Drug & supplement interaction

Castoreum + Metoprolol

Metoprolol brand names: Lopressor, Toprol XL.

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

We found no known interaction between Castoreum and Metoprolol 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 Metoprolol states a food rule worth keeping to.

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Interaction report

Castoreum and Metoprolol

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 Metoprolol 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 Metoprolol, 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 Metoprolol and Castoreum? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Metoprolol’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 Metoprolol’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. 10 of them are worth acting on rather than waiting out — marked below.

  • Memory problems Worth acting on
  • A slow heartbeat Worth acting on
  • A heart attack Worth acting on
  • Hallucinations Worth acting on
  • Heart failure Worth acting on
  • Fainting Worth acting on
  • Wheezing Worth acting on
  • Confusion Worth acting on
  • Chest pain Worth acting on
  • Low mood Worth acting on

Showing the 10 most notable of 47 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 Metoprolol. Read the label on DailyMed › 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.

How to take them

Some Metoprolol Products Have a Food Rule — Castoreum Should Not Break It

At least one FDA label for a product containing Metoprolol says to take it with food. If you take Castoreum on an empty stomach out of habit, keep them separate — and take Metoprolol with a meal where the label says to.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Metoprolol 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.

Administer once daily with food or after a meal.

From the Dosage and Administration section of the FDA label we read for Metoprolol — 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.

From our Q&A

Questions About Castoreum or Metoprolol

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Castoreum or Metoprolol, 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 Metoprolol

This page covers Castoreum only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metoprolol page lists 183 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), Indian Snakeroot (major) and Tyramine (major).

By severity: 5 major · 152 moderate · 26 minor.

From our pharmacist’s overview on the Metoprolol page

“With metoprolol (Lopressor, Toprol XL), a beta-blocker for high blood pressure and heart problems, these interactions deserve genuine care, starting with the five rated major. Most entries pull blood pressure one way or the other: many supplements add to metoprolol's lowering effect and can drop pressure too far, while a few, tyramine…”

Reviewed by 2 · Jul 18, 2026

Open the Metoprolol interaction page

How much people look this up

Where Castoreum and Metoprolol 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

#1,248 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Metoprolol
Top 10

#7 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 13, 2026. The Castoreum and Metoprolol 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 Metoprolol

What Is Metoprolol Used For?

Brand names: Lopressor, Toprol XL

Metoprolol is used to treat several heart and blood pressure conditions. Metoprolol succinate extended-release tablets (including Toprol-XL) are approved for high blood pressure, angina pectoris (chest pain from the heart), and heart failure. Metoprolol tartrate tablets (including Lopressor) are approved for high blood pressure, angina, and — when used alongside intravenous metoprolol — to reduce the risk of cardiovascular death after a definite or suspected heart attack.

Metoprolol tartrate injection (intravenous form) is used in hemodynamically stable patients with a definite or suspected acute heart attack to reduce cardiovascular death, and is followed by oral metoprolol therapy. Lowering blood pressure with metoprolol reduces the risk of strokes and heart attacks.

Most-Reported Side Effects for Metoprolol

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 23,416 reports
Dyspnea 20,183 reports
Diarrhea 19,912 reports
Nausea 19,659 reports
Dizziness 16,726 reports
See full Metoprolol 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 Metoprolol, 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 Metoprolol Together: Common Questions

Is it safe to take Castoreum with Metoprolol?
We do not list a known interaction between Castoreum and Metoprolol. 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.
Should I take Castoreum and Metoprolol at the same time of day?
At least one FDA label for a product containing Metoprolol says to take it with food. If you take Castoreum on an empty stomach out of habit, keep them separate and take Metoprolol with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Metoprolol products can differ — so check the directions on your own box. This is about absorption, not an interaction.
Does Metoprolol interact with any supplements?
Yes. Metoprolol has documented interactions with 183 supplements in our database — Castoreum is not one of them. The Metoprolol 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 Metoprolol drug information The full plain-English guide to this medication Metoprolol supplement interactions Every supplement checked against Metoprolol, 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 Metoprolol 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.