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Does Fish Oil Expire? (Figure Out Whether It’s Gone Bad)

Isaac Robertson
Published by Isaac Robertson
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: March 20, 2023
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Science has found that heart-healthy omega-3 unsaturated fats from fish oil supplements can provide numerous health benefits to your body.

However, be aware that these supplements can get spoiled faster than you might expect.

It means they become less effective and may cause various health problems, from mild side effects like fishy burps to more serious conditions than those you wanted to prevent when you started taking the supplement.

To ensure the safe use of fish oil supplements, we’ve asked expert dietitians to answer the most common questions on the topic.

Read on to learn:

  • How to figure out whether it’s gone bad
  • How to store it after purchasing to keep it fresh longer
  • What you can experience after taking expired softgels.

Quick Summary

  • Fish oil can expire and be unsuitable for consumption due to improper storage, or if its expiry date is due.
  • A foul smell is one of the signs that your fish oil has expired when you open the container.
  • Manufacturers state that most fish oil supplements have a shelf life of up to two years.

Do Liquid Fish Oil Supplements Expire?

Liquid fish oil supplement on a bottle

Yes, liquid fish oil supplements can expire just like other forms.

Moreover, fish oil supplements can become oxidized, rancid, and unsuitable for consumption even within or not significantly past their expiration date, usually due to improper storage.

“Light, heat and oxygen are the primary factors that influence degradation rate. Even stored in the dark, fish oil may oxidize unacceptably within 30 days of storage, according to a review published in the 2013 edition of the journal ‘BioMed Research International.’” 

Although liquid fish oils are typically packed in a dark brown glass bottle through which light can’t pass, they go bad faster because they’re directly exposed to the air, light, or moisture after opening.

The oxidation can happen quickly, as soon as the bottle is opened and the supplement comes in contact with air.

It triggers chemical reactions in which the key omega-3 nutrients Eicosapentaenoic acid and Docosahexaenoic acid break down into lipid peroxides and further degrade to secondary by-products of oxidation such as cell-damaging aldehydes.

Do Fish Oil Capsules Expire?

A woman holding a piece of fish oil

Yes, fish oil capsules also expire.

According to studies, oxidation of fish oil may start within one month even if properly stored in a fridge or another cool, dark, and dry place at 39 degrees Fahrenheit [1], and despite the added antioxidants or other compounds that reduce oxidation, and the see-through barrier all softgels contain to stay fresh longer.

A study from the Journal of Nutritional Science has found that 50% of the tested supplements were below at least one of the safety standards for oxidation and determined that encapsulated, unflavored fish oil is the safest supplement form. [2]

Since all fish oil supplements are highly prone to oxidation, it’s wise to purchase a one-month supply at a time.

Also, educating yourself is important to minimize the possibility of experiencing undesired side effects.

So, that’s why it matters to learn and fully understand: 

  • How to tell if fish oil capsules are rancid and oxidized
  • How to properly store them
  • What the possible harmful effects of consuming expired and oxidized fish oil are

How to Know if Your Fish Oil Has Expired?

The following tips and steps can help you detect an oxidized and expired fish oil supplement that may have adverse effects on your health:

  1. Look into the “Best Before” date on the supplement package. If it’s out of date, my advice is to throw it away, but you may also take the following steps as most such products have a shelf life of 24 months from the production date.
  2. Run a quick product quality check. Purchase the supplement from a reputable company that sells high-quality products. Also, look for the third-party testing verification on the label that shows the product has met the quality standards and contains no contaminants or toxic compounds like mercury.
  3. Scan the capsule, paying attention to whether it’s clear with a transparent, even, and springy coating and light golden color. If the pill is murky and soft, even soggy, it indicates that it’s not fresh and may be spoiled, so get rid of it.
  4. Open the bottle or break open the capsule to smell the oil inside. If you notice a whiff of sour, rotten fishy, or foul odor, it’s an indicator of rancidity.
  5. Finally, taste the supplement. If it tastes rancid, has a strong unpleasant flavor, or fishy aftertaste, it’s probably gone off, and you shouldn’t consume it.

How Long Does Fish Oil Last After The Expiration Date?

According to some supplement manufacturers, most fish oil supplements can last for two years after the date they’re made (even significantly after expiration) if unopened, packaged, and stored properly.

Related Article:

Is Rancid Fish Oil Harmful?

Rancid fish oils can be harmful and toxic even in small doses for some people.

Besides reduced effectiveness and side effects such as heartburn, loose stools, and urinary tract infections, some studies have shown that taking rancid oil can: 

A close up image of holding a piece of fish oil capsule
  • Increase certain risk factors for Alzheimer’s disease and atherosclerosis
  • Have mutagenic effects
  • Cause inflammation, high blood pressure, and high cholesterol levels
  • Lead to organ damage

Especially in patients who have previously had a heart attack or suffered from any other heart disease. [3] [4] [5]


  1. Should Fish Oil Be Refrigerated?
    Once opened, liquid fish oil supplements should be refrigerated to slow down and reduce oxidation, whereas some liquid softgel capsules can be properly stored at room temperature but in a cool place without direct heat, moisture, or light exposure.
  2. Can I Take Fish Oil After the Expiration Date?
    Although it might not be deadly dangerous, I wouldn’t recommend taking fish oil after the expiration date as it’s less potent and won’t provide the expected health benefits (especially if it smells bad or appears slightly discolored because EPA and DHA, the essential omega-3 fatty acids from fish oil products, are highly susceptible to oxidation and can go rancid even before the valid conservative expiration date on the label).
    Expired fish oil supplements lose their potency, effectiveness, and taste, particularly if kept at room temperature.
  3. Why Is My Fish Oil Cloudy?
    Your fish oil supplement can become cloudy when it gets cooled in a refrigerator or freezer, just like olive oil or any other natural oil, because it contains a wide array of various fat types with different chemical structures that have different melting points.
    The cloudiness doesn’t determine the quality or freshness of a fish oil supplement.
  4. How Do You Dispose of Expired Fish Oil Pills?
    The best way to dispose of expired fish oil pills properly is to follow the specific disposal instructions on the supplement label.
    The FDA recommends that you find and contact a community drop-off center for unused medications and over-the-counter tablets, or mix the pills with used coffee grounds, put it into a sealed container, and throw it all in the trash. [6]
    Some people also suggest tossing them into your backyard compost pile or discarding them into soil fertilizer.

Can Fish Oil Supplements Expire?

Yes, fish oil supplements can expire just like any other food.

Now that you know what changes can happen to the supplement for different reasons, how they can reduce its effectiveness and affect your health, and what to take into consideration when detecting a spoiled product, you’re more likely to benefit from it, stay healthy, and on the safe side.

Let us know whether you boost your nutrition with fish oil and how effective you’ve found it.


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