Is it okay to take fish oil and krill oil together?

November 1, 2025 •

5 min read

According to the NIH Office of Dietary Supplements, the U.S. Food and Drug Administration recommends consuming no more than 5 grams per day of combined EPA and DHA from supplements. While both supplements contain these essential fatty acids, the question, "Is it okay to take fish oil and krill oil together?" is common among those seeking maximum benefits.

Quick Summary

Both fish oil and krill oil are rich in omega-3 fatty acids EPA and DHA, making them a potentially synergistic combination for enhanced health benefits. Their structural differences, with krill oil's phospholipid form offering better absorption and its antioxidant content providing added protection, can complement the higher EPA and DHA levels typically found in fish oil.

Key Points

Combining is generally safe: Most healthy individuals can take fish oil and krill oil together, potentially offering a broader spectrum of omega-3 benefits.
Complementary benefits: Fish oil provides a higher concentration of EPA and DHA, while krill oil offers better absorption and the antioxidant astaxanthin.
Mind the intake: Excessive intake from combining can lead to side effects. The FDA recommends an upper limit of combined EPA and DHA daily from supplements.
Check for interactions: Both supplements can affect blood clotting. Consult a doctor if you take blood-thinning medication or have a bleeding disorder.
Beware of allergies: If you have a shellfish allergy, you must avoid krill oil.
Consult a professional: Before combining, speak with a healthcare provider to ensure it is appropriate for your specific health conditions and goals.
Prioritize whole foods: Supplements should not replace a healthy diet. The best source of omega-3s is often through fatty fish.

What are fish oil and krill oil?

Fish oil, derived from the tissues of fatty fish like salmon, sardines, and mackerel, is a long-standing and widely researched source of omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In fish oil, the omega-3s are predominantly bound to triglycerides. Many studies support its use for cardiovascular health, reducing inflammation, and improving cognitive function. Fish oil is also typically more accessible and less expensive than krill oil.

Krill oil is extracted from tiny, shrimp-like crustaceans found in the Antarctic Ocean. It is also a source of EPA and DHA, but its omega-3s are primarily bound to phospholipids. This phospholipid structure may enhance absorption and bioavailability, meaning the body can utilize it more efficiently. Krill oil also contains a potent antioxidant called astaxanthin, which gives it a reddish color and provides additional anti-inflammatory and cellular protective effects. Krill are lower on the food chain, which can mean a lower risk of accumulating certain contaminants.

The potential synergistic benefits of taking both

Combining fish oil and krill oil can offer a synergistic approach to omega-3 supplementation by leveraging the unique strengths of each. This strategy is based on the idea that you can gain the advantages of both the higher dosage and research-backed history of fish oil, along with the superior absorption and antioxidant boost of krill oil.

Enhanced Absorption: Krill oil's phospholipid-bound omega-3s are thought to be more easily absorbed and delivered to specific tissues, including the brain. By combining it with fish oil, you can maximize the absorption of the omega-3s from both sources.
Increased Antioxidant Protection: The potent astaxanthin in krill oil offers added antioxidant benefits that fish oil lacks. This can help protect against oxidative stress and may offer additional anti-inflammatory effects.
Broadened Health Support: While both oils support heart and brain health, they may do so through slightly different mechanisms. A combination may therefore offer more comprehensive support. Some studies also indicate krill oil can be particularly effective at improving cholesterol profiles and managing PMS symptoms.

Comparison table: Fish oil vs. krill oil


Feature	Fish Oil	Krill Oil
Primary Source	Fatty fish like salmon, mackerel, and sardines.	Tiny crustaceans called krill.
Omega-3 Structure	Mostly in triglyceride form.	Mostly in phospholipid form.
Absorption Rate	Good, but potentially lower than krill oil.	Potentially better absorbed due to phospholipid form.
Antioxidants	Generally lacks potent antioxidants like astaxanthin.	Contains the powerful antioxidant astaxanthin.
Omega-3 Concentration	Typically higher concentration of EPA and DHA per serving.	Often lower concentration of EPA and DHA per serving.
Cost	Generally more affordable and accessible.	Typically more expensive due to harvesting costs.
Contaminant Risk	Can accumulate heavy metals, though most supplements are purified.	Lower risk of contaminants as krill are lower on the food chain.
Research	More extensively studied in human clinical trials.	Less extensive human research, but growing evidence.
Common Side Effects	Fishy burps, indigestion, nausea.	Gastrointestinal upset, less common fishy burps.

Potential risks and considerations

While taking fish oil and krill oil together is generally safe for most healthy individuals, there are important risks and considerations to keep in mind.

Risk of excessive omega-3 intake

Just because combining supplements can provide more benefits does not mean that more is always better. Excessive intake of omega-3s, from combining high doses of both fish oil and krill oil, could lead to potential side effects. The FDA suggests a maximum amount of combined EPA and DHA daily from supplements.

Excessive intake can potentially:

Increase the risk of bleeding, especially for those on blood-thinning medication.
Cause digestive issues like diarrhea, bloating, and upset stomach.
Raise LDL ("bad") cholesterol in some cases, particularly with higher DHA intake.

Medication interactions

Both fish oil and krill oil can affect blood clotting. Individuals taking anticoagulant or antiplatelet drugs, such as warfarin or aspirin, should consult a doctor before combining supplements, as it could increase the risk of bleeding. High doses of omega-3s may also affect blood pressure, so those on blood pressure medication should also seek medical advice.

Allergic reactions

Since krill are crustaceans, individuals with shellfish allergies should avoid krill oil entirely. Seafood allergies are also a consideration with fish oil, though the risk is lower with highly purified products.

Quality and purity

The supplement market is not strictly regulated by the FDA, so quality and purity can vary. Look for high-quality products that are third-party tested and certified by organizations like the Marine Stewardship Council (MSC) for sustainability and the International Fish Oil Standards Program (IFOS) for purity. This helps ensure the products are free from heavy metals and contaminants.

How to decide and proceed

Deciding whether to take fish oil and krill oil together depends on your specific health goals, budget, and individual response. Here's a guided approach:

Assess Your Goals: If you are looking for higher amounts of omega-3s for specific conditions, fish oil's higher concentration might be more practical and cost-effective. If you prioritize absorption, antioxidants, and a potentially more stomach-friendly option, adding krill oil may be beneficial.
Consult a Healthcare Professional: Before combining supplements, it is crucial to consult a doctor, especially if you have pre-existing health conditions or take other medications. They can provide personalized advice based on your health status and needs.
Start with One: If you are new to omega-3 supplements, start with either fish oil or krill oil first to see how your body responds. This makes it easier to identify any side effects that may arise.
Consider a Combination Product: Some supplement manufacturers offer combined fish and krill oil products, which simplifies the process and provides a pre-formulated synergistic blend. This can be a convenient way to get the benefits of both.
Prioritize Your Diet: Remember that supplements are intended to complement a healthy diet, not replace it. The best way to get omega-3s is by eating fatty fish at least twice a week. Food sources provide additional nutrients that supplements don't.

Conclusion

In conclusion, it is generally safe for most people to take fish oil and krill oil together, and doing so can provide a comprehensive and synergistic omega-3 profile. The combination can leverage fish oil's higher EPA and DHA content and krill oil's enhanced bioavailability and antioxidant properties. However, it is essential to consider the potential risks of excessive intake, medication interactions, and allergies. Consulting with a healthcare provider is the most responsible way to determine the right approach for your individual health needs. For optimal results, prioritize whole-food sources of omega-3s and use supplements as a complement to a balanced diet and healthy lifestyle.

Frequently Asked Questions

Taking fish oil and krill oil simultaneously is generally safe for most healthy people. The combination can provide a more comprehensive omega-3 profile, with the higher concentration from fish oil and the enhanced absorption from krill oil.

There is no definitive answer, as both have different strengths. Krill oil offers better absorption due to its phospholipid form and contains astaxanthin, a powerful antioxidant. Fish oil, however, typically provides a higher concentration of EPA and DHA per serving and is backed by decades of research. Some studies suggest krill oil may be more effective at improving certain heart disease risk factors, but more research is needed.

Side effects are usually mild and may include digestive upset such as nausea, diarrhea, heartburn, or burping. The risk of side effects, including a higher risk of bleeding, increases with excessive intake.

No, if you have a shellfish allergy, you should not take krill oil. Krill are crustaceans, and the oil can trigger an allergic reaction.

According to the FDA, there is a recommended upper limit for daily intake of combined EPA and DHA from supplements. Always consult with a doctor to determine the appropriate amount for your individual needs.

It is not necessary for most people, as eating fatty fish twice a week can provide adequate omega-3s. Supplements are intended to complement a diet, not replace it. If you have specific health conditions, consult a doctor to see if supplementation is warranted.

Krill harvesting is often considered more sustainable because krill are an abundant species low on the food chain. However, sustainability varies by brand, so look for third-party certifications like the Marine Stewardship Council (MSC) for assurance.