How to Choose an Omega-3 Supplement

Omega-3 supplements can look alike on a results page, yet the labels differ in ways that matter: how much EPA and DHA a serving supplies, what the oil comes from, whether anyone outside the company has checked the batch, and what the packaging promises. This guide sets out what to check before you buy, for healthy adults. If you are pregnant, buying for a child, take a blood thinner, have a fish or shellfish allergy or have been prescribed an omega-3 medicine, read the cautions near the end first.

The criteria come from named public sources: the Food and Drug Administration (FDA), the National Center for Complementary and Integrative Health (NCCIH), the Dietary Guidelines for Americans, the American Heart Association (AHA) and the Linus Pauling Institute at Oregon State University. We do not rank products or rate brands. Amazon links on this page open searches built from the criteria, and you check each listing against its label.

First, ask whether food already covers it

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the long-chain omega-3 fats found in seafood. NCCIH reports that the 2020-2025 Dietary Guidelines advise adults to eat 8 ounces or more of a variety of seafood a week, and the AHA recommends two 3-ounce servings of fish a week, particularly fatty fish. The 2025-2030 guidelines, issued in January 2026, list omega-3-rich seafood among healthy-fat foods, and the report behind them puts average American intake of EPA and DHA at about 110 milligrams a day. NCCIH adds that for some conditions the evidence for seafood is stronger than for omega-3 supplements. Our guide to what EPA and DHA do sets out the research and the label wording FDA allows.

Count EPA plus DHA, not "fish oil"

A front-of-pack figure such as "1,000 mg fish oil" is the weight of the oil, not of the omega-3s inside it. The Linus Pauling Institute explains that in natural fish oil the fatty acids sit in triglycerides, often with only one of the three an omega-3, so up to 70% of the fatty acids can be other types, while ethyl-ester oils are concentrated and supply more EPA and DHA per gram. EPA and DHA content varies between products, so read the label. When FDA reviewed the market in 2019 it noted supplements sold with combined EPA and DHA anywhere from under a milligram to 8 grams a day.

So go to the Supplement Facts panel, find the EPA and DHA lines, then check the serving size. FDA's labeling guide says a serving is the largest amount the label recommends per eating occasion, so directions of "1 to 3 softgels" mean the panel describes 3. As arithmetic, an invented label listing 180 mg EPA and 120 mg DHA per softgel, with a serving of two softgels, supplies 600 mg of the two together. A search for fish oil softgels with EPA and DHA on Amazon (opens in a new tab) matches those words, and the panel on the pack is what counts.

Choose the source: fish, krill, cod liver or algae

NCCIH describes five kinds. Fish oil supplies EPA and DHA. Fish liver oil, such as cod liver oil, also contains vitamins A and D in amounts that vary by product, and NCCIH notes both can be harmful in excess. Krill oil carries its omega-3s in phospholipids, and the Linus Pauling Institute notes it is considered comparable to fish oil as a source of EPA and DHA. Algal oil is a vegetarian source of DHA, and some also contain EPA. Flaxseed oil provides ALA, a different omega-3 that the body converts to EPA and DHA only in small amounts. Searches for krill oil on Amazon (opens in a new tab) and algal oil with DHA and EPA on Amazon (opens in a new tab) show those kinds, and our guide to fish oil and algae oil compares them.

Check freshness and outside testing

Omega-3 fats oxidize easily, and oxidized oil smells and tastes rancid. A 2015 analysis of 171 omega-3 products sold in Canada found that half of those with usable results exceeded at least one voluntary limit for oxidation, though most of its authors work for a company that sells an omega-3 product. A commentary on it noted that the health effects of oxidized fish oil supplements are not yet established. Our guide to omega-3 freshness, mercury and labels goes through the numbers.

Outside checks exist, and all are voluntary. USP says its Verified Mark means the product contains the listed ingredients in the declared amounts and does not contain harmful levels of specified contaminants. NSF certifies to a dietary-supplement standard that includes a label-claim review and a contaminant review. IFOS, run by SGS Nutrasource, is specific to fish oil, and the program says it posts results by lot number. Those descriptions are the programs' own, and a mark speaks to what is in the bottle, not to whether the supplement will do anything for you. Searches for USP Verified fish oil on Amazon (opens in a new tab), NSF certified omega-3 on Amazon (opens in a new tab) and IFOS certified fish oil on Amazon (opens in a new tab) match words only, so confirm the mark on the pack and in the program's own listing.

Prescription omega-3 is a different product

NCCIH says several omega-3 products are approved as prescription drugs, used with diet to reduce triglycerides in people whose levels are very high. It adds that their composition and regulation differ from typical supplements, so their effects may not be the same. The FDA-approved label of Lovaza (omega-3-acid ethyl esters) describes it as an adjunct to diet for adults with severe hypertriglyceridemia, triglycerides of 500 mg/dL or more, at four 1-gram capsules a day, and Vascepa (icosapent ethyl) contains EPA only. A shelf supplement is not a substitute for either. If a clinician has prescribed one, ask before changing it.

Be wary of big claims

FDA lets a supplement label describe how a nutrient affects the body's normal structure or function, if the label states that FDA has not evaluated the claim and that the product is not intended to diagnose, treat, cure or prevent any disease. FDA does not approve those claims beforehand, and a product represented as treating or preventing a disease is regulated as a drug. FDA has also said it does not intend to object to some "qualified health claims" about EPA and DHA, but only in its own wording, with a sentence admitting the evidence is limited and, for the 2019 wordings, among other conditions at least 0.8 g of EPA and DHA per serving. A listing that promises more deserves caution.

A ceiling, not a target

In a 2019 letter, FDA concluded that taking up to 5 grams a day of EPA and DHA does not raise the risk of excessive bleeding, based on trials that measured bleeding episodes and blood loss, and that supplements providing no more than 5 grams a day as labeled are safe and lawful for carrying a health claim. It could draw no conclusion about bleeding above 5 grams because trials had not tested those doses. FDA had earlier applied a limit of 3 grams a day from food and supplements together. Those are ceilings, not suggested doses. Follow the daily amount on your label, and ask a clinician before going higher.

Who should speak to a clinician first

• Pregnant or breastfeeding. NCCIH advises consulting your health care provider first. FDA and EPA advise 8 to 12 ounces a week of a variety of lower-mercury seafood, and the 2025-2030 guidelines tell women to talk to their provider about a prenatal vitamin.
• Children. NCCIH says to consult a child's provider before giving a child an omega-3 supplement.
• Blood-thinning medicine. NCCIH lists medicine that affects blood clotting. The Lovaza label says omega-3 acids may prolong bleeding time and that patients taking an anticoagulant or another drug affecting coagulation should be monitored.
• Fish or shellfish allergy. NCCIH lists seafood allergy. The Lovaza and Vascepa labels say it is not known whether people with fish or shellfish allergies face a higher risk of reaction, and advise caution.
• Heart rhythm conditions. The Lovaza label reports a possible link to more frequent recurrences of atrial fibrillation or flutter in people who already have it, and the Vascepa label reports more hospitalizations for these rhythms in a high-risk trial. Those are prescription-strength products, but ask if you have a rhythm condition.
• Everyone. FDA advises talking to your doctor, pharmacist or other health care professional before using any dietary supplement, because some interact with medicines.

Where the links go

Links marked "on Amazon" open an Amazon search for the words in the link. Amazon decides what appears, and results can include products that do not meet the criteria above, so check each listing against the label.

Read next

• What EPA and DHA do: the research and the wording FDA allows.
• Fish oil vs algae oil: sources, forms and allergy cautions.
• Omega-3 oxidation, mercury and labels: freshness, fish advice and the panel.

The label on the pack in front of you is the authority on dose, ingredients and warnings, ahead of any article, this one included. If you have a health condition or take medicines, ask your doctor or pharmacist before you start.