Shark Liver Oil + Methylnaltrexone
Methylnaltrexone brand name: Relistor.
We found no known interaction between Shark Liver Oil and Methylnaltrexone 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 label for Methylnaltrexone states a food rule worth keeping to, and 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.
Shark Liver Oil and Methylnaltrexone
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 Methylnaltrexone and Shark 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.
Worth understanding: our licensed dataset holds no drug-interaction record for Shark Liver Oil at all — not against Methylnaltrexone, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.
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.
Shark Liver Oil safety at a glance
Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
Some Methylnaltrexone Products Have a Food Rule — Shark Liver Oil Should Not Break It
At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach. Most supplements — Shark Liver Oil included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Methylnaltrexone on its own and move Shark Liver Oil to a meal later in the day.
This may not be true of your version. Food instructions belong to the product, not the ingredient: two Methylnaltrexone products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.
o In patients with chronic non-cancer pain and OIC, take RELISTOR tablets with water on an empty stomach at least 30 minutes before the first meal of the day.
From the Dosage and Administration section of the FDA label we read for Methylnaltrexone — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›
A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.
What Methylnaltrexone Is Prescribed For, and What Shark Liver Oil Has Been Studied For
These two come up together because they touch the same health topic — not because they do the same job. Methylnaltrexone is a prescription medicine with approved uses on its FDA label. Shark Liver Oil is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.
Methylnaltrexone is prescribed for: Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases. Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.
Shark Liver Oil has been studied for:
-
Cancer studied, not established Shark Liver Oil has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows
Shark Liver Oil for cancer
Although there has been interest in using oral shark liver oil for cancer, there is insufficient reliable information about the clinical effects of shark liver oil for this purpose.
Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Methylnaltrexone on your own; if you are taking Shark Liver Oil for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.
See Every Supplement That Interacts With Methylnaltrexone
This page covers Shark Liver Oil only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methylnaltrexone page lists 3 supplements it has a documented interaction with, worst first, each one explained.
The most serious there right now: Fever Bark (moderate), Iboga (moderate) and Yohimbe (moderate).
By severity: 3 moderate.
From our pharmacist’s overview on the Methylnaltrexone page
“If you take methylnaltrexone (Relistor) for opioid-induced constipation, the supplement list to know is short: three ingredients, all rated moderate, none major. Yohimbe, fever bark, and iboga are all cleared by the same liver enzyme, CYP2D6, and methylnaltrexone can slow that enzyme, letting their active compounds build up in your blood.”
Reviewed by 2 · Jul 18, 2026
Taking Shark Liver Oil as Part of a Dietary Supplement Product? Check It for Interactions
We hold 20 real supplement products containing Shark Liver Oil, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Shark Liver Oil. Even though Shark Liver Oil itself has no known interaction with Methylnaltrexone, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:
Where Shark Liver Oil and Methylnaltrexone 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.
#1,326 of 1,452 supplements looked up here in the last 7 days
#2,634 of 2,830 medications looked up here in the last 7 days
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 Shark Liver Oil reference on this page ↓
- Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Shark Liver Oil and Methylnaltrexone records this page draws on were last updated July 10, 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.
About Shark Liver Oil
What is Shark Liver Oil?
- Immune support
- Skin conditions and wound healing
- Cancer support (unproven)
- Hemorrhoid relief (topical)
- Cold and flu prevention
- General wellness tonic
Shark liver oil is taken from the livers of deep-sea sharks and is rich in compounds called alkylglycerols and squalene. People use it for immune support, skin healing, and other conditions, but strong human evidence is largely lacking. Talk to your pharmacist or doctor before using it, especially since sustainability and contamination are concerns.
Liver oil from deep-sea sharks · Capsules, softgels, liquid oil, topical creams and ointments
An interaction check asks whether these two react with each other — it does not ask whether Shark Liver Oil is a good idea for someone in your situation. Here is what our Shark Liver Oil record says about it on its own.
Shark Liver Oil: dosing
There is no official or well-established dose for shark liver oil. Products differ in how much alkylglycerol or squalene they contain, so amounts on labels vary.The safest approach is to follow the directions on the product label and not take more than recommended.
From our Shark Liver Oil monograph — the full record covers uses, side effects and every documented interaction.
About Methylnaltrexone
What Is Methylnaltrexone Used For?
Brand name: Relistor
Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases.
Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.
Other Drugs & Shark Liver Oil
Browse every other medication we’ve checked against Shark Liver Oil — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
No interaction 2,829 drugs checked — show the list
We also checked Shark Liver Oil against these medications and found no known interaction in our sources. Open any page to confirm.
- Apixaban ›
- Levothyroxine ›
- Amlodipine ›
- Warfarin ›
- Methylphenidate ›
- Sertraline ›
- Testosterone ›
- Losartan Potassium ›
- Ivermectin ›
- Metoprolol ›
- Aspirin ›
- Rivaroxaban ›
- Acetaminophen ›
- Rosuvastatin ›
- Abemaciclib ›
- Escitalopram ›
- Clopidogrel ›
- Tadalafil ›
- Atorvastatin ›
- Docusate ›
- Tirzepatide ›
- Ibuprofen ›
- Hydroxyurea ›
- Valacyclovir ›
- Methamphetamine ›
- Warfarin Sodium ›
- Semaglutide ›
- Sumatriptan ›
- Prednisone ›
- Propranolol ›
- Lisdexamfetamine ›
- Metformin ›
- Amoxicillin ›
- Lisinopril ›
- Amitriptyline ›
- Bupropion ›
- Methotrexate ›
- Bendamustine ›
- Amphetamine ›
- Acyclovir ›
- Doxycycline ›
- Isotretinoin ›
- Fluoxetine ›
- Pregabalin ›
- Lamotrigine ›
- Amlodipine Besylate ›
- Azithromycin ›
- Gabapentin ›
- Acetaminophen, Codeine ›
- Dextroamphetamine ›
- Clonazepam ›
- Methylene Blue ›
- Quetiapine ›
- Omeprazole ›
- Letrozole ›
- Naproxen ›
- Duloxetine ›
- Buspirone ›
- Citalopram ›
- Ciprofloxacin ›
Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Shark Liver Oil list.
Shark Liver Oil References
The 6 references that drive our Shark 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.
- Lee JY, Lee KS, Kim TS, et al. Squalene-induced extrinsic lipoid pneumonia: serial radiologic findings in nine patients. J Comput Assist Tomogr 1999;23:730-5. PubMed
- Lee JS, Im JG, Song KS, et al. Exogenous lipoid pneumonia: high-resolution CT findings. Eur Radiol 1999;9:287-91. PubMed
- Asnis DS, Saltzman HP, Melchert A. Shark oil pneumonia. An overlooked entity. Chest 1993;103:976-7.
- Deniau AL, Mosset P, Pédrono F, Mitre R, Le Bot D, Legrand AB. Multiple beneficial health effects of natural alkylglycerols from shark liver oil. Mar Drugs. 2010 Jul 19;8(7):2175-84. PubMed
- Kilincalp S, Deveci M, Basar O, Ekiz F, Coban S, Yuksel O. Shark liver oil: hidden dangers. Ann Hepatol. 2012 Sep-Oct;11(5):728-30. DOI
- Hamadate N, Matsumoto Y, Seto K, Yamamoto T, Yamaguchi H, Nakagawa T, Yamamoto E, Fukagawa M, Yazawa K. Vascular effects and safety of supplementation with shark liver oil in middle-aged and elderly males. Exp Ther Med. 2015 Aug;10(2):641-646. Epub 2015 J 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.
Taking Shark Liver Oil and Methylnaltrexone Together: Common Questions
Is it safe to take Shark Liver Oil with Methylnaltrexone?
Do Shark Liver Oil and Methylnaltrexone have any of the same side effects?
Should I take Shark Liver Oil and Methylnaltrexone at the same time of day?
Are Shark Liver Oil and Methylnaltrexone used for the same thing?
Does Methylnaltrexone interact with any supplements?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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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.