Fish Oil May Worsen Long COVID and ME/CFS

Fish oil supplements are everywhere. They are touted as the supplement for lowering inflammation. So for those dealing with inflammatory conditions like long COVID, chronic fatigue syndrome (ME/CFS), or fibromyalgia, these supplements seem like an obvious choice.

But here's the problem: fish oil pills might actually make your symptoms worse.

If you have a postviral condition, your body's inflammation system is already broken. Adding more fish oil to the mix is like throwing gasoline on a fire that won't go out.

Here's what you need to know.

How Fish Oil Is Supposed to Work (But Doesn't in Postviral Illness)

Fish oil contains two main omega-3 fatty acids: EPA and DHA. Your body uses these to make powerful anti-inflammatory molecules called specialized pro-resolving mediators (SPMs). These include resolvins, protectins, and maresins.

Think of SPMs as your body's cleanup crew. They don't just reduce inflammation—they actively help your immune system "turn off the alarm" and clean up after an infection. They help immune cells clear debris, repair tissue, and restore balance.

This process is called the "resolution pathway." It's how healthy people recover from infections and injuries.

But in postviral illness, this pathway is broken.

Why Your Inflammation Won't Turn Off

In chronic fatigue syndrome (ME/CFS) and long COVID, one of your body's main immune "fire alarms"—the NLRP3 inflammasome—often stays switched on. This drives ongoing immune activation and what doctors call "cytokine storms" (Paul, 2021; Rodrigues et al., 2021).

During severe COVID, researchers found that patients had lower levels of SPMs in their blood. The sicker the patients were, the lower their SPM levels. Normally, SPMs help calm the inflammasome, but when they're too low, the brakes on inflammation don't work properly.

This means that even if you take fish oil capsules, your body may not be able to convert enough EPA and DHA into the inflammation-resolving molecules—the SPMs—you actually need.

It's like having a broken factory. You can keep sending in raw materials, but the finished product never comes out.

The Research: Fish Oil Supplements Don't Help Long COVID Symptoms

The evidence backs this up. A recent study tested omega-3 supplements in healthcare workers with long COVID. The supplements improved their blood omega-3 levels, but symptoms didn't improve compared to placebo (Sarkar et al., 2024).

This makes sense when you understand that the problem isn't a lack of omega-3s—it's a broken resolution pathway.

Four Reasons Fish Oil Pills May Actually Harm Postviral Patients

1. Raw Materials Aren't the Same as Finished Products

Fish oil gives you EPA and DHA, but your body still needs to convert these into SPMs. If that conversion process is broken (which it often is in postviral conditions), you're just adding more raw materials to a backed-up system.

2. They Don't Fix Microclots

Many long COVID patients have unusual blood clots called amyloid fibrin microclots. These clots are extremely resistant to breakdown. Omega-3s can reduce how sticky your blood platelets are, but they cannot dissolve these stubborn microclots (Pretorius et al., 2021; Rasouli et al., 2025).

3. Most Fish Oil Supplements Are Rancid

Surveys of retail fish oil products show that many are oxidized (rancid) before you even buy them (Syal, 2022). Oxidized oils have been linked to vascular inflammation in some studies (Harvard Health, 2023; Albert et al, 2013), and while the effects in humans aren't fully clear, why risk taking rancid supplements when fresh seafood is available?

4. Wrong EPA to DHA Ratios

Most commercial fish oils don't have the right balance of EPA to DHA for optimal brain and body function. This matters more when your system is already struggling.

EPA and DHA have different jobs in your body. EPA is better at reducing inflammation and supporting mood, while DHA is crucial for brain structure and cognitive function. Many cheap fish oil supplements are heavy on DHA (because it's easier to extract from certain fish) but light on EPA.

For people with chronic fatigue syndrome (ME/CFS) or long COVID, this imbalance could be problematic. Your inflamed system might benefit more from EPA's anti-inflammatory effects, but you're getting mostly DHA instead. Natural seafood, on the other hand, provides EPA and DHA in ratios that have supported human health for thousands of years.

The Better Strategy: Real Seafood Instead of Supplements

This doesn't mean omega-3s aren't important—they absolutely are. But there's a better way to get them.

Eat whole seafood instead of taking capsules.

Fatty fish like salmon, sardines, mackerel, and anchovies deliver omega-3s in their natural form, along with:

• High-quality protein for tissue repair

• B vitamins for energy production

• Selenium and other antioxidants

• Other bioactive compounds that support recovery

Real seafood is also much less likely to be rancid compared to processed supplements that may have sat on shelves for months.

What This Means If You Have Long COVID, Chronic Fatigue Syndrome, or Fibromyalgia

Do you feel worse when taking fish oil supplements? You're not imagining it. Many postviral patients report that fish oils make their symptoms worse, not better. This is especially relevant for more severe cases, which have the highest inflammatory load.

The issue isn't that you need more omega-3s. The issue is that your body's inflammation resolution system is stuck in "on" mode. Focus on eating real seafood 2-3 times per week instead.

The Future: Direct SPM Supplementation

Looking ahead, researchers are working on a more targeted approach. Instead of giving people fish oil and hoping their bodies convert it properly, scientists are testing direct SPM supplementation.

This means providing the actual inflammation-resolving molecules (like resolvins) instead of just the raw materials. Early research suggests this could be much more effective for people with broken resolution pathways (Serhan, 2023).

Bottom Line: Skip the Capsules, Eat the Fish

For people with chronic fatigue syndrome (ME/CFS), fibromyalgia, or long COVID, fish oil supplements are not the answer. In fact, they may make things worse.

Here's what the science tells us:

• They don't break down microclots

• An overactive inflammasome blocks their benefits

• Many commercial products are rancid

• Most have wrong EPA:DHA ratios

The smarter approach? Skip the capsules and eat real seafood instead. Your recovery depends on supporting your body's natural processes, not overwhelming them with processed supplements that may do more harm than good.

References

Serhan CN, Libreros S, Nshimiyimana R. E-series resolvin metabolome, biosynthesis and critical role of stereochemistry of specialized pro-resolving mediators (SPMs) in inflammation-resolution: Preparing SPMs for long COVID-19, human clinical trials, and targeted precision nutrition. Semin Immunol. 2022;59:101597. doi:10.1016/j.smim.2022.101597

Syal R. Revealed: many common omega-3 fish oil supplements are 'rancid'. The Guardian [Internet]. January 17, 2022. Available from: https://www.theguardian.com/environment/2022/jan/17/revealed-many-common-omega-3-fish-oil-supplements-are-rancid

Rodrigues TS, de Sá KSG, Ishimoto AY, et al. Inflammasomes are activated in response to SARS-CoV-2 infection and are associated with COVID-19 severity in patients. J Exp Med. 2021;218(3):e20201707. doi:10.1084/jem.20201707

Pretorius E, Vlok M, Venter C, et al. Persistent clotting protein pathology in Long COVID/Post-Acute Sequelae of COVID-19 (PASC) is accompanied by increased levels of antiplasmin. Cardiovasc Diabetol. 2021;20(1):172. Published 2021 Aug 23. doi:10.1186/s12933-021-01359-7

Rasouli R, Hartl B, Konecky SD. Low-intensity ultrasound lysis of amyloid microclots in a lab-on-chip model. Front Bioeng Biotechnol. 2025;13:1604447. Published 2025 Jun 30. doi:10.3389/fbioe.2025.1604447

Paul BD, Lemle MD, Komaroff AL, Snyder SH. Redox imbalance links COVID-19 and myalgic encephalomyelitis/chronic fatigue syndrome. Proc Natl Acad Sci U S A. 2021;118(34):e2024358118. doi:10.1073/pnas.2024358118

Sarkar A, Speiser E, Dara S, et al. The Feasibility of Omega-3 Supplementation Compared to Placebo in the Management of Long COVID Symptoms Among Healthcare Workers: A Randomized Controlled Trial. Cureus. 2024;16(12):e76148. Published 2024 Dec 21. doi:10.7759/cureus.76148

Harvard Health Publishing. The false promise of fish oil supplements. Harvard Health Blog. December 1, 2023. https://www.health.harvard.edu/blog/the-false-promise-of-fish-oil-supplements-202312012991

Albert BB, Derraik JG, Cameron-Smith D, et al. Oxidation of marine omega-3 supplements and human health. Biomed Res Int. 2013;2013:464921. doi:10.1155/2013/464921