Omega-3 EPA and medications.
Omega-3 EPA is classified as a foundation supplement in the Distil database, evidence Grade A. The page below lists every medication we have explicitly assessed it against.
Omega-3 EPA and DHA are the marine fats linked to heart, brain, joint, and mood health, and the sensible measure is the combined EPA plus DHA on the label, not the total fish oil weight. For general health, 1 to 2g daily is the usual range, with EPA-dominant ratios favoured for cardiovascular and inflammation goals and DHA-dominant in pregnancy. The evidence is genuinely strong, but there is an honest caveat: at pharmaceutical doses above roughly 1.8g per day, trials show a dose-dependent rise in atrial fibrillation risk, concentrated in people with prior AF, established heart disease, or athletic slow heart rates. At standard supplement doses in healthy adults, large trials found no meaningful AF signal, and dietary fish is not the risk. Omega-3 mildly thins the blood, so flag it if you take warfarin or other anticoagulants, and mention it before surgery. It pairs well with vitamin E to prevent oxidation. Take it with food to avoid fishy burps.
Below are the 15 documented pairs we have explicitly assessed for Omega-3 EPA: 13 amber and 2 green. The pairs cluster around 3 mechanisms: Additive antiplatelet effect, Narrow-therapeutic-index prescriber awareness, and COX-2 selective (platelet-sparing). Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Additive antiplatelet effect
High-dose fish oil (omega-3) can mildly reduce platelet stickiness, which may add to the blood-thinning effect of acenocoumarol. The effect is usually small at typical doses. If you take acenocoumarol and use high-dose omega-3, mention it to your anticoagulant clinic and watch for easy bruising.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
At supplement doses below 1 gram of EPA+DHA per day, fish oil adds little to apixaban's bleeding risk. At higher cardiology doses (3 grams per day and above) the antiplatelet effect is more meaningful and the combined bleeding risk rises. Apixaban has no INR test to monitor this, so tell your GP what dose of fish oil you take.
Standard supplement doses of fish oil (under 1 gram of EPA+DHA per day) add only marginally to the antiplatelet effect of aspirin. At higher cardiology doses (3 grams per day and above), the combination meaningfully increases bleeding risk. Tell your GP what dose you take.
Standard supplement doses of fish oil (under 1 gram of EPA+DHA per day) add only marginally to the antiplatelet effect of clopidogrel. At higher cardiology doses (3 grams per day and above), the combination meaningfully increases bleeding risk.
At supplement doses below 1 gram of EPA+DHA per day, fish oil adds little to dabigatran's bleeding risk. At higher cardiology doses (3 grams per day and above) the antiplatelet effect is more meaningful and the combined bleeding risk rises. Dabigatran has no INR test to monitor this, so tell your GP what dose of fish oil you take.
High-dose omega-3 has a mild antiplatelet effect that adds to diclofenac's. At typical supplement doses and short-course NSAID use, the combined effect is usually mild. At high doses or for chronic NSAID use, the additive bleeding tendency is worth knowing about.
At supplement doses below 1 gram of EPA+DHA per day, fish oil adds little to edoxaban's bleeding risk. At higher cardiology doses (3 grams per day and above) the antiplatelet effect is more meaningful and the combined bleeding risk rises. Edoxaban has no INR test to monitor this, so tell your GP what dose of fish oil you take.
High-dose omega-3 (typically more than 3g of combined EPA plus DHA per day) has a mild antiplatelet effect that adds to ibuprofen's. At typical supplement doses of 1 to 2g and short-course NSAID use, the combined effect is usually mild. At high doses or for chronic NSAID use, the additive bleeding tendency is worth knowing about.
High-dose omega-3 has a mild antiplatelet effect that adds to naproxen's. At typical supplement doses and short-course NSAID use, the combined effect is usually mild. At high doses or for chronic NSAID use, the additive bleeding tendency is worth knowing about.
At supplement doses below 1 gram of EPA+DHA per day, fish oil adds little to rivaroxaban's bleeding risk. At higher cardiology doses (3 grams per day and above) the antiplatelet effect is more meaningful and the combined bleeding risk rises. Rivaroxaban has no INR test to monitor this, so tell your GP what dose of fish oil you take.
Standard supplement doses of fish oil (under 1 gram of EPA+DHA per day) add only marginally to the antiplatelet effect of ticagrelor. At higher cardiology doses (3 grams per day and above), the combination more meaningfully increases bleeding risk. The combination is worth flagging before any planned surgery or dental procedure.
At supplement doses below 1 gram per day, omega-3 fish oil has minimal effect on INR. At higher doses (3 grams per day and above) used for triglyceride lowering, the antiplatelet effect is more meaningful and INR can shift. Tell your GP what dose you take if you are on warfarin.
Narrow-therapeutic-index prescriber awareness
Omega-3 fish oil and lithium are often taken together on purpose, because omega-3 has been studied as a mood support added on top of lithium and is generally well tolerated. There is no good evidence that omega-3 changes your lithium blood level. The reason to mention it is that lithium has a narrow safe range, and at higher fish oil doses (around 3 grams a day or more) omega-3 has a mild blood-thinning effect, so it is worth telling the doctor who manages your lithium what dose you take and keeping to your usual lithium blood tests.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
COX-2 selective (platelet-sparing)
Celecoxib is a COX-2 selective anti-inflammatory, so unlike standard anti-inflammatories such as ibuprofen or naproxen it has little effect on platelets and bleeding. That means adding fish oil is much less of a bleeding concern with celecoxib than with a standard NSAID. Celecoxib does carry its own stomach and heart-related cautions that are separate from fish oil, so follow the advice you have been given for the drug itself.
Etoricoxib is a COX-2 selective anti-inflammatory, so unlike standard anti-inflammatories such as ibuprofen or naproxen it has little effect on platelets and bleeding. That means adding fish oil is much less of a bleeding concern with etoricoxib than with a standard NSAID. Etoricoxib does carry its own stomach and heart-related cautions that are separate from fish oil, so follow the advice you have been given for the drug itself.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyWant this checked across everything you take?
This page checks the pairs you enter. The personalised Distil report goes further:
- the same graded, cited interaction check across your whole stack, not just the pairs you thought to type in
- where your current routine may be leaving you short of your goals
- the evidence-backed compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 for the first 25 customers. The interactions check is one section of it, and you can read a real one in full before you buy.
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