Drug & supplement interaction

Goldthread + Belladonna, Ergotamine, Phenobarbital

Belladonna, Ergotamine, Phenobarbital brand name: Bellergal-S.

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

Goldthread has a moderate interaction with Belladonna, Ergotamine, Phenobarbital. There's very preliminary evidence that berberine, a constituent of goldthread, might inhibit cytochrome P450 3A4 (CYP3A4) enzyme.

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

Goldthread and Belladonna, Ergotamine, Phenobarbital

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Belladonna, Ergotamine, Phenobarbital

Belladonna, Ergotamine, Phenobarbital falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Goldthread interacts with.

There's very preliminary evidence that berberine, a constituent of goldthread, might inhibit cytochrome P450 3A4 (CYP3A4) enzyme. So far, this interaction has not been reported in humans. However, watch for an increase in the levels of drugs metabolized by CYP3A4 in patients taking goldthread. Some drugs metabolized by CYP3A4 include lovastatin (Mevacor), clarithromycin (Biaxin), indinavir (Crixivan), sildenafil (Viagra), triazolam (Halcion), and numerous others. Use goldthread cautiously or avoid in patients taking these drugs.
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 pill (sold as Bellergal-S) mixes three active ingredients. The one I'd watch most closely here is ergotamine, which your liver clears using an enzyme called CYP3A4. Berberine, the main compound in goldthread, may gently slow that enzyme down in lab studies. If it did the same in you, ergotamine could build up a bit, and that's the concern, because too much ergotamine can cause nausea, cold or tingling hands and feet, leg cramps, or in rare cases reduced blood flow.

Now, the honest part: this is theoretical, based on lab work, not on real reports in people. So I'm not raising an alarm, just suggesting caution. Please run goldthread past your pharmacist or doctor before combining the two.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wu X, Li Q, Xin H, Yu A, Zhong M. Effects of berberine on the blood concentration of cyclosporin A in renal transplanted recipients: clinical and pharmacokinetic study. Eur J Clin Pharmacol 2005;61:567-72. 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

Goldthread Also Interacts With Other Medications

Goldthread has 642 moderate known drug interactions in our database — the Belladonna, Ergotamine, Phenobarbital one above is one of them. If you take anything else, check it against the full list below.

Moderate 642 No known interaction 2,188 (incl. Belladonna, Ergotamine, Phenobarbital)
Taking anything else?

Check Another of Your Medications Against Goldthread

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

Everything else you take

See Every Supplement That Interacts With Belladonna, Ergotamine, Phenobarbital

This page covers Goldthread only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Belladonna, Ergotamine, 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 Belladonna, Ergotamine, Phenobarbital page

“Bellergal-S packs three drugs into one tablet, and its supplement list earns real respect before you mix in anything else. Phenobarbital is a sedating barbiturate, belladonna adds drying anticholinergic effects, and ergotamine constricts blood vessels, so this combination collects interactions from several directions at once.”

Reviewed by 2 · Jul 18, 2026

Open the Belladonna, Ergotamine, Phenobarbital interaction page

One more smart check

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

We hold 25 real supplement products containing Goldthread, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Goldthread. Your product may carry other ingredients that interact with Belladonna, Ergotamine, Phenobarbital too, on top of Goldthread — 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 Goldthread and Belladonna, Ergotamine, 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 Goldthread
Top 25%

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

29 days ago today
Medication Belladonna, Ergotamine, Phenobarbital
Top half

#751 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 Goldthread

What is Goldthread?

Goldthread
  • Digestive upset and diarrhea
  • Mouth sores and sore throat
  • Inflammation
  • Antimicrobial (fighting germs)
  • Blood sugar support
  • Skin and eye complaints

Goldthread is a traditional Chinese and East Asian herb whose root is rich in berberine, a compound being studied for blood sugar, cholesterol, and antimicrobial effects. Strong human evidence for goldthread itself is limited, and it should be avoided in pregnancy and breastfeeding. Talk with your pharmacist or doctor before using it, especially if you take other medicines.

Read the full Goldthread monograph & all interactions
Keep checking

Other Drugs & Goldthread

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

0Major
642Moderate
0Minor
2,187No known interaction
642 Moderate 2,187 No interaction
Moderate

642 interactions

Showing 60 of 642 moderate interactions — see all 642 on the Goldthread page.

No interaction 2,187 drugs checked — show the list

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

Showing the 60 most looked-up of 2,187 medications checked with no known interaction — see the full Goldthread list.

See the full Goldthread interactions page
See every supplement checked against Belladonna, Ergotamine, 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
Goldthread monograph › Uses, safety, and every drug interaction in one place Belladonna, Ergotamine, Phenobarbital supplement interactions › Every supplement checked against Belladonna, Ergotamine, 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 Goldthread and Belladonna, Ergotamine, Phenobarbital Together: Common Questions

Can you take Goldthread with Belladonna, Ergotamine, 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.
How serious is the Goldthread and Belladonna, Ergotamine, 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 Belladonna, Ergotamine, Phenobarbital and Goldthread?

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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.