Drug & supplement interaction

Calamus + Carvedilol

Carvedilol brand names: Coreg, Coreg CR.

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

Carvedilol falls into 2 drug categories that Calamus can interact with; the most serious is rated moderate. Theoretically, taking calamus with other antihypertensive medications might increase the risk of hypotension.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Calamus and Carvedilol

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Calamus interacts with whole categories of medication. Carvedilol falls into 2 of those categories, so it can interact with Calamus in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIHYPERTENSIVE DRUGS

1 of 2

Why this applies to Carvedilol

Carvedilol falls under ANTIHYPERTENSIVE DRUGS — the group Calamus interacts with.

Theoretically, taking calamus with other antihypertensive medications might increase the risk of hypotension.
Animal research shows that calamus decreases the rate and strength of the heartbeat, which might lower blood pressure. use with caution.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

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

Here's the thing about pairing calamus with carvedilol: both can push your blood pressure and heart rate in the same downward direction. Carvedilol already relaxes your blood vessels and slows your heartbeat to lower blood pressure. In animal studies, calamus seems to do something similar, weakening the rate and force of the heartbeat. Stacking the two together could, in theory, lower your numbers more than you want.

What might that feel like? Dizziness, lightheadedness when you stand up, unusual tiredness, or a slow pulse. I'll be honest, this concern comes only from lab and animal research, not solid human studies, so it's more of a caution than a proven problem. Calamus also has real safety issues of its own. Please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Panchal, G. M., Venkatakrishna-Bhatt, H., Doctor, R. B., and Vajpayee, S. Pharmacology of Acorus calamus L. Indian J Exp.Biol 1989;27(6):561-567.
Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 2

Carvedilol also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, taking calamus with drugs metabolized by CYP2D6 might increase drug levels and potentially increase the risk of adverse effects.
In vitro research shows that calamus extract inhibits CYP2D6 enzyme.
Severity Moderate Likelihood Possible Evidence D

Interaction 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.

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

Here's the gist: your body uses an enzyme called CYP2D6 to help clear carvedilol (Coreg). Lab studies suggest calamus may slow that enzyme down. If that happened in real life, carvedilol could build up a bit more than expected, which might make its blood-pressure and heart-rate lowering effects stronger. In practice that could mean feeling dizzy, lightheaded, unusually tired, or noticing your pulse running slow.

I want to be honest about the evidence though, this is only a theoretical concern based on test-tube research, not studies in people, so we really don't know how much it matters. On top of that, calamus carries its own safety worries and the FDA banned it from foods. I'd skip it, but please check with your pharmacist or doctor before mixing the two or making any changes.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pandit S, Mukherjee PK, Ponnusankar S, Venkatesh M, Srikanth N. Metabolism mediated interaction of a-asarone and Acorus calamus with CYP3A4 and CYP2D6. Fitoterapia 2011;82(3):369-74.

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

Calamus Also Interacts With Other Medications

Calamus has 1,097 moderate, 19 minor known drug interactions in our database — the Carvedilol one above is among them. If you take anything else, check it against the full list below.

Moderate 1,097 Minor 19 No known interaction 1,714 (incl. Carvedilol)
Taking anything else?

Check Another of Your Medications Against Calamus

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

From our Q&A

Questions About Calamus or Carvedilol

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

This page covers Calamus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carvedilol page lists 211 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), Grapefruit (major) and Indian Snakeroot (major).

By severity: 6 major · 171 moderate · 34 minor.

From our pharmacist’s overview on the Carvedilol page

“People take carvedilol (Coreg) for heart failure and high blood pressure, conditions where a sudden swing in pressure or heart rate matters, and its supplement list runs to 211 ingredients, so this one calls for genuine care. More than half of those entries lower blood pressure on their own, fish oil and celery seed among them, and can…”

Reviewed by 2 · Jul 18, 2026

Open the Carvedilol interaction page

One more smart check

Taking Calamus as Part of a Dietary Supplement Product? Check It for Interactions

We hold 71 real supplement products containing Calamus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Calamus. Your product may carry other ingredients that interact with Carvedilol too, on top of Calamus — 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 Calamus and Carvedilol 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 Calamus
Steady interest

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

29 days ago today
Medication Carvedilol
Top 25%

#303 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 Calamus

What is Calamus?

Calamus
  • Digestive upset and gas
  • Loss of appetite
  • Memory and focus (traditional)
  • Coughs and colds
  • Calming or sedative effect (traditional)

Calamus is a swamp plant with a long history in Ayurvedic and traditional Chinese medicine, mostly for digestive and nervous-system complaints. However, it contains beta-asarone, a compound linked to cancer and other toxic effects in animal studies, which is why the U.S. FDA banned it from foods. Because of these safety concerns and a lack of solid human evidence, it is generally best avoided.

Read the full Calamus monograph & all interactions
Medication

About Carvedilol

What Is Carvedilol Used For?

Brand names: Coreg, Coreg CR

Carvedilol is used to treat three main conditions: mild-to-severe chronic heart failure, high blood pressure (hypertension), and reduced heart pumping function (left ventricular dysfunction) in people who have survived a heart attack. For heart failure, it is usually prescribed alongside other medications such as diuretics, ACE inhibitors, and digitalis to help people live longer and reduce the chance of hospital stays.

For people who have had a heart attack and whose heart is not pumping as well as it should, carvedilol is used to lower the risk of dying from heart-related causes. For high blood pressure, it can be used on its own or combined with other blood pressure medicines.

See full Carvedilol drug information
Keep checking

Other Drugs & Calamus

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

0Major
1,097Moderate
19Minor
1,713No known interaction
1,097 Moderate 19 Minor 1,713 No interaction
Moderate

1,097 interactions

Showing 60 of 1,097 moderate interactions — see all 1,097 on the Calamus page.

Minor

19 interactions

No interaction 1,713 drugs checked — show the list

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

Showing the 60 most looked-up of 1,713 medications checked with no known interaction — see the full Calamus list.

See the full Calamus interactions page
See every supplement checked against Carvedilol, 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
Calamus monograph › Uses, safety, and every drug interaction in one place Carvedilol supplement interactions › Every supplement checked against Carvedilol, ranked by severity Carvedilol 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 Calamus and Carvedilol Together: Common Questions

Can you take Calamus with Carvedilol?
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.
Why are there 2 interactions listed for Calamus and Carvedilol?
Carvedilol belongs to more than one drug category, and Calamus interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Calamus and Carvedilol 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 Carvedilol and Calamus?

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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.