Fish Oil Burps, Aftertaste and Enteric Coatings: Why It Happens and What Is Known
What health bodies, prescribing labels and trials say about fish oil burps and aftertaste, what enteric coatings were tested for, and where proper evidence on fixes was not found.
Content last updated . This page has not been medically reviewed.
Quick answer
Fishy burps and an unpleasant taste are among the side effects listed for omega-3 supplements. The NCCIH says side effects are usually mild and include unpleasant taste, bad breath, bad-smelling sweat, headache, and gastrointestinal symptoms such as heartburn, nausea and diarrhea. [1] We found no study that tested whether enteric coatings, capsule types or timing reduce burps in fish oil supplements. Evidence labels: mixed, insufficient evidence, Proper evidence not found (searched PubMed for fish oil eructation, burp, aftertaste and enteric-coated omega-3 tolerability; no direct comparison came up).
What the sources found
| Source | What it reports |
|---|---|
| Meta-analysis of 21 trials of prescription omega-3 products, 24,460 participants [2] | More fishy taste than control; EPA and DHA combination products had more belching and nausea; no definite serious adverse events |
| US prescribing information for a prescription ethyl ester product [3] | Most common adverse reactions (over 3% and more than placebo) were eructation, dyspepsia and taste perversion |
| Single-dose crossover trial, 22 adults [4] | Ethyl ester, triglyceride and monoglyceride forms had similar eructation, dysgeusia, abdominal discomfort, nausea and bloating |
These involve prescription-strength products or single doses. Over-the-counter oils may differ. Evidence label: insufficient evidence for claims that one form or brand type causes fewer burps.
What "enteric-coated" was tested for
An enteric coating is designed to protect a capsule from stomach acid. In a one-year trial of 78 people with Crohn's disease in remission, an enteric-coated fish oil protected capsules from gastric acidity for at least 30 minutes; the authors noted fish oil is often poorly tolerated because of taste and gastrointestinal side effects. [5] Four people on fish oil and one on placebo dropped out because of diarrhea. [5] The trial measured relapse, not burps, and did not compare coated with uncoated capsules. A small uncontrolled study of a gastro-resistant free fatty acid EPA capsule in 35 people (10 with ulcerative colitis, 10 with Crohn's disease, 15 healthy) reported it was well tolerated. [6] Neither study shows that coating prevents burps in general. Do not transfer these results to other products or conditions.Common ideas that we could not check
Advice such as taking capsules with meals, choosing smaller capsules or freezing them is common. In the sources we read, none tested these for burps: Proper evidence not found. Rancid oil may taste worse; one stability study found that aroma and taste generally changed in a negative way during storage. [7] That study did not measure burping. See Oxidation and rancidity and Storing omega-3 supplements.When to ask a clinician
Persistent heartburn, vomiting or diarrhea, or any side effect that worries you deserves a conversation with a clinician or pharmacist, especially if you take other medicines. If you think you are having an allergic reaction, seek urgent medical help (in the US, call 911); prescribing information for a prescription product says to seek medical attention if reactions occur. [8] Fish oil may also affect bleeding and interact with medicines, so tell the surgical team before an operation. See Omega-3 safety and interactions and the side effects quick reference.Related
Oil source and form: Fish oil, Fish oil vs algal oil, How to read a fish oil label.Frequently asked questions
Why does fish oil make me burp?
The sources we read describe burping as a common reported effect but do not test the cause. [1][2]
Do enteric-coated capsules stop fish burps?
Proper evidence not found. Enteric coatings were studied for other aims. [5]
Is a fishy aftertaste a sign the oil is rancid?
Not necessarily. Fishy taste was also reported more often with prescription products than control. [2]
Are triglyceride forms gentler?
One single-dose trial found similar side effects across forms. [4]
Is burping a sign of a problem?
Usually mild per the NCCIH, but ask a clinician if it persists or comes with other symptoms. [1]
References
- NCCIH, Omega-3 Supplements: What You Need To Know. Read 2026-10-22.
- Chang CH et al. Safety and tolerability of prescription omega-3 fatty acids: a systematic review and meta-analysis of randomized controlled trials. Prostaglandins Leukot Essent Fatty Acids 2018. Read 2026-10-22.
- FDA-approved prescribing information, omega-3-acid ethyl esters prescription capsules, DailyMed, revised 11/2024. Read 2026-10-22.
- Chevalier L, Vachon A, Plourde M. Pharmacokinetics of supplemental omega-3 fatty acids esterified in monoglycerides, ethyl esters, or triglycerides in adults in a randomized crossover trial. J Nutr 2021. Read 2026-10-22.
- Belluzzi A et al. Effect of an enteric-coated fish-oil preparation on relapses in Crohn's disease. N Engl J Med 1996. Read 2026-10-22.
- Scaioli E et al. The pharmacokinetic profile of a new gastroresistant capsule preparation of eicosapentaenoic acid as the free fatty acid. Biomed Res Int 2015. Read 2026-10-22.
- Yenipazar H, Sahin-Yesilcubuk N. Effect of packaging and encapsulation on the oxidative and sensory stability of omega-3 supplements. Food Sci Nutr 2023 (full text). Read 2026-10-22.
- FDA-approved prescribing information, icosapent ethyl prescription capsules, DailyMed, revised 3/2026. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.