Drug & supplement interaction

Goldthread + Fesoterodine Fumarate

Fesoterodine Fumarate brand name: Toviaz.

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

Goldthread has a moderate interaction with Fesoterodine Fumarate. 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 Fesoterodine Fumarate

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Fesoterodine Fumarate

Fesoterodine Fumarate 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

Here's the gist for Toviaz (fesoterodine): your body relies partly on an enzyme called CYP3A4 to clear it out. Berberine, the active compound in goldthread, may slow that enzyme down, at least based on early lab work. If it does, fesoterodine could linger longer and build up, which can amp up its usual antimuscarinic side effects, things like dry mouth, constipation, blurry vision, dizziness, or trouble fully emptying your bladder.

I want to be honest about the strength of this, though. It's theoretical right now and hasn't actually been reported in people, so I wouldn't lose sleep over it. Still, if you'd like to try goldthread, run it past your pharmacist or doctor first so they can keep an eye on how you're feeling.

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 644 moderate known drug interactions in our database — the Fesoterodine Fumarate one above is one of them. If you take anything else, check it against the full list below.

Moderate 644 No known interaction 2,186 (incl. Fesoterodine Fumarate)
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 Fesoterodine Fumarate

This page covers Goldthread only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fesoterodine Fumarate page lists 195 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: 9 major · 147 moderate · 39 minor.

From our pharmacist’s overview on the Fesoterodine Fumarate page

“Fesoterodine (Toviaz) calms an overactive bladder, and this list deserves genuine care, because nine of its 195 entries are rated major. Most of the supplements here change how your body clears the drug.”

Reviewed by 2 · Jul 18, 2026

Open the Fesoterodine Fumarate 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 Fesoterodine Fumarate 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 Fesoterodine Fumarate 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%

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

29 days ago today
Medication Fesoterodine Fumarate
Steady interest

#1,909 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
Medication

About Fesoterodine

What Is Fesoterodine Used For?

Brand name: Toviaz

Fesoterodine treats overactive bladder (OAB) in adults. That means symptoms like urge urinary incontinence (leaking with a sudden urge), urgency, and frequency.

Some products are also approved for neurogenic detrusor overactivity (NDO) in children 6 years and older who weigh more than 25 kg. This use is listed for Toviaz and for one fesoterodine fumarate film-coated extended-release tablet label. The other fesoterodine fumarate extended-release tablet label covers adult OAB only.

See full Fesoterodine drug information
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
644Moderate
0Minor
2,185No known interaction
644 Moderate 2,185 No interaction
Moderate

644 interactions

Showing 60 of 644 moderate interactions — see all 644 on the Goldthread page.

No interaction 2,185 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 2,185 medications checked with no known interaction — see the full Goldthread list.

See the full Goldthread interactions page
See every supplement checked against Fesoterodine Fumarate, 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 Fesoterodine Fumarate supplement interactions › Every supplement checked against Fesoterodine Fumarate, ranked by severity Fesoterodine 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 Goldthread and Fesoterodine Fumarate Together: Common Questions

Can you take Goldthread with Fesoterodine Fumarate?
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 Fesoterodine Fumarate 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 Fesoterodine Fumarate 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.