Drug & supplement interaction

Calabar Bean + Methantheline Bromide

Methantheline Bromide brand name: Banthine.

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

Calabar Bean has a minor interaction with Methantheline Bromide. Theoretically, taking calabar bean might reduce the effects of anticholinergic drugs.

Read the full interaction report
SeverityMinor
LikelihoodUnlikely
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Calabar Bean and Methantheline Bromide

Here is the interaction we found between these two, with the evidence behind it.

Minor

ANTICHOLINERGIC DRUGS

Why this applies to Methantheline Bromide

Methantheline Bromide falls under ANTICHOLINERGIC DRUGS — the group Calabar Bean interacts with.

Theoretically, taking calabar bean might reduce the effects of anticholinergic drugs.
Physostigmine, a constituent of calabar bean, reverses the effects of belladonna and other drugs with anticholinergic activity.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Here's the simple version. Methantheline (Banthine) is an anticholinergic drug. It works by blocking acetylcholine, which is the chemical that revs up things like stomach cramping, gut activity, and certain secretions. Calabar bean contains physostigmine, which does the opposite. It makes acetylcholine build up, so in theory it could push back against what your methantheline is doing and weaken its calming effect on your stomach and bladder.

In plain terms, the two work against each other. That said, this is a theoretical concern based on how the chemicals behave, not something well documented. The bigger issue is that Calabar bean itself is genuinely poisonous and is not a safe supplement to take at all. Please run anything you're considering by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

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

Calabar Bean Also Interacts With Other Medications

Calabar Bean has 194 minor known drug interactions in our database — the Methantheline Bromide one above is one of them. If you take anything else, check it against the full list below.

Minor 194 No known interaction 2,636 (incl. Methantheline Bromide)
Taking anything else?

Check Another of Your Medications Against Calabar Bean

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

Everything else you take

See Every Supplement That Interacts With Methantheline Bromide

This page covers Calabar Bean only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methantheline Bromide page lists 46 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Henbane (major), Scopolia (major), Angel's Trumpet (moderate) and Bacopa (moderate).

By severity: 3 major · 32 moderate · 11 minor.

From our pharmacist’s overview on the Methantheline Bromide page

“Methantheline bromide (Banthine) is an anticholinergic, prescribed to calm cramping in an overactive gut or bladder, and this list deserves real caution before you add supplements. Three of the 46 entries rate major, and one of them, activated charcoal, shows up in everyday remedies for gas and stomach upset.”

Reviewed by 2 · Jul 18, 2026

Open the Methantheline Bromide interaction page

How much people look this up

Where Calabar Bean and Methantheline Bromide 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 Calabar Bean
Steady interest

#1,166 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Methantheline Bromide
Steady interest

#2,480 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 Calabar Bean

What is Calabar Bean?

Calabar Bean
  • Source of physostigmine (a prescription drug ingredient)
  • Historically used in 'trial by ordeal' rituals
  • Traditional pain relief and anti-inflammatory uses
  • Historically used for eye conditions (glaucoma)
  • Historically used as a poison

Calabar bean is a highly poisonous West African seed that contains physostigmine, a powerful cholinesterase inhibitor. It is not a safe dietary supplement, and eating the bean can cause serious poisoning or death. Only the purified, regulated drug physostigmine has a legitimate medical use, and that must be prescribed and monitored by a doctor.

Read the full Calabar Bean monograph & all interactions
Keep checking

Other Drugs & Calabar Bean

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

0Major
0Moderate
194Minor
2,635No known interaction
194 Minor 2,635 No interaction
Minor

194 interactions

Showing 60 of 194 minor interactions — see all 194 on the Calabar Bean page.

No interaction 2,635 drugs checked — show the list

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

Showing the 60 most looked-up of 2,635 medications checked with no known interaction — see the full Calabar Bean list.

See the full Calabar Bean interactions page
See every supplement checked against Methantheline Bromide, 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
Calabar Bean monograph › Uses, safety, and every drug interaction in one place Methantheline Bromide supplement interactions › Every supplement checked against Methantheline Bromide, 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 Calabar Bean and Methantheline Bromide Together: Common Questions

Can you take Calabar Bean with Methantheline Bromide?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Calabar Bean and Methantheline Bromide interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Methantheline Bromide and Calabar Bean?

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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.