Herb & supplement monograph

Calabar Bean Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Calabar Bean interacts with medications. The heart of this page is the interaction list — every drug Calabar Bean is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Calabar Bean is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Calabar Bean Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Calabar Bean drug interaction appears low for most people. Every interaction on record is rated minor, with none reaching moderate or major severity.

Interactions deserving the most attention

The one group worth knowing about is anticholinergic drugs, a class used for conditions such as overactive bladder, motion sickness, and some breathing problems. In theory, a natural chemical in calabar bean called physostigmine could work against these medicines and reduce their effects. That said, this concern comes from lab findings rather than human studies, and the evidence actually suggests it does not play out in people. No interaction in this profile is backed by strong human evidence.

What the rest of the list means

Calabar bean appears alongside a long list of medications, but that number is misleading on its own. Nearly all of these entries trace back to the same single theoretical mechanism, applied across the many individual drugs with anticholinergic activity. A long list here reflects one weak, unproven concern repeated many times, not many separate proven risks.

Check your medications against Calabar Bean

Based on HelloPharmacist’s Calabar Bean interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Calabar Bean

195 medications have a known interaction with Calabar Bean, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
AcepromazineAtravet› Acetaminophen, Caffeine, Chlorpheniramine, Hydrocodone, PhenylephrineHycomine Compound› Acetaminophen, Caffeine, PyrilamineMidol Max Strength Menstrual› Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HbrVicks Formula 44M Cough, Cold & Flu Relief› Acetaminophen, Chlorpheniramine, Codeine, PhenylephrineColrex› Acetaminophen, Chlorpheniramine, DextromethorphanCoricidin II Extra Strength Cold and Flu› Acetaminophen, Chlorpheniramine, Dextromethorphan HydrobromideCoricidin HBP Maximum Strength Flu› Acetaminophen, Chlorpheniramine, Dextromethorphan, PhenylpropanolamineMulti Symptom Cold Relief› Acetaminophen, Chlorpheniramine, Dextromethorphan, PseudoephedrineChildren's Tylenol Cold Plus Cough, Tylenol Cold Ex Strength› Acetaminophen, Chlorpheniramine, Guaifenesin, Phenylephrine, SalicylamideRhinogesic GG› Acetaminophen, Chlorpheniramine, PhenylephrineAlka-Seltzer PLUS, Histex SR, Protid› Acetaminophen, Chlorpheniramine, Phenylephrine, SalicylamideRhinogesic, Rhinogesic JR› Acetaminophen, Chlorpheniramine, PhenylpropanolamineAlumadrine, Conex, Sinadrin Max Strength, Sinulin› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, OpiumHista-Derfule› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, PhenyltoloxamineNorel Plus› Acetaminophen, Chlorpheniramine, PseudoephedrineAlka-Seltzer PLUS Liquid Gels, Children's Tylenol Cold, Codimal, Comtrex, Extra Strength Tylenol Allergy Sinus, Lorsin +3 more› Acetaminophen, Codeine, DoxylamineMersyndol› Acetaminophen, Dextromethorphan, Doxylamine, PseudoephedrineVicks NyQuil› Acetaminophen, Dextromethorphan, Phenylpropanolamine, PyrilamineTheracaps› Acetaminophen, DiphenhydramineTylenol PM, Tylenol PM Ex Strength› Acetaminophen, Diphenhydramine, PseudoephedrineChildren's Tylenol Allergy, Cold Control, Contac Night Allergy Relief› Acetaminophen, Doxylamine, PseudoephedrineEx Strength Tylenol Sinus Nighttime› Acetaminophen, Pamabrom, PyrilamineMidol Max Strength PMS, Pamprin, Pamprin ES› Acetaminophen, Phenylephrine, ChlorpheniramineSuper Cold Tabs› Aclidinium BromideTudorza Pressair› Aclidinium Bromide, Formoterol Fumarate DihydrateDuaklir Pressair› Aerosphere Budesonide, Formoterol Fumarate, GlycopyrrolateBreztri› AmantadineGocovri, Osmolex ER, Symmetrel› AminoglutethimideCytadren› AmitriptylineElavil›
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Calabar Bean combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Calabar Bean affects

Every type of medication (drug category) Calabar Bean is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 1 drug category Calabar Bean interacts with
Anticholinergic Drugs
Anticholinergic Drugs

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.

Likelihood Unlikely Evidence D
Monograph

Calabar Bean: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

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.

Calabar Bean
Scientific name
Physostigma venenosum
Family
Fabaceae
Part used
Seeds (beans)
Common forms
Not available as a safe consumer supplement; historically the seed and its extracts were used, and the alkaloid physostigmine is used in prescription medicines
People commonly use it for
  • 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

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallBest avoided

The raw bean is poisonous and can cause severe, even fatal, poisoning.

PregnancyUnsafe

When used orally; avoid using.

Read the full pregnancy detail
BreastfeedingUnsafe

When used orally; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Calabar bean comes from a climbing plant called Physostigma venenosum, which grows in the warm, tropical regions of West Africa. The plant produces large, dark, bean-like seeds that are extremely poisonous.

In the past, these beans were most famous for their use in 'trial by ordeal' ceremonies. A person accused of a crime was forced to eat the bean. People believed that an innocent person would survive while a guilty person would die — a tragic and dangerous practice that simply reflected how poisonous the seed is.

The bean is best known to modern medicine because it contains physostigmine, a chemical that scientists isolated and later turned into a regulated prescription drug. The whole bean itself is not used as a dietary supplement and should not be taken.

How it works

The main active compound in Calabar bean is physostigmine, which belongs to a group of chemicals called cholinesterase inhibitors.

Normally, your body uses an enzyme to break down a chemical messenger called acetylcholine. Physostigmine blocks that enzyme, so acetylcholine builds up. This overstimulates nerves and muscles throughout the body, including the heart, glands, gut, and lungs.

In tiny, controlled medical doses this effect can be useful. But in the amounts found in a whole bean, this same mechanism causes dangerous overstimulation, leading to symptoms like heavy drooling, sweating, slow heart rate, breathing trouble, and muscle paralysis.

Effectiveness

Does Calabar Bean work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 4 uses evaluated
4 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.

For Calabar Bean, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 4 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Cholera
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral calabar bean for cholera, there is insufficient reliable information about the clinical effects of calabar bean for this purpose.

Insufficient Reliable Evidence To Rate Constipation
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral calabar bean for constipation, there is insufficient reliable information about the clinical effects of calabar bean for this purpose.

Insufficient Reliable Evidence To Rate Epilepsy
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral calabar bean for epilepsy, there is insufficient reliable information about the clinical effects of calabar bean for this purpose.

Insufficient Reliable Evidence To Rate Tetanus
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral calabar bean for tetanus, there is insufficient reliable information about the clinical effects of calabar bean for this purpose.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Calabar bean is poisonous and should not be eaten or used as a supplement. Even small amounts can cause serious, life-threatening poisoning.

This warning applies to everyone, but the danger is especially high for children, older adults, and anyone with heart, breathing, or nervous system conditions. There is no safe home method to prepare or dose the bean.

Pregnancy and breastfeeding: Avoid completely. The bean is toxic and could harm both the parent and the baby. Do not use it during pregnancy or while breastfeeding under any circumstances.

If you need a cholinesterase-inhibitor medication, only the purified, prescription form (physostigmine) given and monitored by a healthcare provider should ever be used.

Side effects

Eating Calabar bean can cause severe poisoning. Reported effects include:

  • Excessive salivation (drooling) and sweating
  • Nausea, vomiting, and diarrhea
  • Watery eyes and very small (pinpoint) pupils
  • Slow or irregular heartbeat and low blood pressure
  • Confusion, weakness, and muscle twitching
  • Difficulty breathing and muscle paralysis

In serious poisoning, these effects can lead to collapse and death. If someone has eaten Calabar bean or is showing these symptoms, treat it as a medical emergency and seek help immediately (call emergency services or a poison control center).

Calabar Bean: Reported Adverse Effects

Documented safety reports on Calabar Bean from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, calabar bean can be unsafe. Physostigmine, a constituent of calabar bean, can cause cholinergic crisis, including death.

Most Common Adverse Effects:

Oral: Bradycardia, diarrhea, miosis, hypertension, hypotension, salivation, sweating, tachycardia, vomiting.

Serious Adverse Effects (Rare):

Oral: Confusion, coma, muscle weakness, paralysis, seizures.

Reports by condition
Diarrhea Other

Orally, physostigmine, a constituent of calabar bean, can cause cholinergic crisis, including paralysis, coma, and death. Other symptoms of cholinergic crisis may include bradycardia, confusion, diarrhea, miosis, muscle weakness, salivation, sweating, and vomiting.

  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
Diarrhea Gastrointestinal

Orally, calabar bean can cause diarrhea and vomiting.

  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
Hypertension Cardiovascular

Orally, calabar bean can cause bradycardia, tachycardia, hypotension, and hypertension.

  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no safe or established dose of Calabar bean for self-care, and it should not be taken as a supplement. The bean is poisonous, and the amount of physostigmine it contains can vary, making any home use extremely risky.

The only proper medical use of this plant's active compound is the regulated prescription drug physostigmine, which a doctor doses precisely and monitors closely. Never attempt to use the bean yourself. If you have questions, talk to a pharmacist or doctor.

Pregnancy & Breastfeeding

Calabar Bean & Pregnancy

Unsafe

When used orally; avoid using.

  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.

Calabar Bean & Breastfeeding

Unsafe

When used orally; avoid using.

  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 2 references that drive our Calabar Bean monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
Keep reading

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.

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

Pharmacist Counseling Corner

Calabar Bean: Common Questions

What is Calabar Bean used for, and does it work?
People use Calabar Bean for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Calabar Bean interact with prescription medications?
Yes. We list 195 medications with a known interaction with Calabar Bean. Use the checker above to see how Calabar Bean interacts with a specific drug.
How are Calabar Bean interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Calabar Bean with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Calabar Bean interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
Is Calabar Bean safe to take?
No. The whole bean is poisonous and can cause severe, even fatal, poisoning. It is not a safe dietary supplement and should not be eaten.
What is Calabar Bean used for?
Historically it was used in 'ordeal' rituals and folk medicine, and it is the natural source of the prescription drug physostigmine. It has no proven, safe use as a supplement today.
Can I take Calabar Bean while pregnant or breastfeeding?
No. The bean is toxic and should be completely avoided during pregnancy and breastfeeding to protect both you and your baby.
What should I do if someone eats a Calabar Bean?
Treat it as a medical emergency. Call your local poison control center or emergency services right away, as poisoning can become serious very quickly.

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

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