Drug & supplement interaction

Calabar Bean + Doxylamine Succinate

Doxylamine Succinate brand name: Unisom.

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

Calabar Bean has a minor interaction with Doxylamine Succinate. 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 Doxylamine Succinate

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

Minor

ANTICHOLINERGIC DRUGS

Why this applies to Doxylamine Succinate

Doxylamine Succinate 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 basic idea: doxylamine (the sleep aid in Unisom) works partly by blocking acetylcholine, a nerve messenger. Calabar bean does the opposite. It contains physostigmine, which makes acetylcholine pile up. So in theory, these two could work against each other, and you might notice your doxylamine not making you as drowsy or it wearing off sooner.

I want to be straight with you, though. This is a theoretical concern based on how the chemicals behave, not on real cases, and the interaction is rated minor and unlikely. The much bigger issue is that Calabar bean itself is genuinely poisonous and is not a safe supplement to take at all. Please don't use it, and check in with your pharmacist or doctor about anything you're combining.

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 Doxylamine Succinate 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. Doxylamine Succinate)
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.

From our Q&A

Questions About Calabar Bean or Doxylamine Succinate

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

This page covers Calabar Bean only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Doxylamine Succinate page lists 52 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 · 38 moderate · 11 minor.

From our pharmacist’s overview on the Doxylamine Succinate page

“Someone reaching for doxylamine succinate (Unisom) to fall asleep is often the same person browsing the supplement aisle, and that pairing deserves genuine care here. Doxylamine is a strongly anticholinergic antihistamine, meaning it dries you out, fogs thinking, and slows digestion, and 30 of the 52 flagged ingredients pile more of th…”

Reviewed by 2 · Jul 18, 2026

Open the Doxylamine Succinate interaction page

How much people look this up

Where Calabar Bean and Doxylamine Succinate 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

#1,211 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Doxylamine Succinate
Steady interest

#1,604 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
Medication

About Diphenhydramine

What Is Diphenhydramine Used For?

Brand name: Unisom

Diphenhydramine temporarily relieves symptoms of hay fever, other upper respiratory allergies, and the common cold — including runny nose, sneezing, itchy or watery eyes, and itching of the nose or throat.

After Bite Xtra gel is formulated for topical use and is approved to temporarily relieve pain and itching from minor burns, minor cuts and scrapes, insect bites, minor skin irritations, and rashes from poison ivy, poison oak, and poison sumac.

See full Diphenhydramine drug information
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 Doxylamine Succinate, 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 Doxylamine Succinate supplement interactions › Every supplement checked against Doxylamine Succinate, ranked by severity Diphenhydramine 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 Calabar Bean and Doxylamine Succinate Together: Common Questions

Can you take Calabar Bean with Doxylamine Succinate?
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 Doxylamine Succinate 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 Doxylamine Succinate 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.