Omega-3 (EPA/DHA)

Omega-3 · Omega-3 fatty acids · n-3 PUFA · Fish Oil · EPA · DHA

Snapshot

Indications	Contraindications
Hypertriglyceridemia¹ Cardiovascular risk reduction¹ Preterm birth prevention² Adjunct in depression³ Migraine prophylaxis⁴ Mild cognitive impairment¹ Exercise-induced muscle soreness^{5, 6}	Fish allergy⁷ Shellfish allergy with krill oil⁷

Omega-3 fatty acids, chiefly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), come from fish, fish oil, krill oil, and algal oil¹. They are built into cell membranes and shift eicosanoid signaling toward less inflammation¹. Supplementation is used to lower triglycerides¹ and cardiovascular risk, to reduce preterm birth in pregnancy, as an adjunct in depression, and for migraine prophylaxis. Patients eating little oily fish, including vegetarians and vegans, have the lowest EPA and DHA intake.

The cardiovascular evidence is split: a Cochrane review found slightly fewer cardiovascular deaths and coronary events but no effect on all-cause mortality or stroke¹, while a 13-trial meta-analysis found lower rates of myocardial infarction and coronary heart disease death¹. Benefit has been most consistent with EPA-only prescription preparations, and a 2026 trial in hemodialysis patients found fewer serious cardiovascular events. In collegiate football players, a 2021 non-randomized study found a season of supplementation blunted a blood marker of axonal injury; no trial has replicated it. Products deliver omega-3s as triglycerides, ethyl esters, free fatty acids, or phospholipids, which differ in bioavailability; see Form comparison¹.

The most consequential caution is arrhythmic: trials of high-dose supplementation in people with or at high risk of cardiovascular disease found a slight increase in atrial fibrillation¹. Per product labeling for prescription omega-3s, patients on anticoagulants are monitored periodically for changes in international normalized ratio (INR)¹.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

65 sources, 53 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources