Omega-3 Fatty Acids for Chronic Sinusitis

Omega-3 is one of the few supplements that has been tested in chronic rhinosinusitis (CRS), but the evidence is thin. The best study, a single-blind trial of 164 adults with nasal polyps, added 3 g of omega-3 a day to a budesonide steroid spray after a short course of oral steroids had cleared the polyps. Polyps came back at a similar rate in both groups, but they returned later in the omega-3 group.

That makes omega-3 a reasonable add-on to discuss with your ENT if polyps keep regrowing between steroid courses. It is not a replacement for steroid sprays, saline rinses, biologics or surgery, and there is no trial evidence for CRS without polyps.

Nasal polyps are one of the clearest examples of lipid-driven inflammation. Cells in the sinus lining turn arachidonic acid, an omega-6 fat, into leukotrienes and prostaglandin D2, signals that recruit eosinophils (allergy-type white blood cells) and swell the tissue. In a 2022 study of nasal secretions, leukotriene E4 and prostaglandin D2 rose with polyp severity, and leukotriene E4 was highest in people with AERD.

EPA and DHA, the main omega-3s in fish oil, compete with arachidonic acid for the same enzymes, so a higher omega-3 intake can shift production toward less inflammatory signals. In a small AERD study, a high-omega-3, low-omega-6 diet lowered urinary leukotriene E4 and a prostaglandin D2 by-product within two weeks.

Omega-3s are also the raw material for resolvins, protectins and maresins, which help switch inflammation off once it has done its job. Tissue studies show this resolution system is disturbed in CRS: resolvin D2 is raised in sinus tissue with and without polyps, and maresin levels are low in the blood but high in the nasal secretions of people with polyps.

What these studies can't show is whether taking omega-3 corrects that imbalance inside the sinuses. An older experiment makes the gap clear: 3.5 g/day of EPA for 8 weeks blunted the blood-flow and eosinophil response to pollen in the noses of 7 people with hay fever, yet their symptoms were no better.

The nasal polyp trial used 3 g of omega-3 a day, taken alongside a budesonide steroid spray after a short course of oral steroids had shrunk the polyps. The published abstract doesn't break that dose into EPA and DHA, so the closest practical match is a product supplying about 3 g of combined EPA and DHA daily.

Read the label for EPA plus DHA rather than total fish oil: a standard 1,000 mg capsule often contains only about 300 mg of the two combined, so 3 g may take several concentrated capsules. Take them with meals to improve absorption and reduce fishy burps, and keep using your prescribed spray and saline rinses.

The main evidence is a single-blind randomised trial published in 2020 in the American Journal of Rhinology & Allergy. It enrolled 164 adults with grade II nasal polyps, treated them with a short course of oral steroids until the polyps subsided, then split them evenly: one group used budesonide nasal spray plus 3 g/day of omega-3, the other used the spray alone.

Omega-3 did not significantly change how many people had polyps return (P = .1) or how large the recurrent polyps were (P = .66). It did significantly lengthen the time before polyps came back (P < .0001). The author suggested this could reduce the need for repeat oral steroid courses, but that was not measured directly, and with no placebo capsule the result is open to bias.

AERD combines asthma, nasal polyps and reactions to aspirin and similar painkillers, and it is driven by overproduction of leukotrienes. In a 2018 Harvard pilot, 10 adults with AERD cut dietary omega-6 to under 4 g/day and raised omega-3 to over 3 g/day for two weeks. Their SNOT-22 sinus symptom score fell by 15.1 points and asthma control improved slightly, with no change in lung function. There was no control group, and participants knew what they were eating.

An older pilot points the other way. In 1988, 10 people with aspirin-intolerant asthma ate a fish-oil-enriched diet providing about 3 g/day of EPA for six weeks. Symptom scores didn't change, but peak airflow fell and reliever inhaler use rose in weeks five and six. Both studies are tiny, but together they are a reason for people with AERD to involve their allergist before starting high-dose omega-3.

There is no placebo-controlled trial of omega-3 in CRS, no trial in CRS without polyps, and no study comparing it with the treatments that work best, such as steroid sprays, biologics or surgery. A 2026 systematic review of diet and rhinosinusitis found only 10 relevant studies, mostly observational, and called for properly randomised trials.

Smell is a related open question. Omega-3 reduced lasting smell loss after endoscopic skull-base surgery in a 110-patient trial, but a trial in COVID-related smell loss found no benefit, and neither studied smell loss caused by CRS.

At 3 g/day, omega-3 is generally well tolerated. The usual complaints are fishy burps, reflux and loose stools, which ease when capsules are taken with meals. The European Food Safety Authority considers long-term intakes of up to about 5 g/day of EPA and DHA combined safe for adults.

Two risks matter more at this dose. Omega-3 has a mild blood-thinning effect, which is relevant if you take anticoagulants or are having surgery, including sinus surgery. And in large heart trials, doses above 1 g/day were linked to a higher risk of atrial fibrillation, an irregular heart rhythm (hazard ratio 1.49, against 1.12 at lower doses).

Omega-3's interactions come mostly from its mild blood-thinning effect and, at higher doses, a small drop in blood pressure. It has no known interaction with steroid nasal sprays; the two were used together in the nasal polyp trial.