What vitamins should you not take with omega-3?

Studies have shown that omega-3 fatty acids can reduce inflammation and support heart health, but combining them with certain vitamins requires caution to avoid potential complications. Navigating these combinations safely is crucial for maximizing benefits and preventing adverse effects that can arise from nutrient interactions.

Quick Summary

Taking omega-3 supplements alongside specific vitamins, particularly fat-soluble ones like A and D from cod liver oil, can lead to over-supplementation risks. Users should carefully review supplement labels and dosages to prevent potential interactions and toxicity.

Key Points

• Cod Liver Oil and Vitamin A Toxicity: Combining cod liver oil, which is high in vitamin A, with another multivitamin can lead to unsafe, toxic levels of this fat-soluble vitamin.

• High-Dose Vitamin E and Bleeding Risk: While often combined safely, taking very high doses of both omega-3 and vitamin E could increase bleeding risk, especially for those on blood thinners.

• Avoid Overlapping Fat-Soluble Vitamins: The biggest danger is unintentionally doubling up on fat-soluble vitamins (A, D, E, K), which can accumulate in the body. Always check labels to prevent overdose.

• Separate Orlistat and Omega-3 Doses: The weight-loss drug Orlistat blocks fat absorption, diminishing the effectiveness of omega-3s. Take supplements and the medication at least two hours apart.

• Consult a Doctor for Medications: Omega-3s can interact with prescription medications, including blood thinners and blood pressure drugs. It is crucial to consult a healthcare provider before combining them.

Understanding Omega-3s and Vitamin Interactions

Omega-3 fatty acids, including EPA and DHA, are celebrated for their wide range of health benefits, from supporting cardiovascular and cognitive function to reducing inflammation. For most people, taking omega-3 supplements alongside a standard multivitamin is safe and even complementary. The healthy fats in omega-3s can actually help improve the absorption of fat-soluble vitamins (A, D, E, and K), which is an added bonus. However, the risk arises when dealing with specific types of supplements or very high doses, leading to potential interactions that could be detrimental.

The Specific Concern: Cod Liver Oil

Not all omega-3 supplements are created equal. While many fish oil supplements focus solely on EPA and DHA, cod liver oil is a distinct product sourced from the liver of codfish. As a result, it is naturally rich in fat-soluble vitamins A and D. This is the most important interaction to be aware of when adding other supplements to your routine.

Taking a cod liver oil supplement alongside a separate multivitamin can easily lead to excessive intake of vitamins A and D. The body stores fat-soluble vitamins, and overconsumption can result in toxicity. Vitamin A toxicity, for instance, can cause a range of symptoms from dizziness and nausea to liver damage over time. To mitigate this risk, individuals taking cod liver oil should be vigilant about checking the vitamin A and D content in all other supplements they consume.

High-Dose Vitamin E and Bleeding Risk

Vitamin E is a potent antioxidant often co-formulated in fish oil supplements to protect the omega-3 fatty acids from oxidation. For this reason, standard doses are considered beneficial when taken together. However, both omega-3s and high-dose vitamin E have anticoagulant (blood-thinning) properties. While interactions are not universally found at typical doses, taking very high doses of both could theoretically increase the risk of bleeding, especially for individuals with bleeding disorders or those taking blood-thinning medications. It is always recommended to consult a healthcare professional before combining high-dose supplements.

Medications That Interact with Omega-3s

Beyond vitamins, several non-vitamin supplements and medications have known interactions with omega-3 fatty acids. While this article focuses on vitamins, it is prudent to be aware of these other common interactions for overall safety.

• Anticoagulants and Antiplatelet Drugs: Omega-3s can have a mild blood-thinning effect, which can be amplified when taken with anticoagulant drugs like warfarin, heparin, or antiplatelet drugs like aspirin. This increases the risk of excessive bleeding.
• Blood Pressure Medications: High-dose omega-3s may slightly lower blood pressure. When combined with prescription blood pressure medications (e.g., ACE inhibitors, beta-blockers), this could cause blood pressure to drop too low.
• Orlistat: This weight-loss medication works by blocking fat absorption. Since omega-3s are fats, Orlistat can interfere with their absorption and diminish their effectiveness. The recommendation is to take the supplements and medication at least two hours apart.

Considerations for Safe Supplementation

To ensure you are combining your supplements safely, follow these guidelines:

• Read Labels Carefully: Scrutinize the nutrient facts on all your supplements. A multivitamin and cod liver oil are likely to overlap significantly in vitamins A and D content.
• Choose Standard Fish Oil: If you take a multivitamin, consider choosing a standard fish oil supplement that is not also high in vitamins A and D to avoid accidental overconsumption.
• Time Your Doses: For supplements that interfere with absorption, like Orlistat, separate your doses by a few hours as advised. For fat-soluble vitamins and omega-3s, taking them with a fat-containing meal improves absorption for both.
• Consult a Professional: If you are on prescription medication or have underlying health conditions, always talk to your doctor or a registered dietitian before starting a new supplement routine.

Comparison of Common Omega-3 Sources

Feature	Standard Fish Oil	Cod Liver Oil	Comments
Omega-3 Content	Contains EPA and DHA. The amount varies by product.	Contains EPA and DHA. The amount varies by product.	Primary source of beneficial fatty acids.
Vitamin A	Not typically present, or in negligible amounts.	Naturally high in Vitamin A.	Combining with a multivitamin can cause Vitamin A toxicity.
Vitamin D	Not typically present, or in negligible amounts.	Naturally high in Vitamin D.	Combining with another vitamin D supplement can cause over-supplementation.
Overlapping Nutrients	Safe to combine with a multivitamin in most cases.	High risk of duplicating fat-soluble vitamins from a multivitamin.
Best for	A general daily supplement of EPA/DHA without extra fat-soluble vitamins.	For those specifically looking for a natural source of vitamins A and D in addition to omega-3s, but must be cautious of other supplements.

Conclusion

While omega-3s are generally safe and compatible with many other vitamins, specific risks exist with certain product types and high dosages. The most significant interaction to avoid is the double-dosing of fat-soluble vitamins, particularly vitamins A and D, which is common when combining cod liver oil with a multivitamin. By being an informed consumer, carefully checking product labels, and consulting a healthcare provider, you can safely integrate omega-3s and other supplements into your wellness routine. For more information on the safety of supplements, consult authoritative sources like the National Institutes of Health.(https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/)

Potential Interactions to Consider

• High-Dose Vitamin E: When taken in high doses alongside omega-3s, there's a theoretical risk of increased bleeding due to their combined anticoagulant effects.
• Vitamin A from Cod Liver Oil: Combining cod liver oil, which is high in vitamin A, with a multivitamin containing vitamin A can lead to toxic levels of this fat-soluble vitamin.
• Orlistat (Weight-Loss Drug): This medication blocks fat absorption, which can prevent the proper absorption of omega-3s and other fat-soluble vitamins. Dosing should be separated by at least two hours.
• Vitamin K (Indirectly): While omega-3s and vitamin K are typically synergistic for bone health, cod liver oil's vitamin A and D content can be a factor to monitor when combining it with a vitamin K supplement.
• Blood-Thinning Medications: Omega-3s can have a mild blood-thinning effect, so combining them with anticoagulants or antiplatelet drugs requires careful medical supervision due to increased bleeding risk.
• Blood Pressure Medications: Omega-3s can slightly lower blood pressure. Taking them with prescription blood pressure medication could cause an excessive drop in blood pressure.
• Multiple Fat-Soluble Supplements: Caution is always advised when taking more than one source of fat-soluble vitamins (A, D, E, K), as they can accumulate in the body and become toxic.

FAQ

What is the main vitamin interaction concern with omega-3s? The main concern is over-supplementation with fat-soluble vitamins, especially Vitamin A, when combining a cod liver oil supplement with a multivitamin.

Can I take a multivitamin and a standard fish oil supplement together? Yes, for most people, it is generally safe to combine a standard multivitamin with a fish oil supplement, as they offer complementary benefits and do not typically contain overlapping fat-soluble vitamins.

Why should I be cautious about taking cod liver oil with a multivitamin? Cod liver oil is naturally high in vitamins A and D. Taking it with a multivitamin that also contains these vitamins can lead to an unsafe intake, potentially causing vitamin A toxicity.

How can I avoid vitamin A toxicity from supplements? To avoid vitamin A toxicity, check the labels of all your supplements. If you take a cod liver oil product, ensure your other supplements do not contain significant additional amounts of vitamin A.

Is it ever safe to take omega-3s with vitamin E? Yes, in most cases. Vitamin E is often added to omega-3 supplements as an antioxidant. The concern only arises with very high doses of both, which could increase bleeding risk, especially if you have pre-existing bleeding issues or are on blood-thinning medication.

Do omega-3s affect vitamin K? Omega-3s can actually help with the absorption of vitamin K, as it is a fat-soluble vitamin. There is no known direct negative interaction, but the overall intake of all fat-soluble vitamins should be monitored.

What should I do if I take blood-thinning medication? If you take any anticoagulant or antiplatelet medication, you should consult with your doctor before taking omega-3 supplements, as they can have a blood-thinning effect that increases the risk of bleeding.

Citations

• Mayo Clinic. (2024). Fish oil. Retrieved from https://www.mayoclinic.org/drugs-supplements-fish-oil/art-20364810
• Healthline. (2025). 9 Little-Known Side Effects of Too Much Fish Oil. Retrieved from https://www.healthline.com/nutrition/fish-oil-side-effects
• Beastlife. (2025). Can I Take Multivitamin and Fish Oil Together? Retrieved from https://beastlife.in/blogs/blog/can-i-take-multivitamin-and-fish-oil-together
• Drugs.com. (2025). Omega-3 Interactions Checker. Retrieved from https://www.drugs.com/drug-interactions/omega-3-polyunsaturated-fatty-acids,omega-3.html
• EatingWell. (2025). 4 Medications Your Omega-3 Supplement May Interact With. Retrieved from https://www.eatingwell.com/medications-your-omega-3-supplement-may-interact-with-11806262
• WebMD. (2025). Fish Oil: Uses, Side Effects and More. Retrieved from https://www.webmd.com/vitamins/ai/ingredientmono-993/fish-oil
• Carlson Labs. (2022). Omega-3 + D & K: The Perfect Combination of Nutrients. Retrieved from https://www.carlsonlabs.com/blogs/omega-3s-supplements/omega3-d-k-the-perfect-combination-of-nutrients
• OmegaQuant. (2022). New Research: Omega-3s and B vitamins – Better Together for the Heart. Retrieved from https://omegaquant.com/new-research-omega-3s-and-b-vitamins-better-together-for-the-heart/
• La Boîte à Grains. (2024). When to Take Omega-3 Supplements for Maximum Benefits. Retrieved from https://laboiteagrains.com/en/blogs/overall-health/when-take-omega3-supplements
• Drugs.com. (2025). Omega-3 and vitamin e Interactions Checker. Retrieved from https://www.drugs.com/drug-interactions/omega-3-with-vitamin-e-1749-15695-2306-0.html
• The 'Pause Blog. (2024). Omega-3, Vitamin D3 & K2: Partners In Health. Retrieved from https://thepauselife.com/blogs/the-pause-blog/omega-3-vitamin-d3-k2-partners-in-health
• NDL Pro-Health. (2025). Can Omega-3 and Vitamin E be taken together?. Retrieved from https://ndlprohealth.com/en-us/blogs/tips/can-omega-3-and-vitamin-e-be-taken-together

Frequently Asked Questions

Can I take cod liver oil with a multivitamin?

You should be very cautious about combining cod liver oil with a multivitamin. Cod liver oil is naturally high in vitamins A and D, and taking both supplements can easily lead to a toxic intake of these fat-soluble vitamins.

Is it safe to take a standard fish oil supplement with my daily multivitamin?

Yes, for most people, it is safe to take a standard fish oil supplement alongside a daily multivitamin. Standard fish oil is typically purified and does not contain significant amounts of added fat-soluble vitamins, reducing the risk of over-supplementation.

Does omega-3 interact with vitamin E?

At standard doses, vitamin E is often added to fish oil to prevent oxidation and is considered safe. However, taking very high doses of both supplements can theoretically increase the risk of bleeding due to their combined blood-thinning effects.

What is the risk of over-supplementing fat-soluble vitamins?

Unlike water-soluble vitamins, fat-soluble vitamins (A, D, E, K) are stored in the body. Taking excessive amounts over time can lead to a buildup that becomes toxic, causing adverse health effects.

How can I check for potential vitamin interactions with my supplements?

Always read the supplement facts labels carefully to see the precise ingredients and dosages. Pay special attention to the content of fat-soluble vitamins (A, D, E, K) across all products to avoid unintentional duplication.

Should I take omega-3s with food?

Yes, omega-3 supplements are best taken with a meal containing some dietary fat. This improves the absorption of the omega-3 fatty acids and other fat-soluble vitamins that may be present.

Can omega-3s affect blood pressure medication?

Yes, high-dose omega-3s can have a mild blood pressure-lowering effect. Combining them with prescription blood pressure medication could cause your blood pressure to drop too low, so a doctor's consultation is necessary.

Do omega-3 supplements interfere with the weight-loss drug Orlistat?

Yes, Orlistat can decrease the absorption of fats, including omega-3 fatty acids. To prevent this, you should take your omega-3 supplement at least two hours apart from the Orlistat dose.