Supplements Dietary Supplements Side Effects of Fish Oil Supplements By Jennifer Moll, PharmD Jennifer Moll, PharmD Facebook Jennifer Moll, MS, PharmD, is a pharmacist actively involved in educating patients about the importance of heart disease prevention. Learn about our editorial process Updated on June 03, 2022 Medically reviewed by Melissa Nieves, LND, RD Medically reviewed by Melissa Nieves, LND, RD Facebook LinkedIn Melissa Nieves, LND, RD, is a registered dietitian and licensed nutritionist who works as a bilingual telehealth dietitian. She founded the Fad Free Nutrition Blog and Nutricion al Grano websites and is based in Texas. Learn about our Medical Expert Board Print Verywell / Anastasia Tretiak Omega-3 fatty acids are a type of polyunsaturated fat found in high concentrations in certain fish, vegetables, nuts, and seeds. These include eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA), each of which is known to offer a variety of health benefits. Omega-3 fatty acids seem particularly useful in preventing atherosclerosis and heart disease. Studies have shown that consuming between 2 grams and 4 grams of omega-3 fatty acids per day can lower your triglyceride levels by anywhere between 20% and 45%. Sources The American Heart Association (AHA) recommends consuming obtaining omega-3 fats from foods. This includes: Fatty fish: The AHA suggests consuming two servings of fatty fish (such as salmon, anchovy, herring, and tuna) per week.Nuts: A small handful of walnuts, pecans, or almonds can have a positive impact on your lipid profile.Seeds: Chia and flax are rich sources of omega-3s. However, if you don't like fatty fish, nuts, or seeds, you can try fish oil supplements instead. They readily available over the counter in softgel capsule form. Plant Sources of Omega-3 Fatty Acids Possible Side Effects Although fish oil may seem like an easy way to improve your heart health, there are side effects associated with its use These appear to be dose-dependent, meaning that the higher dose you take, the more likely you will be to experience side effects. The most common side effects include: NauseaDiarrheaHeartburnAbdominal painBelching a fish-like aftertaste Taking high doses of omega-3 fats, including those found in fish oil supplements, may interact with certain medications. This especially holds true if you take anti-platelet drugs like Plavix (clopidogrel) or anticoagulants like Coumadin (warfarin). Taking these drugs with high-dose omega-3 supplements can increase the risk of bleeding or easy bruising. Additionally, high doses of omega-3s found in fish oil may slightly increase your blood sugar levels. In most cases, the effect won't interfere with diabetes medication or increase your risk of diabetes. Still, if you are struggling to manage your blood sugar, fish oil may not be the best option for you. You should avoid taking fish oil supplements at least a week before scheduled surgery (including dental surgery) to prevent excessive bleeding. To avoid interaction, always advise your healthcare provider about any medications you are taking, whether they are prescription, over-the-counter, dietary, herbal, or recreational. OTC vs. Prescription-Strength Omega-3 Supplements Verywell / Anastasia Tretiak Overdose People with heart disease are often advised to take 1 gram (1,000 milligrams) of a combination of DHA and EPA from fish oil each day. As beneficial as fish oil may be, It is possible to overdose on omega-3 fatty acids, triggering an array of adverse events, including: Bleeding gums Nosebleeds Hyperglycemia (high blood sugar) Hypotension (low blood pressure) Diarrhea Acid reflux Insomnia Doses of omega-3 fatty acids greater than 3 grams (3,000 milligrams) may increase your risk of bleeding, even if you are not taking blood-thinning medications. There is also concern that the high intake of omega-3 fatty acids could slow blood clotting to such a degree as to increase the risk of hemorrhagic stroke. People at risk of stroke should only use fish oil under the supervision of a cardiologist. Because fish oil contains high amounts of vitamin A, it is possible to develop vitamin A toxicity by taking too much. Symptoms include dizziness, nausea, joint pain, and skin irritation. Is Fish or Fish Oil Better for My Heath? Correction - February 2, 2023: This article was updated to clarify that high blood sugar is hyperglycemia. 8 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. 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 Jul 18;7(7):CD003177. doi:10.1002/14651858.CD003177.pub3 Office of Dietary Supplements. Omega-3 fatty acids: fact sheet for health professionals. American Heart Association. Fish and omega-3 fatty acids. Novotny K, Fritz K, Parmar M. Omega-3 fatty acids. In: StatPearls [Internet]. 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 Akintoye E, Sethi P, Harris WS, et al. Fish oil and peri-operative bleeding: insights from the Omega-3 Fatty Acids for Prevention of Postoperative Atrial Fibrillation (OPERA) Randomized Trial. Circ Cardiovasc Qual Outcomes. 2018 Nov;11(11):e004584. doi:10.1161/CIRCOUTCOMES.118.004584 Hamazaki T, Colleran H, Hamazaki K, Matsuoka Y, Itomura M, Hibbein J. The safety of fish oils for those whose risk of injury is high. Military Med. 2014:179(11):134. doi:10.7205/MILMED-D-14-00157 Olson JM, Ameer MA, Goyal A. Vitamin A toxicity. In: StatPearls [Internet]. By Jennifer Moll, PharmD Jennifer Moll, MS, PharmD, is a pharmacist actively involved in educating patients about the importance of heart disease prevention. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit