Herb & supplement monograph

Cod Liver Oil Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Cod Liver Oil interacts with medications. The heart of this page is the interaction list — every drug Cod Liver Oil is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Cod Liver Oil is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Cod Liver Oil Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a serious Cod Liver Oil drug interaction appears low for most people, though a few medication groups call for some caution. None of the listed interactions are rated major, and most rest on theoretical concerns or effects seen only in limited situations.

Interactions deserving the most attention

The best-documented concern involves blood pressure medications, since cod liver oil can lower blood pressure on its own and may add to their effect. With anticoagulant or antiplatelet drugs, a higher bleeding risk is theoretical, based on very high daily doses that prolonged bleeding time in healthy volunteers. There is also a possible additive effect with diabetes medications, where research found lower blood sugar in women with gestational diabetes after at least 12 weeks of use, but no effect over shorter periods.

What the rest of the list means

The long list of interacting medications largely reflects these same three effects, on blood pressure, bleeding, and blood sugar, applied across many drugs. Most of these pairings are precautionary rather than proven, and some predicted effects, like the short-term blood sugar change, have not appeared in people.

Check your medications against Cod Liver Oil

Based on HelloPharmacist’s Cod Liver Oil interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Cod Liver Oil

375 medications have a known interaction with Cod Liver Oil, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Cod Liver Oil using our pharmacist-reviewed interaction data.

AI summaries are generated from our Cod Liver Oil interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Cod Liver Oil combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Cod Liver Oil affects

Every type of medication (drug category) Cod Liver Oil is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 3 drug categories Cod Liver Oil interacts with

Anticoagulant/antiplatelet DrugsAntidiabetes DrugsAntihypertensive Drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, cod liver oil may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
High doses of cod liver oil, 20-40 mL daily, have been associated with prolonged bleeding time and reduced platelet aggregation in healthy volunteers.

Likelihood Possible Evidence B

Antidiabetes Drugs

Theoretically, taking cod liver oil with antidiabetes drugs might increase the risk of hypoglycemia.
Some clinical research shows that cod liver oil may lower blood glucose levels in women with gestational diabetes who are already taking antidiabetes drugs when used for at least 12 weeks. However, it does not appear to have any effect on blood glucose when used for shorter durations. Until more is known, use caution.

Likelihood Possible Evidence A

Antihypertensive Drugs

Theoretically, taking cod liver oil with antihypertensive drugs might increase the risk of hypotension.
Cod liver oil can lower blood pressure and might have additive effects in patients treated with antihypertensives; use with caution.

Likelihood Probable Evidence B

Monograph

Cod Liver Oil: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Cod liver oil supplies omega-3 fatty acids (EPA and DHA) along with vitamins A and D, and is popular for heart, joint, and general health support. Evidence is strongest for its nutrient content, but proof of specific disease benefits is mixed. Because it contains vitamin A, taking too much can be harmful, so check with your pharmacist or doctor before using it.

Part used: Liver of the Atlantic cod fish
Common forms: Liquid oil, softgel capsules, flavored emulsions

People commonly use it for

Source of omega-3 fatty acids
Vitamin A and D supplementation
Heart health
Joint and bone health
Reducing inflammation

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated, but its vitamin A content means high doses can be harmful over time.

PregnancyPossibly Safe

When used orally and appropriately in doses providing no more than the recommended dietary allowances (RDAs) of vitamins A and D. For vitamin A, the R...

Read the full pregnancy detail

BreastfeedingPossibly Safe

When used orally and appropriately in doses providing no more than the recommended dietary allowances (RDAs) of vitamins A and D. For vitamin A, the R...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Cod liver oil is an oil pressed from the liver of the Atlantic cod, a fish found in the cold waters of the North Atlantic Ocean. It has been used for generations as a traditional health tonic, especially in northern Europe.

Unlike regular fish oil, which comes from the body tissue of oily fish, cod liver oil comes from the liver. This gives it two extra nutrients in meaningful amounts: vitamin A and vitamin D. Like fish oil, it also provides the omega-3 fatty acids EPA and DHA.

Today it is sold as a liquid (sometimes flavored to hide the fishy taste) and as softgel capsules. People take it to support heart, joint, and bone health and to add omega-3s and vitamins to their diet.

How it works

Cod liver oil contains several active components. The omega-3 fatty acids EPA and DHA are thought to help reduce the body's production of certain inflammatory substances and may affect blood fats like triglycerides. Much of this understanding comes from laboratory and population research.

Vitamin A supports vision, skin, and immune function, while vitamin D helps the body absorb calcium and supports bones and the immune system.

Because the oil delivers these nutrients together, its effects are a combination of the omega-3s and the fat-soluble vitamins rather than from any single ingredient.

Effectiveness

Does Cod Liver Oil work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 27 uses evaluated

1 Leans ineffective 26 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Ineffective Coronavirus disease 2019 (COVID-19)