How long does fish oil take to work?

Fish oil is absorbed into the bloodstream within hours of a dose, but "working" means something different depending on what's being measured. The dose-response trial that matches our exact serving sizes tracked a blood marker over about five months, not days or weeks. Outcome-focused research that found any effect took months to years, at doses higher than our labeled amount.

Three different timeframes, three different measurements

It helps to separate what happens fast from what's been measured slowly:

• Hours: absorption into the blood. A single-dose absorption study measured EPA and DHA appearing in plasma within hours of a meal-plus-fish-oil dose. This is also when gastrointestinal effects like a fishy aftertaste or burping tend to show up, if they do — see fish oil side effects.
• Months: a change in a blood biomarker. A five-month trial in 115 healthy adults gave one of five daily doses — 0, 300, 600, 900 or 1,800 mg of combined EPA and DHA — and measured the omega-3 index, a lab test of how much EPA and DHA sits in red blood cell membranes. It rose in a dose-dependent way; two of the five arms, 300 mg and 600 mg, are exactly our one- and two-softgel daily amounts. That trial didn't report an earlier timepoint, so we don't have a matched-dose reading for, say, four weeks in — five months is the closest measurement we have.
• Months to years: the outcome trials. The research that reported effects on things like memory measures or cardiovascular events ran considerably longer, and used doses well above ours: a cognition trial measured results at 24 weeks using 900 mg/day of DHA alone; a large heart-attack-survivor trial ran 3.5 years at 1 g/day; a prescription-drug cardiovascular trial ran nearly 5 years at 4 g/day. See fish oil benefits: what the research does and doesn't show for what those trials found and how their doses compare to a standard softgel.

What we can and can't say about our own serving

At Electric Tiger Omega-3's labeled amount (300 mg per softgel, 600 mg/day at two a day), the dose-response trial above is the closest matched evidence, and it measured a blood marker at five months — not a health outcome, and not a timeline for "feeling" anything. We haven't found a trial reporting how the omega-3 index changes at earlier timepoints at this dose, so we can't give you a week-by-week answer, and we're not going to invent one.

Questions people ask

How long does it take for fish oil to work?

Absorption into the blood happens within hours. The only dose-matched change we can point to — a blood marker called the omega-3 index — was measured at five months in a trial using our exact serving sizes. Outcome-focused research used higher doses and ran for months to years.

How long does omega-3 stay in your system?

We haven't found a trial reporting a clearance timeline at a standard over-the-counter dose. Omega-3s are stored in cell membranes rather than cleared quickly like a water-soluble nutrient, but we don't have a specific number to give you for our serving.

Does an omega-3 supplement actually work?

That depends what you mean by "work." At our labeled amount, the closest matched evidence shows a blood marker rising over time — a measurable biological effect, not a claim about symptoms or disease outcomes. See fish oil benefits: what the research does and doesn't show for the fuller picture, including where the evidence is thin.

How do subscription orders line up with how long a bottle lasts?

At the labeled two-softgel-a-day amount, a 100-softgel bottle is about a 50-day supply. Our subscription pricing is as low as $16.79 a bottle; delivery cadence is something you can adjust in your account to match how quickly you actually go through a bottle.

Sources

• Flock MR, et al. Determinants of erythrocyte omega-3 fatty acid content in response to fish oil supplementation: a dose-response randomized controlled trial. PMID 24252845.
• Lawson LD, Hughes BG. Absorption of eicosapentaenoic acid and docosahexaenoic acid from fish oil triacylglycerols or fish oil ethyl esters co-ingested with a high-fat meal. PMID 2847723.
• Electric Tiger Omega-3 Supplement Facts: product page.

Related reading: how much fish oil should you take a day, when is the best time to take fish oil, and fish oil benefits: what the research does and doesn't show.