Does fish oil help with blood pressure? What the research does and doesn't show

The evidence doesn't support fish oil at typical over-the-counter doses as a meaningful blood pressure treatment. The largest dose-response analysis found a real effect, but only at 2 to 3 grams a day of combined EPA and DHA — several times a standard softgel — and even then the change was small, a few points on the cuff.

What the evidence doesn't support

It doesn't support fish oil as a substitute for blood pressure medication, or as something that reliably lowers blood pressure at the doses found in a typical over-the-counter softgel (usually 300 to 600 mg of combined EPA and DHA a day). It doesn't support the idea that more is always better either — the dose-response relationship isn't a straight line, and doses well above 3 grams a day didn't add proportionally more benefit in the data below. It doesn't support omega-3 raising blood pressure as a general finding — the concern about elevated blood pressure has not shown up as a consistent side effect across this research.

What the trials found

A 2022 dose-response meta-analysis in the Journal of the American Heart Association pooled 71 randomized controlled trials and 4,973 people, with a median combined EPA+DHA dose of 2.8 grams a day (interquartile range 1.3 to 3.6 grams). The relationship between dose and blood pressure change was J-shaped, not linear: the largest reductions showed up between 2 and 3 grams a day — systolic blood pressure down by about 2.6 mmHg and diastolic down by 1.6 to 1.8 mmHg at that range — with the effect stronger in people who already had hypertension, high lipids, or were older. Doses under 1 gram a day, closer to what a typical softgel provides, showed little to no measurable effect in this analysis.

A separate 2022 umbrella review in Frontiers in Nutrition, pooling 10 earlier meta-analyses (20 effect sizes), found a smaller average reduction across all included doses — about 1.2 mmHg systolic and 0.9 mmHg diastolic — reinforcing that whatever effect exists is modest, not the kind of change that would replace a prescribed treatment.

Neither analysis found omega-3 supplementation raised blood pressure as a general pattern across the trials pooled.

Questions people ask

Will fish oil lower blood pressure?

Only at doses well above what most over-the-counter softgels provide. The largest dose-response analysis found meaningful reductions concentrated at 2 to 3 grams of combined EPA and DHA a day — several times a typical 300 to 600 mg daily softgel dose — and even at that higher range, the average change was a few points, not a treatment-level effect.

How quickly does fish oil lower blood pressure?

The dose-response analysis above didn't report a specific time-to-effect; it pooled trials of varying lengths. There's no trial evidence to support an expectation of a fast or specific timeline for a blood pressure change from omega-3.

Can fish oil raise blood pressure?

Neither of the analyses above found omega-3 supplementation raising blood pressure as a general finding across the pooled trials. That said, any new supplement is worth mentioning to a doctor if you're monitoring your blood pressure closely.

Can I take fish oil with blood pressure medication?

Fish oil has a mild blood-thinning effect on its own, which becomes more relevant when combined with a blood thinner specifically, not blood pressure medication in general — see the fish oil and medication interactions page for the detail. Either way, this is worth raising with the prescribing doctor before combining anything with a blood pressure prescription.

Does fish oil lower cholesterol and blood pressure at the same time?

They're separate questions with separate evidence bases — see the fish oil and cholesterol page for what the triglyceride and LDL research shows, since the effective doses and findings differ between the two.

When to talk to a doctor

Blood pressure readings that are consistently elevated, or a diagnosis of hypertension, call for a doctor's evaluation and a treatment plan — not a supplement search. Fish oil is not a treatment for high blood pressure or hypertension, and nothing in the evidence above supports using it in place of prescribed medication or lifestyle changes a doctor recommends. If you take blood pressure medication, a blood thinner, or are pregnant or nursing, talk to a doctor before adding any supplement.

Related reading: fish oil and cholesterol: what the research does and doesn't show, fish oil and atrial fibrillation risk: what the research does and doesn't show, fish oil and medications: what to check, and how much fish oil should you take a day.