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Medicines and supplements

Can you take fish oil with blood thinners?

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

Ask your pharmacist or doctor before combining. NIH says high doses of omega-3s may cause bleeding problems with warfarin or other anticoagulants, and the label of a prescription omega-3 medicine says people also taking an anticoagulant or antiplatelet medicine should be monitored periodically.1,2

Key facts

  • Fish oil can have antiplatelet effects at high doses, though it appears less potent than aspirin.3
  • Doses of 2 to 15 g a day of EPA and DHA might lengthen bleeding time.3
  • Fish oil might prolong clotting time, measured as INR, in people taking warfarin.3
  • In the prescription product's trials, longer bleeding times stayed within normal limits, but its use with anticoagulants has not been studied thoroughly.2

Your doctor may want to check on you

High doses of omega-3s may cause bleeding problems when taken with warfarin or other anticoagulants, and fish oil can have antiplatelet effects at high doses. Fish oil might also prolong clotting time, measured as INR, in people taking warfarin. The label of a prescription omega-3 medicine says people who also take an anticoagulant or an antiplatelet medicine should be monitored periodically.1,2,3

On the medicine's label

What is documented

NIH's consumer fact sheet says high doses of omega-3s may cause bleeding problems when taken with warfarin or other anticoagulant medicines. Its fact sheet for health professionals adds that fish oil can have antiplatelet effects at high doses and might raise the INR, the clotting test used to adjust warfarin.1,3

The label of a prescription omega-3 medicine, omega-3-acid ethyl esters, lists the concern under drug interactions. It says omega-3 acids may prolong bleeding time and that people taking it with an anticoagulant or another drug affecting clotting, such as an antiplatelet agent, should be monitored periodically. That label is why the effect above is marked as on the medicine's label.2

The research on how much this matters at supplement amounts is mixed. NIH points to the prescription labels' advice to monitor, and none of these sources names an amount of fish oil that removes the concern for someone on a blood thinner.3

Which blood thinners this covers

The sources name warfarin, anticoagulants as a group, and antiplatelet medicines. The warfarin label gives examples of each: heparin and dabigatran among anticoagulants, and aspirin and clopidogrel among antiplatelet agents.1,2,4

Apixaban, an anticoagulant, is not named with fish oil in these sources. Its MedlinePlus page names St. John's wort, aspirin and NSAIDs among the nonprescription products that may interact, and asks you to tell your doctor and pharmacist about every supplement you take. That is not a finding either way, so ask your pharmacist.5

How it is known

  • On the medicine's label: the prescription omega-3 label advises monitoring people who also take anticoagulants or antiplatelet agents.2
  • Reported in studies: NIH cites research in which fish oil raised the INR of people taking warfarin, and research on its antiplatelet effect at high doses.3

What to ask your pharmacist

  • Does my blood thinner or antiplatelet medicine fall under this caution?
  • Should my clotting tests be checked more often if I start or stop fish oil?
  • Does the amount of EPA and DHA in my product matter for me?
  • Do any of my other supplements, such as krill oil or cod liver oil, contain omega-3s too?

Bring the label of every supplement you take. Omega-3s are also found in krill, cod liver and algal oils, not only in products sold as fish oil.6

Questions people ask

Can I take omega-3 with apixaban?

The sources on this page do not name apixaban with fish oil. NIH and the prescription omega-3 label speak of anticoagulants in general, and MedlinePlus describes apixaban as an anticoagulant, so ask your pharmacist or the doctor who prescribed it before combining them.1,2,5

What about fish oil with daily aspirin?

Aspirin is an antiplatelet medicine, and the prescription omega-3 label advises monitoring people who take antiplatelet agents with it. NIH notes that fish oil's own antiplatelet effect at high doses appears weaker than aspirin's. Ask your doctor before combining them.2,3,4

Does krill oil or algal oil count?

The sources speak of omega-3s and fish oil in general, and krill, cod liver and algal oils all supply EPA or DHA. Ask your pharmacist about any of them.1,6

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Sources

  1. Office of Dietary Supplements, National Institutes of Health. Omega-3 Fatty Acids: Fact Sheet for Consumers. Updated July 18, 2022. Opened 2026-10-07.
  2. 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.
  3. 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.
  4. Warfarin sodium tablets: prescribing information (Amneal Pharmaceuticals). DailyMed, U.S. National Library of Medicine. Published June 3, 2026. Opened 2026-10-07.
  5. MedlinePlus. Apixaban. U.S. National Library of Medicine. Last revised October 15, 2025. Opened 2026-10-07.
  6. National Center for Complementary and Integrative Health, National Institutes of Health. Omega-3 Supplements: What You Need To Know. Last updated November 2024. Opened 2026-10-07.

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