Omega-3 and Antidepressants: What Studies Show

Omega-3 fatty acids — particularly EPA — have been studied extensively as adjunctive treatment for depression. Cochrane reviews and Beyond Blue resources describe the evidence as suggesting modest benefit when added to standard antidepressant treatment, particularly for depression with higher EPA content in the supplement.

What the evidence shows

Cochrane reviews of omega-3 for depression suggest modest benefit for supplementation with EPA-rich preparations at doses typically above 1000mg EPA per day. Effect sizes are small to moderate. Benefit appears greater as an adjunct to antidepressant medication than as monotherapy. Some studies suggest particular benefit for depression associated with inflammation.

EPA versus DHA

Most positive research has been for EPA (eicosapentaenoic acid) rather than DHA (docosahexaenoic acid). Products marketed for cardiovascular health typically emphasise DHA; products marketed for mood may emphasise EPA. Check the label — the ratio of EPA to DHA matters.

Practical considerations

Standard fish oil supplements are safe alongside all common antidepressants. High-dose fish oil can have mild blood-thinning effects — worth discussing if you are on blood thinners or having surgery. Getting omega-3 from oily fish (salmon, sardines, mackerel) two to three times weekly is a food-based alternative. Vegetarian sources (algae-based supplements) exist but are more expensive. Read more about supplements and antidepressants before adding a new product.

What to flag to your prescriber

Raise these at any review

Any unusual bleeding when combining high-dose fish oil with your antidepressant.
Persistent depression despite standard treatment plus supplementation.
Digestive upset from fish oil (usually manageable by taking with food).
Fishy breath or reflux (usually reduced with enteric-coated preparations).

Frequently asked questions

Can I take fish oil with my antidepressant?

Yes. Standard-dose fish oil is safe alongside common antidepressants.

How much omega-3 helps depression?

Positive research has typically used above 1000mg EPA per day. Discuss dose with your prescriber.

Should I take EPA or DHA?

Most positive depression research has focused on EPA. Products marketed for mood typically emphasise EPA content.

Evidence and sources referenced

NICE Guideline NG222 — Depression in adults: treatment and management (United Kingdom).
Royal Australian and New Zealand College of Psychiatrists (RANZCP) — Clinical Practice Guidelines for Mood Disorders.
NPS MedicineWise — prescriber and patient resources on antidepressant treatment (Australia).
Royal College of Psychiatrists — patient information on antidepressants.
TGA and FDA — product information for SSRI and SNRI medication classes.
Maudsley Prescribing Guidelines in Psychiatry — prescribing patterns and side-effect timelines.