Fish oil

Is fish oil safe?

Updated 4 Nov 2026

Short answer

For most adults, yes, at the doses studied. EFSA found no safety concern for adults at up to 5 g of EPA and DHA a day.[1] LiverTox rates omega-3 fats as an unlikely cause of liver injury.[2]

Side effects are usually mild: unpleasant taste, bad breath, heartburn, nausea, stomach discomfort, diarrhea, headache and smelly sweat.[3]

Two risks grow with the dose. In people at high heart risk, more than 1.5 g a day raised the chance of atrial fibrillation, an irregular heartbeat.[4] High doses of purified EPA raised bleeding by 0.6 percentage points, while omega-3 fats overall did not raise it.[5]

People who take a blood thinner, have a heart condition, are pregnant or use cod liver oil should ask a doctor or pharmacist first.[3][6]

Sources (6)

  1. Scientific Opinion on the Tolerable Upper Intake Level of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). European Food Safety Authority, 2012. efsa.onlinelibrary.wiley.com
  2. Omega-3 Fatty Acids. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, 2017. PMID 31644217
  3. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  4. Effects of Omega-3 Fatty Acid Treatment on Risk for Atrial Fibrillation: An Updated Meta-Analysis of 35 Trials including 114 592 Individuals. Abuknesha NR, O'Keefe JH, Qian F, Tintle NL, Lin Y, Sun Y, et al. Circ Arrhythm Electrophysiol, 2026. PMID 42517224
  5. Bleeding Risk in Patients Receiving Omega-3 Polyunsaturated Fatty Acids: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Javaid M, Kadhim K, Bawamia B, Cartlidge T, Farag M, Alkhalil M J Am Heart Assoc, 2024. PMID 38742535
  6. Omega-3 Supplements: What You Need To Know. NIH National Center for Complementary and Integrative Health, 2024. www.nccih.nih.gov

More about fish oil

What is fish oil?Does fish oil reduce inflammation?How much EPA and DHA is in a fish oil capsule?Is eating fish better than taking fish oil?What is fish oil used for?Should fish oil be taken with food?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.