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Ingredient guide

Best time to take fish oil

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

Take fish oil with a meal that contains some fat. In one study, a high-fat meal raised EPA absorption from ordinary fish oil from 69% to 90%, and tripled absorption from ethyl ester products. Morning or night matters less: no study in our sources compares the two.1

Key facts

  • During low-fat eating, only 3 of 50 people absorbed even half as much from an ethyl ester product as they did with high-fat meals.2
  • A prescription omega-3 medicine may be taken as one daily dose or split into two.3
  • Like other fats, about 95% of the omega-3s you swallow are absorbed.4
  • Red blood cell levels reflect months of intake, so regular use matters more than the hour of day.4,5

With a meal that has some fat

In a study of male volunteers, taking fish oil with a high-fat meal (44 g of fat) instead of a low-fat one (8 g) raised absorption of EPA from ordinary fish oil from 69% to 90%, and roughly tripled absorption of EPA and DHA from fish oil ethyl esters, to about 60%.1

During a period of low-fat eating, only 3 of 50 adults taking a single 4 g dose of an ethyl ester product absorbed even half as much EPA and DHA as they did during a period of high-fat eating.2

Ethyl esters need a fat-digesting enzyme, pancreatic lipase, that a fatty meal stimulates, which is why they depend on the meal most. Oils in the natural triglyceride form are less sensitive, but in the same study they were still absorbed better with fat.1,2

Like other dietary fats, omega-3s are absorbed efficiently, at a rate of about 95%.4

In the clinical studies of a prescription omega-3 medicine, the capsules were taken with meals, and the daily amount may be taken at once or split into two doses.3

Once a day or split

The prescription product's label allows the daily amount as a single dose or as two doses, and no source here shows an advantage either way for supplements. Splitting the amount can make it easier to take each part with a meal.3

Morning or night?

No study in our sources compares morning with evening doses. Because absorption depends on the meal, the better time is whichever meal you eat reliably and that contains some fat, whether that is breakfast or dinner.1

Over weeks, a steady habit counts for more than the clock. Red blood cell EPA took about 28 days to make half its rise in a 12-month study, so what moves it is daily use, not the hour.5

Krill oil, algal oil and ethyl esters

The same advice applies to krill and algal oils, which are fats too. If a label says the omega-3s are ethyl esters, taking them with a meal that has fat matters most.1,2

If it gives you reflux or fishy burps

Burping, indigestion and a change in taste were the most common side effects of a prescription omega-3, and heartburn, nausea and an unpleasant taste are the usual ones with supplements. In the prescription product's studies, doses were taken with meals.3,6

If side effects persist, or if you take a blood thinner, ask your pharmacist or doctor before carrying on.

Questions people ask

Can I take fish oil on an empty stomach?

You can, but less may be absorbed. In one study, absorption of fish oil ethyl esters with a low-fat meal was about a third of that with a high-fat meal.1

Is there a best time to take omega-3 krill oil?

No study in our sources tested krill oil timing. It is an oil like fish oil, so the same advice holds: take it with a meal that contains some fat, at whatever time suits you.1

Does the timing matter with my medicines?

If you take a blood thinner or an antiplatelet medicine, ask your pharmacist before adding fish oil. The concern NIH and the prescription label describe is the combination, not the time of day.3,6

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Sources

  1. Lawson LD, Hughes BG. Absorption of eicosapentaenoic acid and docosahexaenoic acid from fish oil triacylglycerols or fish oil ethyl esters co-ingested with a high-fat meal. Biochem Biophys Res Commun. 1988;156(2):960-963. Opened 2026-10-07.
  2. Davidson MH, Johnson J, Rooney MW, Kyle ML, Kling DF. A novel omega-3 free fatty acid formulation has dramatically improved bioavailability during a low-fat diet compared with omega-3-acid ethyl esters: the ECLIPSE study. J Clin Lipidol. 2012;6(6):573-584. Opened 2026-10-07.
  3. Omega-3-acid ethyl esters capsules: prescribing information (Waylis Therapeutics). DailyMed, U.S. National Library of Medicine. Published March 11, 2026. Opened 2026-10-07.
  4. National Institutes of Health, Office of Dietary Supplements. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. Updated August 22, 2025. Opened 2026-10-07.
  5. Katan MB, Deslypere JP, van Birgelen AP, Penders M, Zegwaard M. Kinetics of the incorporation of dietary fatty acids into serum cholesteryl esters, erythrocyte membranes, and adipose tissue: an 18-month controlled study. J Lipid Res. 1997;38(10):2012-2022. Opened 2026-10-07.
  6. Office of Dietary Supplements, National Institutes of Health. Omega-3 Fatty Acids: Fact Sheet for Consumers. Updated July 18, 2022. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.