical trial of eicosapentaenoic acid intervention in episodic migraine.Brain Behav Immun. 2024;118:459-467. doi:10.1016/j.bbi.2024.03.019Chen C, Yu X, Shao S.Effects of omega-3 fatty acid supplementation on glucose control and lipid levels in type 2 diabetes: a meta-analysis.PLoS One. 2015;10(10):e0139565. doi:10.1371/journal.pone.0139565Gao H, Geng T, Huang T, et al.Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis.Lipids Health Dis. 2017;16(1):131. doi:10.1186/s12944-017-0528-0Zhang X, Ritonja JA, Zhou N, et al.Omega-3 polyunsaturated fatty acids intake and blood pressure: a dose-response meta-analysis of randomized controlled trials.J Am Heart Assoc. 2022;11(11):e025071. doi:10.1161/JAHA.121.025071Wang J, Gaman MA, Albadawi NI, et al.Does omega-3 fatty acid supplementation have favorable effects on the lipid profile in postmenopausal women? A systematic review and dose-response meta-analysis of randomized controlled trials.Clin Ther. 2023;45(1):e74-e87. doi:10.1016/j.clinthera.2022.12.009Oelrich B, Dewell A, Gardner CD.Effect of fish oil supplementation on serum triglycerides, LDL cholesterol and LDL subfractions in hypertriglyceridemic adults.Nutr Metab Cardiovasc Dis. 2013;23(4):350-357. doi:10.1016/j.numecd.2011.06.003Chen G, Qian ZM, Zhang J, et al.Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study.BMJ Med. 2024;3(1):e000451. doi:10.1136/bmjmed-2022-000451U.S. Food and Drug Administration.Qualified health claims: Letters of enforcement discretion.Abdelhamid AS, Brown TJ, Brainard JS, et al.Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.Cochrane Database Syst Rev. 2018;11(11):CD003177. doi:10.1002/14651858.CD003177.pub4Akintoye E, Sethi P, Harris WS, et al.Fish oil and perioperative bleeding: insights from the OPERA randomized trial.Circ Cardiovasc Qual Outcomes. 2018;11(11):e004584. doi:10.1161/CIRCOUTCOMES.118.004584National Center for Complementary and Integrative Health.5 things to know about omega-3s for heart disease.Cetin I, Carlson SE, Burden C, et al.Omega-3 fatty acid supply in pregnancy for risk reduction of preterm and early preterm birth.Am J Obstet Gynecol MFM. 2024;6(2):101251. doi:10.1016/j.ajogmf.2023.101251U.S. Food and Drug Administration.Advice about eating fish.Siscovick DS, Barringer TA, Fretts AM, et al.Omega-3 polyunsaturated fatty acid (fish oil) supplementation and the prevention of clinical cardiovascular disease: a science advisory from the American Heart Association.Circulation. 2017;135(15):e867-e884. doi:10.1161/CIR.0000000000000482

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Institutes of Health Office of Dietary Supplements.Omega-3 fatty acids.Chang JPC, Tseng PT, Zeng BS, et al.Safety of supplementation of omega-3 polyunsaturated fatty acids: a systematic review and meta-analysis of randomized controlled trials.Adv Nutr. 2023;14(6):1326-1336. doi:10.1016/j.advnut.2023.08.003National Center for Complementary and Integrative Health.Omega-3 supplements: in depth.Wang HF, Liu WC, Zailani H, et al.A 12-week randomized double-blind clinical trial of eicosapentaenoic acid intervention in episodic migraine.Brain Behav Immun. 2024;118:459-467. doi:10.1016/j.bbi.2024.03.019Chen C, Yu X, Shao S.Effects of omega-3 fatty acid supplementation on glucose control and lipid levels in type 2 diabetes: a meta-analysis.PLoS One. 2015;10(10):e0139565. doi:10.1371/journal.pone.0139565Gao H, Geng T, Huang T, et al.Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis.Lipids Health Dis. 2017;16(1):131. doi:10.1186/s12944-017-0528-0Zhang X, Ritonja JA, Zhou N, et al.Omega-3 polyunsaturated fatty acids intake and blood pressure: a dose-response meta-analysis of randomized controlled trials.J Am Heart Assoc. 2022;11(11):e025071. doi:10.1161/JAHA.121.025071Wang J, Gaman MA, Albadawi NI, et al.Does omega-3 fatty acid supplementation have favorable effects on the lipid profile in postmenopausal women? A systematic review and dose-response meta-analysis of randomized controlled trials.Clin Ther. 2023;45(1):e74-e87. doi:10.1016/j.clinthera.2022.12.009Oelrich B, Dewell A, Gardner CD.Effect of fish oil supplementation on serum triglycerides, LDL cholesterol and LDL subfractions in hypertriglyceridemic adults.Nutr Metab Cardiovasc Dis. 2013;23(4):350-357. doi:10.1016/j.numecd.2011.06.003Chen G, Qian ZM, Zhang J, et al.Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study.BMJ Med. 2024;3(1):e000451. doi:10.1136/bmjmed-2022-000451U.S. Food and Drug Administration.Qualified health claims: Letters of enforcement discretion.Abdelhamid AS, Brown TJ, Brainard JS, et al.Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.Cochrane Database Syst Rev. 2018;11(11):CD003177. doi:10.1002/14651858.CD003177.pub4Akintoye E, Sethi P, Harris WS, et al.Fish oil and perioperative bleeding: insights from the OPERA randomized trial.Circ Cardiovasc Qual Outcomes. 2018;11(11):e004584. doi:10.1161/CIRCOUTCOMES.118.004584National Center for Complementary and Integrative Health.5 things to know about omega-3s for heart disease.Cetin I, Carlson SE, Burden C, et al.Omega-3 fatty acid supply in pregnancy for risk reduction of preterm and early preterm birth.Am J Obstet Gynecol MFM. 2024;6(2):101251. doi:10.1016/j.ajogmf.2023.101251U.S. Food and Drug Administration.Advice about eating fish.Siscovick DS, Barringer TA, Fretts AM, et al.Omega-3 polyunsaturated fatty acid (fish oil) supplementation and the prevention of clinical cardiovascular disease: a science advisory from the American Heart Association.Circulation. 2017;135(15):e867-e884. doi:10.1161/CIR.0000000000000482

National Institutes of Health Office of Dietary Supplements.Omega-3 fatty acids.

Chang JPC, Tseng PT, Zeng BS, et al.Safety of supplementation of omega-3 polyunsaturated fatty acids: a systematic review and meta-analysis of randomized controlled trials.Adv Nutr. 2023;14(6):1326-1336. doi:10.1016/j.advnut.2023.08.003

National Center for Complementary and Integrative Health.Omega-3 supplements: in depth.

Wang HF, Liu WC, Zailani H, et al.A 12-week randomized double-blind clinical trial of eicosapentaenoic acid intervention in episodic migraine.Brain Behav Immun. 2024;118:459-467. doi:10.1016/j.bbi.2024.03.019

Chen C, Yu X, Shao S.Effects of omega-3 fatty acid supplementation on glucose control and lipid levels in type 2 diabetes: a meta-analysis.PLoS One. 2015;10(10):e0139565. doi:10.1371/journal.pone.0139565

Gao H, Geng T, Huang T, et al.Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis.Lipids Health Dis. 2017;16(1):131. doi:10.1186/s12944-017-0528-0

Zhang X, Ritonja JA, Zhou N, et al.Omega-3 polyunsaturated fatty acids intake and blood pressure: a dose-response meta-analysis of randomized controlled trials.J Am Heart Assoc. 2022;11(11):e025071. doi:10.1161/JAHA.121.025071

Wang J, Gaman MA, Albadawi NI, et al.Does omega-3 fatty acid supplementation have favorable effects on the lipid profile in postmenopausal women? A systematic review and dose-response meta-analysis of randomized controlled trials.Clin Ther. 2023;45(1):e74-e87. doi:10.1016/j.clinthera.2022.12.009

Oelrich B, Dewell A, Gardner CD.Effect of fish oil supplementation on serum triglycerides, LDL cholesterol and LDL subfractions in hypertriglyceridemic adults.Nutr Metab Cardiovasc Dis. 2013;23(4):350-357. doi:10.1016/j.numecd.2011.06.003

Chen G, Qian ZM, Zhang J, et al.Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study.BMJ Med. 2024;3(1):e000451. doi:10.1136/bmjmed-2022-000451

U.S. Food and Drug Administration.Qualified health claims: Letters of enforcement discretion.

Abdelhamid AS, Brown TJ, Brainard JS, et al.Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease.Cochrane Database Syst Rev. 2018;11(11):CD003177. doi:10.1002/14651858.CD003177.pub4

Akintoye E, Sethi P, Harris WS, et al.Fish oil and perioperative bleeding: insights from the OPERA randomized trial.Circ Cardiovasc Qual Outcomes. 2018;11(11):e004584. doi:10.1161/CIRCOUTCOMES.118.004584

National Center for Complementary and Integrative Health.5 things to know about omega-3s for heart disease.

Cetin I, Carlson SE, Burden C, et al.Omega-3 fatty acid supply in pregnancy for risk reduction of preterm and early preterm birth.Am J Obstet Gynecol MFM. 2024;6(2):101251. doi:10.1016/j.ajogmf.2023.101251

U.S. Food and Drug Administration.Advice about eating fish.

Siscovick DS, Barringer TA, Fretts AM, et al.Omega-3 polyunsaturated fatty acid (fish oil) supplementation and the prevention of clinical cardiovascular disease: a science advisory from the American Heart Association.Circulation. 2017;135(15):e867-e884. doi:10.1161/CIR.0000000000000482

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