Drug & supplement interaction

Calamus + Ergotamine, Belladonna, Phenobarbital

Ergotamine, Belladonna, Phenobarbital brand names: Bellaspas, Bellamine, Eperbel-S.

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

Ergotamine, Belladonna, Phenobarbital falls into 3 drug categories that Calamus can interact with; the most serious is rated moderate. Theoretically, concurrent use of CNS depressants and calamus might have an additive effect and increase the risk of sedative effects.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Calamus and Ergotamine, Belladonna, Phenobarbital

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Calamus interacts with whole categories of medication. Ergotamine, Belladonna, Phenobarbital falls into 3 of those categories, so it can interact with Calamus in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CNS DEPRESSANTS

1 of 3

Why this applies to Ergotamine, Belladonna, Phenobarbital

Ergotamine, Belladonna, Phenobarbital falls under CNS DEPRESSANTS — the group Calamus interacts with.

Theoretically, concurrent use of CNS depressants and calamus might have an additive effect and increase the risk of sedative effects.
Animal research shows that calamus is a CNS depressant and increases gamma-aminobutyric acid levels.
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

This combination product contains phenobarbital, a barbiturate that calms the nervous system. Calamus, in animal studies, appears to act as a mild nervous-system depressant by raising levels of GABA, a calming brain chemical. When you stack two things that slow the brain down, their drowsy effects can add up.

So in theory, taking calamus alongside this medicine could leave you feeling extra sleepy, foggy, dizzy, or unsteady on your feet. Keep in mind this is a theoretical concern based on animal research, not proven in people. Even so, calamus has its own safety worries (it's banned from foods in the U.S.), so it's best avoided. Please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Koo, B. S., Park, K. S., Ha, J. H., Park, J. H., Lim, J. C., and Lee, D. U. Inhibitory effects of the fragrance inhalation of essential oil from Acorus gramineus on central nervous system. Biol Pharm.Bull. 2003;26(7):978-982. PubMed
  3. 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 3A4 (CYP3A4) SUBSTRATES

2 of 3

Ergotamine, Belladonna, Phenobarbital also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, taking calamus with drugs metabolized by CYP3A4 might increase drug levels and potentially increase the risk of adverse effects.
In vitro research shows that calamus extract inhibits CYP3A4 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

This combination product mixes ergotamine, belladonna, and phenobarbital, and it's often used for tension or migraine-type headaches. The piece that matters here is ergotamine, which your liver clears using an enzyme called CYP3A4. In test-tube studies, calamus appears to slow that same enzyme down. If that happens in real life, ergotamine could build up more than expected.

Why care? Too much ergotamine can cause problems like nausea, tingling or coldness in your fingers and toes, leg cramps, and in rare cases poor circulation. Keep in mind this warning comes only from lab research, not human studies, so it's theoretical. Still, given calamus has its own safety worries, please check with your pharmacist or doctor before pairing them.

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.
Moderate

ANTICHOLINERGIC DRUGS

3 of 3

Ergotamine, Belladonna, Phenobarbital also falls under ANTICHOLINERGIC DRUGS.

Theoretically, concurrent use of anticholinergic drugs and calamus might decrease the effectiveness of the anticholinergic drug.
In vitro evidence shows that calamus can inhibit acetylcholinesterase (AChE).
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

This combination product contains belladonna, which works as an anticholinergic, meaning it blocks acetylcholine to help calm cramping in the gut and ease related symptoms. Here's where calamus comes in: lab studies suggest it can block an enzyme (acetylcholinesterase) that normally breaks down acetylcholine. More acetylcholine hanging around could push back against what belladonna is trying to do, so in theory calamus might make the belladonna part work less well.

I want to be honest that this is theoretical and based only on test-tube and animal data, not real people, so I wouldn't lose sleep over it. Honestly, the bigger concern is calamus itself, since it contains beta-asarone and is banned from U.S. foods for safety reasons. I'd skip the calamus and chat with your pharmacist or doctor before using it alongside this medication.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Oh, M. H., Houghton, P. J., Whang, W. K., and Cho, J. H. Screening of Korean herbal medicines used to improve cognitive function for anti-cholinesterase activity. Phytomedicine 2004;11(6):544-548. 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

Calamus Also Interacts With Other Medications

Calamus has 1,099 moderate, 19 minor known drug interactions in our database — the Ergotamine, Belladonna, Phenobarbital one above is among them. If you take anything else, check it against the full list below.

Moderate 1,099 Minor 19 No known interaction 1,712 (incl. Ergotamine, Belladonna, Phenobarbital)
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.

Everything else you take

See Every Supplement That Interacts With Ergotamine, Belladonna, Phenobarbital

This page covers Calamus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ergotamine, Belladonna, Phenobarbital page lists 250 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Grapefruit (major).

By severity: 11 major · 200 moderate · 39 minor.

From our pharmacist’s overview on the Ergotamine, Belladonna, Phenobarbital page

“Sedation stacking is the risk I would put first with ergotamine, belladonna, and phenobarbital (Bellamine, Bellaspas). Phenobarbital is a barbiturate, sedating on its own, and 78 of the ingredients on this page deepen that drowsiness, alcohol most seriously of all.”

Reviewed by 2 · Jul 18, 2026

Open the Ergotamine, Belladonna, Phenobarbital 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 Ergotamine, Belladonna, Phenobarbital 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 Ergotamine, Belladonna, Phenobarbital 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
Top half

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

29 days ago today
Medication Ergotamine, Belladonna, Phenobarbital
Top 10%

#219 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
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
1,099Moderate
19Minor
1,711No known interaction
1,099 Moderate 19 Minor 1,711 No interaction
Moderate

1,099 interactions

Showing 60 of 1,099 moderate interactions — see all 1,099 on the Calamus page.

Minor

19 interactions

No interaction 1,711 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 1,711 medications checked with no known interaction — see the full Calamus list.

See the full Calamus interactions page
See every supplement checked against Ergotamine, Belladonna, Phenobarbital, 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 Ergotamine, Belladonna, Phenobarbital supplement interactions › Every supplement checked against Ergotamine, Belladonna, Phenobarbital, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Calamus and Ergotamine, Belladonna, Phenobarbital Together: Common Questions

Can you take Calamus with Ergotamine, Belladonna, Phenobarbital?
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 3 interactions listed for Calamus and Ergotamine, Belladonna, Phenobarbital?
Ergotamine, Belladonna, Phenobarbital 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 Ergotamine, Belladonna, Phenobarbital 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 Ergotamine, Belladonna, Phenobarbital and Calamus?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.