Drug & supplement interaction

Castoreum + Eribulin Mesylate

Eribulin Mesylate brand name: Halaven.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Castoreum and Eribulin Mesylate 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.

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Interaction report

Castoreum and Eribulin Mesylate

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 Eribulin Mesylate and Castoreum 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 Castoreum at all — not against Eribulin Mesylate, 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.

Castoreum safety at a glance

Castoreum overall Not established Modern safety data for medicinal use is essentially lacking, so caution is warranted.
Pregnancy Avoid There is no safety data; avoid medicinal use during pregnancy.
Breastfeeding Avoid There is no safety data; avoid medicinal use while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Eribulin Mesylate and Castoreum? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Eribulin Mesylate’s Own FDA Label Lists

This is not an interaction — none of it involves Castoreum. These are the most notable effects listed in the ADVERSE REACTIONS section of Eribulin Mesylate’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 4 of them are worth acting on rather than waiting out — marked below.

  • A low white blood cell count Worth acting on mentioned in 28.9% of FDA reports for Eribulin Mesylate
  • Low potassium Worth acting on
  • An irregular heartbeat Worth acting on
  • Anemia Worth acting on
  • Fever mentioned in 14.7% of FDA reports for Eribulin Mesylate
  • Numbness or tingling mentioned in 5.8% of FDA reports for Eribulin Mesylate
  • Hair loss
  • Constipation
  • Stomach pain
  • Tiredness

Showing the 10 most notable of 12 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Eribulin Mesylate. Read the label on DailyMed › Where a percentage is shown, it is the share of 3,719 voluntary FDA FAERS reports for Eribulin Mesylate that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Castoreum’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Castoreum side to compare — that is a limit of the record, not a statement that Castoreum has no side effects.

Everything else you take

See Every Supplement That Interacts With Eribulin Mesylate

This page covers Castoreum only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Eribulin Mesylate page lists 13 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: American Hellebore (major), Arsenic (major), Cesium (major), Ephedra (major) and Grapefruit (major).

By severity: 6 major · 7 moderate.

From our pharmacist’s overview on the Eribulin Mesylate page

“Eribulin mesylate (Halaven) is an infused chemotherapy, used most often for advanced breast cancer, and one of its known effects is stretching the heart's QT interval, the recovery pause between beats on an ECG. All 13 supplements on this page can do the same thing, so pairing any of them with eribulin stacks that strain and raises the…”

Reviewed by 2 · Jul 18, 2026

Open the Eribulin Mesylate interaction page

How much people look this up

Where Castoreum and Eribulin Mesylate 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 Castoreum
Steady interest

#1,089 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Eribulin Mesylate
Steady interest

#2,333 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. Castoreum is not yet covered by that licensed database, so its write-up cites publicly available medical sources directly (see the references below).
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Castoreum reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Castoreum and Eribulin Mesylate records this page draws on were last updated June 22, 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 Castoreum

What is Castoreum?

  • Traditional remedy for menstrual or 'hysteria' complaints
  • Folk use for headache and pain
  • Flavoring agent (vanilla-like notes)
  • Fragrance and perfume ingredient
  • Historical use as a sedative or antispasmodic

Castoreum is a brownish, strong-smelling substance taken from the castor sacs of beavers, not a plant. It has a long history in perfumes, flavorings, and folk medicine, but there is no reliable modern evidence that it treats any health condition, so it should not be relied on as a medicine.

Castor sac secretion (castoreum) from beavers, sometimes combined with castor gland and surrounding tissue · Tincture (in traditional and homeopathic medicine), perfume and fragrance ingredient, food flavoring extract

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

Castoreum: dosing

There is no established or standardized medicinal dose for castoreum. It is not a recognized medicine, and reliable dosing guidelines do not exist.If you encounter a product that contains castoreum (for example, a traditional tincture or homeopathic preparation), follow the directions on the label and do not exceed them.

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

Read the full Castoreum monograph & all interactions
Medication

About Eribulin Injection

What Is Eribulin Injection Used For?

Brand name: Halaven

Eribulin mesylate injection (brand name Halaven) is used to treat metastatic breast cancer in patients who have already received at least two prior chemotherapy regimens for metastatic disease, including an anthracycline and a taxane. It is also approved for unresectable or metastatic liposarcoma in patients who have received a prior anthracycline-containing regimen.

Both uses are for advanced cancers that have already been treated with other therapies. This is not a first-line treatment — it is used when the cancer has progressed despite earlier chemotherapy.

Most-Reported Side Effects for Eribulin Mesylate

From FAERS, the FDA’s public side-effect reporting system (3,719 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Neutropenia 537 reports
Malignant neoplasm progression 382 reports
Febrile neutropenia 331 reports
Myelosuppression 310 reports
Fever 215 reports
See full Eribulin Injection drug information
Keep checking

Other Drugs & Castoreum

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Castoreum list.

See the full Castoreum interactions page
See every supplement checked against Eribulin Mesylate, ranked by severity
Evidence & sources

Castoreum References

The 3 sources that drive our Castoreum monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing. Castoreum is not covered by the licensed Natural Medicines interaction database, so its page cites these public sources directly.

  1. Castoreum (chemical information) — PubChem (NIH National Library of Medicine) Source
  2. Dietary Supplements: What You Need to Know — NIH Office of Dietary Supplements Source
  3. Herbal Medicine — MedlinePlus (NIH National Library of Medicine) Source

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 Castoreum and Eribulin Mesylate Together: Common Questions

Is it safe to take Castoreum with Eribulin Mesylate?
We do not list a known interaction between Castoreum and Eribulin Mesylate. 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.
Does Eribulin Mesylate interact with any supplements?
Yes. Eribulin Mesylate has documented interactions with 13 supplements in our database — Castoreum is not one of them. The Eribulin Mesylate 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

Castoreum monograph Uses, safety profile, and every drug interaction in one place Eribulin Injection drug information The full plain-English guide to this medication Eribulin Mesylate supplement interactions Every supplement checked against Eribulin Mesylate, 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 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Eribulin Mesylate and Castoreum?

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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.