Drug & supplement interaction

Cod Liver Oil + Hydroxyurea

Hydroxyurea brand names: Droxia, Hydrea, Siklos, Xromi.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Cod Liver Oil and Hydroxyurea in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Cod Liver Oil and Hydroxyurea

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Hydroxyurea and Cod Liver Oil in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Cod Liver Oil safety at a glance

Cod Liver Oil overall Use caution Generally well tolerated, but its vitamin A content means high doses can be harmful over time.
Pregnancy Possibly 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 RDAs are 77... Read the full pregnancy detail
Breastfeeding Possibly 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 RDAs are 13... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Hydroxyurea and Cod Liver Oil? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Hydroxyurea

Interactions in our licensed database are recorded against drug classes, not just single drug names. Hydroxyurea is filed under 2 classifications — antineoplastics, oral drugs. Cod Liver Oil has documented interactions with 3 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate), antidiabetes drugs (moderate) and antihypertensive drugs (moderate) — and none of Hydroxyurea’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Cod Liver Oil Does Interact With Other Medications

Cod Liver Oil has 375 moderate known drug interactions in our database — Hydroxyurea isn’t one of them. If you take anything else, check it against the full list below.

Moderate 375 No known interaction 2,455 (incl. Hydroxyurea)
Taking anything else?

Check Another of Your Medications Against Cod Liver Oil

Covers the 2,830 medications we’ve checked against Cod Liver Oil. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Cod Liver Oil and Hydroxyurea May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 2 of them are worth acting on rather than waiting out — marked below.

  • Anemia Worth acting on reported in 12.0% of FDA reports for Hydroxyurea Additional detail

    Cod Liver Oil

    “Orally, there is a case report of melena, bleeding duodenal ulcer, and anemia in a 60 year old man who was taking cod liver oil 5 mL daily in combination with other supplements, including fish oil, flaxseed oil, chlorella, and sea buckthorn, which increased his intake of omega-3 fatty acids to more than 21 grams daily.”

    Cod Liver Oil · Natural Medicines adverse-effect record, reported in anemia.

    1 source cited
    1. 94751. 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

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • A higher chance of infection Worth acting on Additional detail

    Cod Liver Oil

    “Data from population surveys of adults in Norway conducted in the 1990s suggests that daily consumption of cod liver oil for at least a month is associated with a 1.6-fold increase in the odds of adult-onset asthma about 11 years later, when adjusted for several confounding factors.”

    Cod Liver Oil · Natural Medicines adverse-effect record, reported in asthma.

    2 sources cited
    1. 94752. 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
    2. 3396. Dawson JK, Abernethy VE, Graham DR, Lynch MP. A woman who took cod-liver oil and smoked. Lancet 1996;347:1804. PubMed

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea. Read the label on DailyMed ›

  • Diarrhea reported in 6.7% of FDA reports for Hydroxyurea Additional detail

    Cod Liver Oil

    “Orally, flatulence, heartburn, nausea, and gastrointestinal upset are the most frequently reported adverse effects of cod liver oil. Diarrhea also been reported rarely.”

    Cod Liver Oil · Natural Medicines adverse-effect record, reported in diarrhea.

    3 sources cited
    1. 3398. 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
    2. 94757. Gruenwald J, Graubaum HJ, Harde A. Effect of cod liver oil on symptoms of rheumatoid arthritis. Adv Ther 2002;19(2):101-7. PubMed
    3. 101990. 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

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Dizziness / Headache reported in 5.1% of FDA reports for Hydroxyurea Additional detail

    Cod Liver Oil

    “Orally, headache and dizziness have been reported in a single patient each after a single dose of cod liver oil.”

    Cod Liver Oil · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 101990. 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

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Nausea reported in 6.2% of FDA reports for Hydroxyurea Additional detail

    Cod Liver Oil

    Recorded for Cod Liver Oil in the same Natural Medicines adverse-effect record shown under A higher chance of infection above.

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • A skin rash Additional detail

    Cod Liver Oil

    “Topically, cod liver oil may cause allergic contact dermatitis. There is a case report of allergic contact dermatitis in an 80-year-old woman being treated for leg ulcers with various topical products including 40% cod liver oil ointment (Dermovitamina, Pasquale SRL).”

    Cod Liver Oil · Natural Medicines adverse-effect record, reported in dermatitis.

    1 source cited
    1. 94762. 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

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea. Read the label on DailyMed ›

Reported for Cod Liver Oil but not commonly for Hydroxyurea: stomach upset, bleeding in the gut, bloating or gas and heartburn.

Effects for Hydroxyurea come from the ADVERSE REACTIONS section of its FDA label; effects for Cod Liver Oil come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 21,027 voluntary FDA FAERS reports for Hydroxyurea that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Cod Liver Oil in Pregnancy & Breastfeeding

Pregnancy Possibly 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 RDAs are 770 mcg (2567 units of retinol) daily for pregnant women over 18 years of age, and 750 mcg (2500 units of retinol) daily for pregnant teenagers 14 years to 18 years of age. For vitamin D, the RDA is 15 mcg (600 units) daily for pregnant women of all ages. In clinical research, cod liver oil (Peter Möller, Oslo, Norway) 10 mL orally daily (providing vitamin A 1170 mcg and vitamin D 10 mcg daily) has been used safely from week 17 of pregnancy until delivery, and continuing for 3 months during lactation.

Pregnancy Possibly Unsafe

When used orally in excessive doses. Avoid doses of cod liver oil which contain more than the Tolerable Upper Intake levels (ULs) of vitamins A and D. For vitamin A, the ULs are 3000 mcg (10,000 units of retinol) daily for pregnant women over 18 years of age, and 2800 mcg (9333 units of retinol) daily for pregnant teenagers aged 14 years to 18 years. For vitamin D, the UL is 100 mcg (4000 units) daily for pregnant women of all ages.

Lactation Possibly 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 RDAs are 1300 mcg (4333 units of retinol) daily for lactating women over 18 years of age, and 1200 mcg (4000 units of retinol) daily for pregnant teenagers aged 14 years to 18 years. For vitamin D, the RDA is 15 mcg (600 units) daily for lactating women of all ages. An Icelandic cod liver oil, 10 mL daily, has been used safely for 4 months during lactation.

Lactation Possibly Unsafe

When used orally in excessive doses. Avoid doses of cod liver oil which contain more than the Tolerable Upper Intake levels (ULs) of vitamins A and D. For vitamin A, the ULs are 3000 mcg (10,000 units of retinol) daily for lactating women over 18 years of age, and 2800 mcg (9333 units of retinol) daily for lactating teenagers aged 14 years to 18 years. For vitamin D, the UL is 100 mcg (4000 units) daily for lactating women of all ages.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Cod Liver Oil or Hydroxyurea

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Cod Liver Oil or Hydroxyurea, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Hydroxyurea

This page covers Cod Liver Oil only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydroxyurea page lists 18 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 10 minor.

From our pharmacist’s overview on the Hydroxyurea page

“People take hydroxyurea (Droxia, Hydrea, Siklos, Xromi) for serious reasons, most often sickle cell disease or certain blood cancers, and it only works if a steady dose reaches the bloodstream. That is exactly what nearly all 18 supplements listed here can undermine, so this page earns real vigilance rather than a skim.”

Reviewed by 2 · Jul 18, 2026

Open the Hydroxyurea interaction page

One more smart check

Taking Cod Liver Oil as Part of a Dietary Supplement Product? Check It for Interactions

We hold 17 real supplement products containing Cod Liver Oil, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cod Liver Oil. Even though Cod Liver Oil itself has no known interaction with Hydroxyurea, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Cod Liver Oil and Hydroxyurea Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Cod Liver Oil
Steady interest

#943 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Hydroxyurea
Top 5%

#40 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Cod Liver Oil reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Cod Liver Oil and Hydroxyurea records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Cod Liver Oil

What is Cod Liver Oil?

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

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.

Liver of the Atlantic cod fish · Liquid oil, softgel capsules, flavored emulsions

An interaction check asks whether these two react with each other — it does not ask whether Cod Liver Oil is a good idea for someone in your situation. Here is what our Cod Liver Oil record says about it on its own.

Cod Liver Oil: dosing

There is no single official dose of cod liver oil for everyone. The right amount depends on the product's concentration of omega-3s and its vitamin A and D content, which vary widely between brands.The best approach is to follow the directions on the product label and not take more than recommended.

From our Cod Liver Oil monograph — the full record covers uses, side effects and every documented interaction.

Read the full Cod Liver Oil monograph & all interactions
Medication

About Hydroxyurea

What Is Hydroxyurea Used For?

Brand names: Droxia, Hydrea, Siklos, Xromi

Hydroxyurea is used for several serious conditions. Droxia, Siklos, and Xromi are each indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is approved for adults and children 2 years and older; Xromi is approved for children 6 months and older; Droxia is approved for adults.

Hydrea capsules and Hydroxyurea capsules are indicated for resistant chronic myeloid leukemia and for locally advanced squamous cell carcinomas of the head and neck (excluding the lip) when used together with chemoradiation.

Most-Reported Side Effects for Hydroxyurea

From FAERS, the FDA’s public side-effect reporting system (21,027 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 1,548 reports
Sickle cell anaemia with crisis 1,486 reports
Diarrhea 1,408 reports
Nausea 1,306 reports
Headache 1,068 reports
See full Hydroxyurea drug information
Keep checking

Other Drugs & Cod Liver Oil

Browse every other medication we’ve checked against Cod Liver Oil — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
375Moderate
0Minor
2,454No known interaction
375 Moderate 2,454 No interaction
Moderate

375 interactions

Showing 60 of 375 moderate interactions — see all 375 on the Cod Liver Oil page.

No interaction 2,454 drugs checked — show the list

We also checked Cod Liver Oil against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,454 medications checked with no known interaction — see the full Cod Liver Oil list.

See the full Cod Liver Oil interactions page
See every supplement checked against Hydroxyurea, ranked by severity
Evidence & sources

Cod Liver Oil References

The 20 references that drive our Cod Liver Oil monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  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

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Cod Liver Oil and Hydroxyurea Together: Common Questions

Is it safe to take Cod Liver Oil with Hydroxyurea?
We do not list a known interaction between Cod Liver Oil and Hydroxyurea. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Cod Liver Oil and Hydroxyurea have any of the same side effects?
Yes — our sources link each of them separately to 7 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Cod Liver Oil and Hydroxyurea combination checked?
Interactions in our licensed database are recorded against drug classes. Hydroxyurea is filed under 2 classifications, and Cod Liver Oil has documented interactions with 3 drug classes — none of Hydroxyurea's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Cod Liver Oil interact with any other medications?
Yes. Cod Liver Oil has 375 documented drug interactions in our database — Hydroxyurea is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Hydroxyurea interact with any supplements?
Yes. Hydroxyurea has documented interactions with 18 supplements in our database — Cod Liver Oil is not one of them. The Hydroxyurea interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Cod Liver Oil monograph Uses, safety profile, and every drug interaction in one place Hydroxyurea drug information The full plain-English guide to this medication Hydroxyurea supplement interactions Every supplement checked against Hydroxyurea, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 20 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Hydroxyurea and Cod Liver Oil?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.