Major interaction on record — check this product against your medications before combining. Check your meds →
Dietary supplement

Cod Liver Oil 1000 mg - Extra Strength Ingredients & Drug Interactions

by NOW

Cod Liver Oil 1000 mg - Extra Strength label
See full label image
Softgel Capsule Category: Fat/fatty Acid
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Cod Liver Oil 1000 mg - Extra Strength against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

Cod Liver Oil 1000 mg - Extra Strength is a dietary supplement by NOW with 3 active ingredients. Its ingredients are commonly taken for bone health and osteoporosis, correcting vitamin d deficiency, immune system support.Based on those ingredients, 1,170 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Vitamin D3, Vitamin A, Cod Liver Oil. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Cod Liver Oil 1000 mg - Extra Strength by NOW

Ask about any prescription or over-the-counter medication and we check it for interactions with Cod Liver Oil 1000 mg - Extra Strength by NOW — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of Cod Liver Oil 1000 mg - Extra Strength by NOW

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 4 of its 4 active ingredients.
  • “Cod Liver Oil” is listed as a grouped ingredient — the label gives one combined amount (1 Gram(s)) without saying how much of each component you get.

This product contains 4 active ingredients: vitamin A, vitamin D3, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Vitamin D3 helps your body absorb calcium and maintain bone health; vitamin A supports vision and immune function.

EPA and DHA are omega-3 fatty acids sourced from cod liver oil, traditionally used to support heart and brain health. The product also contains inactive ingredients (bovine gelatin, glycerin, and water) as the capsule and base.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Moderate

Some clinical evidence supports this product's ingredients for its stated purpose, but it isn't conclusive.

Why this rating?
  • The label markets this product for: Omega-3 fatty acids for heart health.
  • We looked for evidence on: Coronary heart disease (CHD), Cardiovascular disease (CVD), Arrhythmia, Atrial fibrillation, Heart failure, Hyperlipidemia — and 3 related terms.
  • The strongest evidence on file: Vitamin D is rated "Possibly Effective" for Heart failure (Natural Medicines).
  • Also on file: Vitamin D is rated "Possibly Ineffective" for Cardiovascular disease (CVD).
  • Also on file: Vitamin D is rated "Insufficient Reliable Evidence To Rate" for Atrial fibrillation, Hyperlipidemia.

Vitamin D3 is effective for treating rickets, osteomalacia (soft bones from vitamin D deficiency), renal bone disease, and low blood phosphate disorders. Vitamin A is effective for vitamin A deficiency; it's possibly effective for aging skin, oral leukoplakia (precancerous mouth lesions), measles, inflammatory bowel disease, and a rare lung condition in premature infants.

The evidence we hold does not establish effectiveness ratings for the omega-3 fatty acids in this product (EPA and DHA).

The evidence, ingredient by ingredient Vitamin D Cod Liver Oil Vitamin A

How safe is it?

Well-documented data
Safety Information · database check
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Vitamin D3 is generally well tolerated at recommended doses, but very high doses taken over time can cause vitamin D toxicity with symptoms of high blood calcium (hypercalcemia), kidney problems, and anemia. Vitamin A is generally safe at recommended amounts but can be toxic at high doses because it builds up in your body over time.

Serious side effects from either vitamin are rare but can include liver damage, bone loss (paradoxically), and in children, headache and brain swelling. At recommended dietary and supplement doses, both vitamins are acceptable during pregnancy and breastfeeding, though you should confirm dosing with your doctor.

Avoid high-dose supplements of either unless a clinician directs you.

Side effects, ingredient by ingredient Vitamin D Cod Liver Oil Vitamin A

Meds to double-check

Major interaction found
Known Interaction Concern · database check
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 2 of the 2 matched ingredients can interact with medications — Vitamin D, Vitamin A.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; heart-rhythm medications.
  • For scale: 946 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.

Check these medication types before taking this product: retinoids (acne medications), followed by thiazide water pills and calcium-channel blockers (verapamil, diltiazem), atorvastatin (cholesterol), digoxin (heart rhythm), warfarin (blood thinner), tetracycline antibiotics, and any other potentially liver-damaging drugs. Also mention if you take any CYP3A4 substrate medications—your pharmacist can help identify them.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with some supporting evidence for its stated purpose. Major medication interactions have been identified, and safety information is well characterized.

This is a straightforward omega-3 and vitamin supplement, but it does interact with several common medications—especially acne drugs, heart medications, blood thinners, and antibiotics. If you take any prescription medications, check them against the interaction tool below before you start.

Talk with your pharmacist or doctor about whether this product and your current doses are a good fit together.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 2 of 4 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Jun 20, 2024.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Cod Liver Oil 1000 mg - Extra Strength, straight from the product label.

Brand NOW
Barcode (UPC) 733739017444
Net contents 180 Softgel(s)
Market status On market
Date entered into DSLD Jun 20, 2024
DSLD ID 314108
Product type Fat/fatty Acid
Supplement form Softgel Capsule
Dietary claims / uses Nutrient, All Other, Qualified Health, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Kosher, Halal, Gluten Free, Dairy Free
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Cod Liver Oil 1000 mg - Extra Strength by NOW, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Softgel(s)
Maximum serving Sizes:
1 Softgel(s)
Servings per container
180
UPC/BARCODE
733739017444
IngredientAmount% DV
Calories10 Calorie(s)--
Eicosapentaenoic Acid70 mg--
Docosahexaenoic Acid100 mg--
Total Fat1 Gram(s)1%
Vitamin D310 mcg50%
Cod Liver Oil1 Gram(s)--
Vitamin A300 mcg33%

Other ingredients: Bovine Gelatin, Glycerin, Water

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Suggested/Recommended/Usage/Directions

Suggested Usage: Take 1 softgel daily with a meal.

Formulation

Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.

The natural cod liver oil used in this softgel is manufactured under strict quality control standards. It is tested to be free of potentially harmful levels of contaminants such as PCB’s, dioxins, mercury and other heavy metals.

Natural color variation may occur in this product.

Cardiovascular Support

Non-GMO

Packaged and quality tested in the USA. Cod Liver Oil is product of Iceland, Norway.

Not manufactured with wheat, gluten, soy, corn, milk, egg, shellfish or sesame ingredients.

EUA # 1482865

Formula

NOW Cod Liver Oil abounds in Omega-3 Fatty Acids, EPA (Eicosapentaenoic Acid) and DHA (Docosahexaenoic Acid). It is also an excellent source of Vitamins A and D-3. Cod Liver Oil has a long history of traditional use for the support of overall health and well-being.

Crescent H (Halal)

Vitamins A & D-3, EPA, DHA

Triangle K (Kosher) Contains Gelatin

This extra strength product has more cod liver oil (1,000 mg per softgel) than our cod liver oil 650 mg softgel product.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

Precautions

Caution: For adults only. Keep out of reach of children.

Consult physician if pregnant/nursing, taking medication, or have a medical condition.

Triangle K (Kosher) Contains Gelatin

Contains fish (cod).

Not manufactured with wheat, gluten, soy, corn, milk, egg, shellfish or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.

Storage

Store in a cool, dry place after opening.

General Statements

This bottle is made from 100% PCR (post-consumer recycled) resin.

Omega-3/Fish Oils Family owned since 1968.

Seals/Symbols

Crescent H (Halal) GMP Quality Assured

Triangle K (Kosher) Contains Gelatin

FDA Statement of Identity

A Dietary Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Cod Liver Oil 1000 mg - Extra Strength by NOW label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Cod Liver Oil 1000 mg - Extra Strength label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Cod Liver Oil 1000 mg - Extra Strength by NOW

These are the 3 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Softgel(s) Dosage formSoftgel Capsule Servings per container180 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Vitamin D3

Interacts with
715 drugs
10 mcg per serving Form: Cholecalciferol, Cod Liver Oil

Vitamin D is a fat-soluble vitamin that helps your body absorb calcium and is important for healthy bones, muscles, and immune function. Many people,...

Vitamin D3 monograph & interactions

Cod Liver Oil

Interacts with
375 drugs
1 Gram(s) per serving

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. Evi...

Cod Liver Oil monograph & interactions
  • › Eicosapentaenoic Acid
  • › Docosahexaenoic Acid

Vitamin A

Interacts with
387 drugs
300 mcg per serving Form: Cod Liver Oil, Retinyl Palmitate

Vitamin A is an essential nutrient important for vision, skin, immune function, and growth. Most people get enough from a balanced diet, and supplemen...

Vitamin A monograph & interactions

Other (inactive) ingredients: Bovine Gelatin, Glycerin, Water. These complete the product’s ingredient list but are not active constituents.

Interaction report

Cod Liver Oil 1000 mg - Extra Strength by NOW Drug Interactions

Want to check YOUR meds against Cod Liver Oil 1000 mg - Extra Strength?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
1,170Drugs
9 Major 724 Moderate 437 Minor

Ingredients driving the most interactions

Vitamin D3 715
Vitamin A 387
Cod Liver Oil 375

Individual Drug Interactions

The ingredients in Cod Liver Oil 1000 mg - Extra Strength interact with 1,170 drugs. Click any drug to see the details.

3 of the 3 ingredients in Cod Liver Oil 1000 mg - Extra Strength interact with drugs. Each result below shows which ingredient is responsible. Vitamin D3 Vitamin A Cod Liver Oil

Each ingredient & the kinds of drugs it affects

For each ingredient in Cod Liver Oil 1000 mg - Extra Strength with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Vitamin D38 drug types · 715 drugs

Aluminum

Vitamin D might increase aluminum absorption and toxicity, but this has only been reported in people with renal failure.
The protein that transports calcium across the intestinal wall can also bind and transport aluminum. This protein is stimulated by vitamin D, which may therefore increase aluminum absorption. This mechanism may contribute to increased aluminum levels and toxicity in people with renal failure, when they take vitamin D and aluminum-containing phosphate binders chronically.

Likelihood Probable Evidence B
Atorvastatin (Lipitor)

Vitamin D might reduce absorption of atorvastatin.
A small, low-quality clinical study shows that taking vitamin D reduces levels of atorvastatin and its active metabolites by up to 55%. However, while atorvastatin levels decreased, total cholesterol, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol levels did not substantially change. Atorvastatin is metabolized in the gut by CYP3A4 enzymes, and researchers theorized that vitamin D might induce CYP3A4, causing reduced levels of atorvastatin. However, this proposed mechanism was not specifically studied.

Likelihood Probable Evidence B
Calcipotriene (Dovonex)

Taking calcipotriene with vitamin D increases the risk for hypercalcemia.
Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia. Theoretically, combining calcipotriene with vitamin D supplements might increase the risk of hypercalcemia.

Likelihood Probable Evidence D
Digoxin (Lanoxin)

Theoretically, hypercalcemia induced by high-dose vitamin D can increase the risk of arrhythmia from digoxin.
High doses of vitamin D can cause hypercalcemia. Hypercalcemia increases the risk of fatal cardiac arrhythmias with digoxin. Avoid vitamin D doses above the tolerable upper intake level (4000 IU daily for adults) and monitor serum calcium levels in people taking vitamin D and digoxin concurrently.

Likelihood Possible Evidence D
Diltiazem (Cardizem, Others)

Theoretically, hypercalcemia induced by high-dose vitamin D can reduce the therapeutic effects of diltiazem for arrhythmia.
High doses of vitamin D can cause hypercalcemia. Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation. Theoretically this could also occur with diltiazem. Avoid vitamin D doses above the tolerable upper intake level (4000 IU daily for adults) and monitor serum calcium levels in people taking vitamin D and diltiazem concurrently.

Likelihood Probable Evidence B
Thiazide Diuretics

Theoretically, taking thiazide diuretics and high-dose vitamin D can increase the risk of hypercalcemia.
Thiazide diuretics decrease urinary calcium excretion, which could lead to hypercalcemia if vitamin D supplements are taken concurrently. This has been reported in people being treated with vitamin D for hypoparathyroidism, and also in elderly people with normal parathyroid function who were taking a thiazide, vitamin D, and calcium-containing antacids daily.

Likelihood Probable Evidence D
Verapamil (Calan, Others)

Hypercalcemia induced by high-dose vitamin D can reduce the therapeutic effects of verapamil for arrhythmia.
Hypercalcemia due to high doses of vitamin D can reduce the effectiveness of verapamil in atrial fibrillation. Avoid vitamin D doses above the tolerable upper intake level (4000 IU daily for adults) and monitor serum calcium levels in people taking vitamin D and verapamil concurrently.

Likelihood Probable Evidence B
Cytochrome P450 3A4 (Cyp3A4) Substrates

Vitamin D might induce CYP3A4 enzymes and reduce the bioavailability of CYP3A4 substrates.
There is some concern that vitamin D might induce CYP3A4. In vitro research suggests that vitamin D induces CYP3A4 transcription. Additionally, observational research has found that increased UV light exposure and serum vitamin D levels are associated with decreased serum levels of CYP3A4 substrates such as tacrolimus and sirolimus, while no association between UV light exposure or vitamin D levels and levels of mycophenolic acid, a non-CYP3A4 substrate, was found. A small, low-quality clinical study shows that taking vitamin D reduces levels of the CYP3A4 substrate atorvastatin and its active metabolites by up to 55%; however, the clinical effects of atorvastatin were not reduced. While researchers theorized that vitamin D might induce CYP3A4, this proposed mechanism was not specifically studied.

Likelihood Possible Evidence D
Vitamin D3 full monograph & interactions

Vitamin A4 drug types · 387 drugs

Retinoids

Concomitant use of retinoids with vitamin A supplements might produce supratherapeutic vitamin A levels.
Retinoids, which are vitamin A derivatives, could have additive toxic effects when taken with vitamin A supplements.

Likelihood Probable Evidence D
Hepatotoxic Drugs

Theoretically, taking high doses of vitamin A in combination with other potentially hepatotoxic drugs might increase the risk of liver disease.
The tolerable upper intake level (UL) is the highest level of intake that is likely to pose no risk of adverse effects. Doses of vitamin A above the UL can cause hepatotoxicity, ranging from elevated liver enzymes to liver failure.

Likelihood Possible Evidence C
Tetracycline Antibiotics

Theoretically, taking tetracycline antibiotics with high doses of vitamin A can increase the risk of pseudotumor cerebri.
Benign intracranial hypertension (pseudotumor cerebri) can occur with tetracyclines and with acute or chronic vitamin A toxicity. Case reports suggest that taking tetracyclines and vitamin A concurrently can increase the risk of this condition. Avoid high doses of vitamin A in people taking tetracyclines chronically.

Likelihood Possible Evidence D
Warfarin (Coumadin)

Theoretically, high doses of vitamin A could increase the risk of bleeding with warfarin.
Vitamin A toxicity is associated with hemorrhage and hypoprothrombinemia, possibly due to vitamin K antagonism. Advise patients taking warfarin to avoid doses of vitamin A above the tolerable upper intake level of 10,000 IU/day for adults.

Likelihood Possible Evidence D
Vitamin A full monograph & interactions

Cod Liver Oil3 drug types · 375 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
Cod Liver Oil full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Cod Liver Oil 1000 mg - Extra Strength, from the product label.

NOW

See all NOW products
Name
NOW Foods
Street Address
395 S. Glen Ellyn Rd.
City
Bloomingdale
State
IL
ZipCode
60108
Web Address
nowfoods.com
Pharmacist Counseling Corner

Cod Liver Oil 1000 mg - Extra Strength by NOW: Common Questions

Does Cod Liver Oil 1000 mg - Extra Strength by NOW interact with any medications?
Yes. Based on its ingredients, Cod Liver Oil 1000 mg - Extra Strength has a known interaction with 1,170 medications, including 9 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Cod Liver Oil 1000 mg - Extra Strength contains 3 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.
Can I take this if I'm pregnant or breastfeeding?
The safety data for vitamin D3 isn't clear in our records, so talk with your doctor before taking it during pregnancy or breastfeeding. Vitamin A has mixed safety ratings—recommended amounts are needed in pregnancy, but high doses (especially retinol) can cause birth defects. At the dose in this product, confirm with your doctor first.
What's the difference between the omega-3s in this—EPA and DHA?
EPA and DHA are both omega-3 fatty acids found in cod liver oil. Historically, cod liver oil has been used for general heart and brain health, but we don't hold established effectiveness ratings for these specific components in our data.
Will this cause vitamin A toxicity?
This product contains vitamin A at a supplement dose. Toxicity happens with very high doses taken over time—symptoms include skin peeling, hair loss, liver damage, and in rare cases, brain swelling. At recommended amounts, it's generally well tolerated, but avoid taking other high-dose vitamin A supplements or retinoid medications at the same time.
Does this product contain fillers?
Yes—the inactive ingredients are bovine gelatin (the capsule), glycerin, and water. These are standard excipients in softgel capsules.
Is vitamin D in this product high-dose?
That depends on the amount of vitamin D3 per serving, which isn't broken out in our product data. The safety threshold from our data is 4,000 IU daily for adults. Check the label for the exact dose per capsule and confirm with your pharmacist whether it's appropriate for you, especially if you take thiazide diuretics or heart medications.
What is vitamin A used for in the body?
Vitamin A supports vision, immune function, and skin health. We have data showing it's effective for vitamin A deficiency, and possibly effective for aging skin, certain mouth lesions, measles, and inflammatory bowel disease.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Not sure if Cod Liver Oil 1000 mg - Extra Strength is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Cod Liver Oil 1000 mg - Extra Strength label
Go deeper

The Full Monographs Behind Cod Liver Oil 1000 mg - Extra Strength’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Vitamin D

Interacts with 715 drugs

Vitamin D is a fat-soluble vitamin that helps your body absorb calcium and is important for healthy bones, muscles, and immune function. Many people, especially those with low sun exposure,...

Read the full Vitamin D monograph → Herb & supplement monograph

Cod Liver Oil

Interacts with 375 drugs

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 cont...

Read the full Cod Liver Oil monograph → Herb & supplement monograph

Vitamin A

Interacts with 387 drugs

Vitamin A is an essential nutrient important for vision, skin, immune function, and growth. Most people get enough from a balanced diet, and supplements are mainly useful for correcting a tr...

Read the full Vitamin A monograph →
Sources

Sources & How We Checked

Cod Liver Oil 1000 mg - Extra Strength's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 77 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Vitamin D 26 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Tatro DS, ed. Drug Interactions Facts. Facts and Comparisons Inc., St. Louis, MO. 1999.
  3. Koutkia P, Chen TC, Holick MF. Vitamin D intoxication associated with an over-the-counter supplement. N Engl J Med 2001;345:66-7. PubMed
  4. Bar-Or D, Yoel G. Calcium and calciferol antagonize effect of verapamil in atrial fibrillation. Br Med J 1981;282:1585-6.
  5. Demontis R, Leflon A, Fournier A, et al. 1 alpha(OH) vitamin D3 increases plasma aluminum in hemodialyzed patients taking AI(OH)3. Clin Nephrol 1986;26:146-9.
  6. Crowe M, Wollner L, Griffiths RA. Hypercalcemia following vitamin D and thiazide therapy in the elderly. Practitioner 1984;228:312-3.
  7. Parfitt AM. Thiazide-induced hypercalcemia in vitamin D-treated hypoparathyroidism. Ann Intern Med 1972;77:557-63. PubMed
  8. Thiazide diuretics and the risk of osteoporosis. Pharmacist's Letter/Prescriber's Letter 2003;19(11):191105.
  9. Moon J. The role of vitamin D in toxic metal absorption. J Am Coll Nutr 1994;13:559-64.
  10. Demontis R, Reissi D, Noel C, et al. Indirect clinical evidence that 1alphaOH vitamin D<SUB>3</SUB> increases the intestinal absorption of aluminum. Clin Nephrol 1989;31:123-7.
  11. Adler AJ, Berlyne GM. Duodenal aluminum absorption in the rat: effect of vitamin D. Am J Physiol 1985;249:G209-13. PubMed
  12. Schwartz JB. Effects of vitamin D supplementation in atorvastatin-treated patients: A new drug interaction with an unexpected consequence. Clin Pharmacol Ther 2009;85:198-203. PubMed
  13. Dietary reference intakes for calcium and vitamin D. Institute of Medicine, November 30, 2010. Available at: http://www.iom.edu/~/media/Files/Report%20Files/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Vitamin%20D%20and%20Calcium%202010%20Repo
  14. Cox KA, Dunn MA. Aluminum toxicity alters the regulation of calbindin-D28k protein and mRNA expression in chick intestine. J Nutr 2001;131:2007-13. PubMed
  15. Escribano, J., Balaguer, A., Pagone, F., Feliu, A., and Roque, I. Figuls. Pharmacological interventions for preventing complications in idiopathic hypercalciuria. Cochrane.Database.Syst.Rev. 2009;(1):CD004754. PubMed
  16. Carlton, S., Clopton, D., and Cappuzzo, K. A. Vitamin D deficiency: appropriate replenishment therapies and the effects of vitamin D toxicity. Consult Pharm 2010;25(3):171-177. PubMed
  17. Wang, H., Xia, N., Yang, Y., and Peng, D. Q. Influence of vitamin D supplementation on plasma lipid profiles: a meta-analysis of randomized controlled trials. Lipids Health Dis. 2012;11:42. PubMed
  18. Turner AN, Carr Reese P, Fields KS, Anderson J, Ervin M, Davis JA, Fichorova RN, Roberts MW, Klebanoff MA, Jackson RD. A blinded, randomized controlled trial of high-dose vitamin D supplementation to reduce recurrence of bacterial vaginosis. Am J Obstet G PubMed
  19. Weiner M, Epstein FH. Signs and symptoms of electrolyte disorders. Yale J Biol Med. 1970;43(2):76-109.
  20. Lappe J, Watson P, Travers-Gustafson D, Recker R, Garland C, Gorham E, Baggerly K, McDonnell SL. Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial. JAMA. 2017 Mar 28;317(12):1234-1243. PubMed
  21. Roth DE, Leung M, Mesfin E, Qamar H, Watterworth J, Papp E. Vitamin D supplementation during pregnancy: state of the evidence from a systematic review of randomised trials. BMJ. 2017;359:j5237. PubMed
  22. Murai IH, Fernandes AL, Sales LP, et al. Effect of a single high dose of vitamin D3 on hospital length of stay in patients with moderate to severe COVID-19: A randomized clinical trial. JAMA. 2021.
  23. Wang Z, Schuetz EG, Xu Y, Thummel KE. Interplay between vitamin D and the drug metabolizing enzyme CYP3A4. J Steroid Biochem Mol Biol 2013;136:54-8. PubMed
  24. Doyle D, Browne U, Brickley A, Murphy D. Vitamin D-induced hypercalcaemia and acute kidney injury in sarcoidosis. BMJ Case Rep 2023;16(1):e250580. PubMed
  25. Williamson A, Martineau AR, Sheikh A, Jolliffe D, Griffiths CJ. Vitamin D for the management of asthma. Cochrane Database Syst Rev 2023;2(2):CD011511. PubMed
  26. Kinesya E, Santoso D, Gde Arya N, et al. Vitamin D as adjuvant therapy for diabetic foot ulcers: Systematic review and meta-analysis approach. Clin Nutr ESPEN 2023;54:137-143. PubMed

See these in context on the Vitamin D monograph →

Cod Liver Oil 20 references
  1. Prisco D, Paniccia R, Bandinelli B, et al. Effect of medium-term supplementation with a moderate dose of n-3 polyunsaturated fatty acids on blood pressure in mild hypertensive patients. Thromb Res 1998;1:105-12.
  2. Toft I, Bonaa KH, Ingebretsen OC, et al. Effects of n-3 polyunsaturated fatty acids on glucose homeostasis and blood pressure in essential hypertension. A randomized, controlled trial. Ann Intern Med 1995;123:911-8.
  3. Dawson JK, Abernethy VE, Graham DR, Lynch MP. A woman who took cod-liver oil and smoked. Lancet 1996;347:1804. PubMed
  4. Stammers T, Sibbald B, Freeling P. Efficacy of cod liver oil as an adjunct to non-steroidal anti-inflammatory drug treatment in the management of osteoarthritis in general practice. Ann Rheum Dis 1992;51:128-9. PubMed
  5. Jensen T, Stender S, Goldstein K, et al. Partial normalization by dietary cod-liver oil of increased microvascular albumin leakage in patients with insulin-dependent diabetes and albuminuria. N Engl J Med 1989;321:1572-7. PubMed
  6. Brox JH, Killie JE, Gunnes S, Nordoy A. The effect of cod liver oil and corn oil on platelets and vessel wall in man. Thromb Haemost 1981;46:604-11. DOI
  7. Sanders TA, Vickers M, Haines AP. Effect on blood lipids and haemostasis of a supplement of cod-liver oil, rich in eicosapentainoic and docosahexaenoic acids, in healthy young men. Clin Sci (Colch) 1981;61:317-24.
  8. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  9. Brox JH, Killie JE, Osterud B, et al. Effects of cod liver oil on platelets and coagulation in familial hypercholesterolemia (type IIa). Acta Med Scand 1983;213:137-44.. PubMed
  10. Lorenz R, Spengler U, Fischer S, Duhm J, Weber PC. Platelet function, thromboxane formation and blood pressure control during supplementation of the Western diet with cod liver oil. Circulation 1983;67(3):504-11. PubMed
  11. Ahmed AA, Holub BJ. Alteration and recovery of bleeding times, platelet aggregation and fatty acid composition of individual phospholipids in platelets of human subjects receiving a supplement of cod-liver oil. Lipids 1984;19(8):617-24. PubMed
  12. Ross AC, Taylor CL, Yaktine AL, Del Valle HB (eds). Dietary reference intakes for calcium and vitamin D. Institute of Medicine, 2011. Available at: www.nap.edu/catalog/13050/dietary-reference-intakes-for-calcium-and-vitamin-d (accessed April 17, 2016). DOI
  13. Detopoulou P, Papamikos V. Gastrointestinal bleeding after high intake of omega-3 fatty acids, cortisone and antibiotic therapy: a case study. Int J Sport Nutr Exerc Metab 2014;24(3):253-7. PubMed
  14. Mai XM, Langhammer A, Chen Y, Camargo CA. Cod liver oil intake and incidence of asthma in Norwegian adults - the HUNT study. Thorax 2013;68(1):25-30. PubMed
  15. Gruenwald J, Graubaum HJ, Harde A. Effect of cod liver oil on symptoms of rheumatoid arthritis. Adv Ther 2002;19(2):101-7. PubMed
  16. Foti C, Bonamonte D, Conserva A, Pepe ML, Angelini G. Allergic contact dermatitis to cod liver oil contained in a topical ointment. Contact Dermatitis 2007;57(4):281-2. PubMed
  17. Helland IB, Saugstad OD, Saarem K, et al. Supplementation of n-3 fatty acids during pregnancy and lactation reduces maternal plasma lipid levels and provides DHA to the infants. J Matern Fetal Neonatal Med 2006;19(7):397-406. PubMed
  18. Olafsdottir AS, Thorsdottir I, Wagner KH, Elmadfa I. Polyunsaturated fatty acids in the diet and breast milk of lactating Icelandic women with traditional fish and cod liver oil consumption. Ann Nutr Metab 2006;50(3):270-6. PubMed
  19. Yang S, Lin R, Si L, et al. Cod-liver oil improves metabolic indices and hs-CRP levels in gestational diabetes mellitus patients: A double-blind randomized controlled trial. J Diabetes Res. 2019;2019:7074042. PubMed
  20. Conus N, Burgher-Kennedy N, van den Berg F, Kaur Datta G. A randomized trial comparing omega-3 fatty acid plasma levels after ingestion of emulsified and non-emulsified cod liver oil formulations. Curr Med Res Opin. 2019;35(4):587-593. PubMed

See these in context on the Cod Liver Oil monograph →

Vitamin A 31 references
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  2. Griffiths JK. The vitamin A paradox. J Pediatr 2000;137:604-7.. PubMed
  3. Hardman JG, Limbird LL, Molinoff PB, eds. Goodman and Gillman's The Pharmacological Basis of Therapeutics, 9th ed. New York, NY: McGraw-Hill, 1996.
  4. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  5. FDA Talk Paper. Vitamin A and birth defects (T95-56). Food and Drug Administration, U.S. Department of Health and Human Services, Rockville, MD. October 6, 1995.
  6. Russell RM. The vitamin A spectrum: from deficiency to toxicity. Am J Clin Nutr 2000;71:878-84. PubMed
  7. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  8. Feskanich D, Singh V, Willett WC, Colditz GA. Vitamin A intake and hip fractures among postmenopausal women. JAMA 2002;287:47-54. PubMed
  9. Melhus H, Michaelsson K, Kindmark A, et al. Excessive dietary intake of vitamin A is associated with reduced bone mineral density and increased risk for hip fracture. Ann Intern Med 1998;129:770-8. PubMed
  10. Michaelsson K, Lithell H, Vessby B, Melhus H. Serum retinol levels and the risk of fracture. N Engl J Med 2003;348:287-94.. PubMed
  11. Botterweck AA, van den Brandt PA, Goldbohm RA. Vitamins, carotenoids, dietary fiber, and the risk of gastric carcinoma: results from a prospective study after 6.3 years of follow-up. Cancer 2000;88:737-48.. DOI
  12. Meyskens FL Jr, Graham V, Chvapil M, et al. A phase I trial of beta-all-trans-retinoic acid delivered via a collagen sponge and a cervical cap for mild or moderate intraepithelial cervical neoplasia. J Natl Cancer Inst 1983;71:921-5..
  13. Hathcock JN, Hattan DG, Jenkins MY, et al. Evaluation of vitamin A toxicity. Am J Clin Nutr 1990;52:183-202.. PubMed
  14. Walters BN, Gubbay SS. Tetracycline and benign intracranial hypertension: report of five cases. Br Med J 1981;282:19-20.. PubMed
  15. Pearson MG, Littlewood SM, Bowden AN. Tetracycline and benign intracranial hypertension (letter). Br Med J 1981;282:568-9.. PubMed
  16. Azais-Braesco V, Pascal G. Vitamin A in pregnancy: requirements and safety limits. Am J Clin Nutr 2000;71:1325S-33S. PubMed
  17. Smedts HP, de Vries JH, Rakhshandehroo M, et al. High maternal vitamin E intake by diet or supplements is associated with congenital heart defects in the offspring. BJOG 2009;116:416-23. PubMed
  18. Grotto, I., Mimouni, M., Gdalevich, M., and Mimouni, D. Vitamin A supplementation and childhood morbidity from diarrhea and respiratory infections: a meta-analysis. J Pediatr 2003;142(3):297-304. PubMed
  19. Mahalanabis, D., Lahiri, M., Paul, D., Gupta, S., Gupta, A., Wahed, M. A., and Khaled, M. A. Randomized, double-blind, placebo-controlled clinical trial of the efficacy of treatment with zinc or vitamin A in infants and young children with severe acute l
  20. Long, K. Z., Montoya, Y., Hertzmark, E., Santos, J. I., and Rosado, J. L. A double-blind, randomized, clinical trial of the effect of vitamin A and zinc supplementation on diarrheal disease and respiratory tract infections in children in Mexico City, Mex
  21. Fritz, H., Kennedy, D., Fergusson, D., Fernandes, R., Doucette, S., Cooley, K., Seely, A., Sagar, S., Wong, R., and Seely, D. Vitamin A and retinoid derivatives for lung cancer: a systematic review and meta analysis. PLoS.One. 2011;6(6):e21107. PubMed
  22. Mayo-Wilson, E., Imdad, A., Herzer, K., Yakoob, M. Y., and Bhutta, Z. A. Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis. BMJ 2011;343:d5094. PubMed
  23. Mazumder S, Taneja S, Bhatia K, Yoshida S, Kaur J, Dube B, Toteja GS, Bahl R, Fontaine O, Martines J, Bhandari N; Neovita India Study Group. Efficacy of early neonatal supplementation with vitamin A to reduce mortality in infancy in Haryana, India (Neovit
  24. Baineni R, Gulati R, Delhi CK. Vitamin A toxicity presenting as bone pain. Arch Dis Child. 2017;102(6):556-8. PubMed
  25. Darlow BA, Graham PJ, Rojas-Reyes MX. Vitamin A supplementation to prevent mortality and short- and long-term morbidity in very low birth weight infants. Cochrane Database Syst Rev. 2016;(8):CD000501. PubMed
  26. Haider BA, Sharma R, Bhutta ZA. Neonatal vitamin A supplementation for the prevention of mortality and morbidity in term neonates in low and middle income countries. Cochrane Database Syst Rev. 2017;2:CD006980. PubMed
  27. Mohammad YM, Raslan IR, Al-Hussain FA. Idiopathic Intracranial Hypertension Induced by Topical Application of Vitamin A. J Neuroophthalmol. 2016;36(4):412-3. PubMed
  28. Masnadi Shirazi K, Nikniaz Z, Masnadi Shirazi A, Rohani M. Vitamin A supplementation decreases disease activity index in patients with ulcerative colitis: A randomized controlled clinical trial. Complement Ther Med. 2018 Dec;41:215-219. PubMed
  29. Ding Y, Hu P, Yang Y, et al. Impact of maternal daily oral low-dose vitamin A supplementation on the mother-infant pair: a randomised placebo-controlled trial in China. Nutrients 2021;13(7):2370. PubMed
  30. Knapik JJ, Hoedebecke SS. Vitamin A and bone fractures: systematic review and meta-analysis. J Spec Oper Med 2021;21(2):100-7. PubMed
  31. Imdad A, Mayo-Wilson E, Haykal MR, et al. Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age. Cochrane Database Syst Rev 2022;3(3):CD008524. PubMed

See these in context on the Vitamin A monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team