Drug & supplement interaction

Cod Liver Oil + Methyclothiazide

Methyclothiazide brand names: Enduron, Aquatensen.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Cod Liver Oil has a moderate interaction with Methyclothiazide. Theoretically, taking cod liver oil with antihypertensive drugs might increase the risk of hypotension.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Cod Liver Oil and Methyclothiazide

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Methyclothiazide

Methyclothiazide falls under ANTIHYPERTENSIVE DRUGS — the group Cod Liver Oil interacts with.

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.
Severity Moderate Likelihood Probable Evidence B

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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist: methyclothiazide is a water pill that lowers your blood pressure by helping your body shed extra salt and fluid. Cod liver oil, thanks to its omega-3 fats, can gently nudge blood pressure down too. So when you pair them, those effects can stack on top of each other and push your pressure a little lower than you'd planned.

If that happens, you might feel dizzy or lightheaded, especially when you stand up quickly, and you may notice more tiredness. This is mostly a theoretical, additive concern rather than a dangerous clash, and culinary or modest doses are unlikely to cause trouble. Still, it's worth a quick chat with your pharmacist or doctor, who may simply want to keep an eye on your blood pressure readings.

Contact Dr. Brian directly if you have additional questions on this interaction
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. 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

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Cod Liver Oil Also Interacts With Other Medications

Cod Liver Oil has 374 moderate known drug interactions in our database — the Methyclothiazide one above is one of them. If you take anything else, check it against the full list below.

Moderate 374 No known interaction 2,456 (incl. Methyclothiazide)
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.

From our Q&A

Questions About Cod Liver Oil or Methyclothiazide

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 Methyclothiazide, 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 Methyclothiazide

This page covers Cod Liver Oil only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methyclothiazide page lists 227 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Asarabacca (major) and Dolomite (major).

By severity: 10 major · 192 moderate · 25 minor.

Open the Methyclothiazide 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. Your product may carry other ingredients that interact with Methyclothiazide too, on top of Cod Liver Oil — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Cod Liver Oil and Methyclothiazide 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
Top half

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

29 days ago today
Medication Methyclothiazide
Top half

#1,075 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.

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.

Read the full Cod Liver Oil monograph & all interactions
Medication

About Methyclothiazide

What Is Methyclothiazide Used For?

Brand names: Enduron, Aquatensen

  • Methyclothiazide is used to treat high blood pressure. Methyclothiazide is also used to treat edema (fluid retention; excess fluid held in body tissues) caused by various medical problems, including heart, kidney, and liver disease and to treat edema caused by using certain medications including estrogen and corticosteroids. Methyclothiazide is in a class of medications called diuretics ('water pills'). It works by causing the kidneys to get rid of unneeded water and salt from the body into the urine.

  • High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.

See full Methyclothiazide 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
374Moderate
0Minor
2,455No known interaction
374 Moderate 2,455 No interaction
Moderate

374 interactions

Showing 60 of 374 moderate interactions — see all 374 on the Cod Liver Oil page.

No interaction 2,455 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 2,455 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 Methyclothiazide, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

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

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

Taking Cod Liver Oil and Methyclothiazide Together: Common Questions

Can you take Cod Liver Oil with Methyclothiazide?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Cod Liver Oil and Methyclothiazide interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Methyclothiazide 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.