Drug & supplement interaction

European Barberry + Demecarium

Demecarium brand name: Humorsol.

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

European Barberry has a moderate interaction with Demecarium. Theoretically, taking European barberry with cholinergic drugs might decrease the effects of cholinergic drugs.

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

European Barberry and Demecarium

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

Moderate

CHOLINERGIC DRUGS

Why this applies to Demecarium

Demecarium falls under CHOLINERGIC DRUGS — the group European Barberry interacts with.

Theoretically, taking European barberry with cholinergic drugs might decrease the effects of cholinergic drugs.
In vitro evidence suggests that European barberry might have anticholinergic properties.
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

Demecarium (Humorsol) is a cholinergic eye drop. It works by boosting your body's own acetylcholine, which keeps the pupil tight and helps drain fluid to lower eye pressure in glaucoma. Some lab studies hint that European barberry may have mild anticholinergic activity, meaning it could push in the opposite direction. In theory, that might slightly blunt how well demecarium controls your eye pressure.

I want to be honest here: this is a theoretical concern based only on test-tube data, not real patient reports. With an eye drop, very little reaches the rest of the body, so a meaningful clash is unlikely. Still, since glaucoma control matters, mention any barberry or berberine supplement to your eye doctor or pharmacist before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Shamsa F, Ahmadiani A, Khosrokhavar R. Antihistaminic and anticholinergic activity of barberry fruit (Berberis vulgaris) in the guinea-pig ileum. J Ethnopharmacol 1999;64:161-6. 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

European Barberry Also Interacts With Other Medications

European Barberry has 1,209 moderate known drug interactions in our database — the Demecarium one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,209 No known interaction 1,621 (incl. Demecarium)
Taking anything else?

Check Another of Your Medications Against European Barberry

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

Everything else you take

See Every Supplement That Interacts With Demecarium

This page covers European Barberry only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Demecarium page lists 39 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Arenaria Rubra (moderate), Bacopa (moderate), Bael (moderate) and Betel Nut (moderate).

By severity: 1 major · 28 moderate · 10 minor.

From our pharmacist’s overview on the Demecarium page

“Most people using demecarium (Humorsol) eye drops for glaucoma are older adults, often the same people reaching for memory supplements like huperzine A and bacopa, and those are what this list flags. Demecarium boosts acetylcholine, and 21 of the 39 supplements on file can add more of the same, raising the risk of cholinergic side effe…”

Reviewed by 2 · Jul 18, 2026

Open the Demecarium interaction page

One more smart check

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

We hold 2 real supplement products containing European Barberry, each one broken down to its full ingredient list — and combination products often carry several ingredients besides European Barberry. Your product may carry other ingredients that interact with Demecarium too, on top of European Barberry — 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 European Barberry and Demecarium 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 European Barberry
Steady interest

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

29 days ago today
Medication Demecarium
Top half

#787 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 European Barberry

What is European Barberry?

European Barberry
  • Digestive upset
  • Antimicrobial support
  • Blood sugar support
  • Cholesterol and metabolic support
  • Skin conditions

European barberry is a shrub whose root, bark, and berries contain berberine, a bitter plant alkaloid that has been studied mostly in isolated form. Some early research on berberine is promising for blood sugar and cholesterol, but high-quality evidence for the whole barberry herb is limited. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full European Barberry monograph & all interactions
Keep checking

Other Drugs & European Barberry

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

0Major
1,209Moderate
0Minor
1,620No known interaction
1,209 Moderate 1,620 No interaction
Moderate

1,209 interactions

Showing 60 of 1,209 moderate interactions — see all 1,209 on the European Barberry page.

No interaction 1,620 drugs checked — show the list

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

Showing the 60 most looked-up of 1,620 medications checked with no known interaction — see the full European Barberry list.

See the full European Barberry interactions page
See every supplement checked against Demecarium, 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
European Barberry monograph › Uses, safety, and every drug interaction in one place Demecarium supplement interactions › Every supplement checked against Demecarium, 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 European Barberry and Demecarium Together: Common Questions

Can you take European Barberry with Demecarium?
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.
How serious is the European Barberry and Demecarium 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 Demecarium and European Barberry?

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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.