Drug & supplement interaction

Corydalis Yanhusuo + Tamoxifen Citrate

Tamoxifen Citrate brand names: Nolvadex, Soltamox.

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

Tamoxifen Citrate falls into 3 drug categories that Corydalis Yanhusuo can interact with; the most serious is rated moderate. Theoretically, Corydalis yanhusuo might increase serum levels of drugs metabolized by CYP2D6.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Corydalis Yanhusuo and Tamoxifen Citrate

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Corydalis Yanhusuo interacts with whole categories of medication. Tamoxifen Citrate falls into 3 of those categories, so it can interact with Corydalis Yanhusuo in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

1 of 3

Why this applies to Tamoxifen Citrate

Tamoxifen Citrate falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES — the group Corydalis Yanhusuo interacts with.

Theoretically, Corydalis yanhusuo might increase serum levels of drugs metabolized by CYP2D6.
Corydalis yanhusuo contains berberine. In vitro research and preliminary clinical evidence show that berberine can inhibit CYP2D6. Theoretically, Corydalis yanhusuo might also inhibit CYP2D6.
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 wrinkle with tamoxifen: it's actually a prodrug. Your body has to switch it on using an enzyme called CYP2D6, which turns tamoxifen into its active, cancer-fighting form (endoxifen). Corydalis yanhusuo contains compounds (like berberine) that may block that same CYP2D6 enzyme.

So in theory, the combination could mean your body makes less of the active form, which might make tamoxifen work less well at preventing or treating breast cancer. I want to be honest that this is a theoretical concern based on lab work, not proven in real patients. But because tamoxifen is so important, I'd play it safe. Please check with your oncologist or pharmacist before adding Corydalis.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chatterjee P, Franklin MR. Human cytochrome p450 inhibition and metabolic-intermediate complex formation by goldenseal extract and its methylenedioxyphenyl components. Drug Metab Dispos 2003;31:1391-7. PubMed
  2. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
  3. Hermann, R. and von, Richter O. Clinical evidence of herbal drugs as perpetrators of pharmacokinetic drug interactions. Planta Med 2012;78(13):1458-1477. PubMed
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

2 of 3

Tamoxifen Citrate also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, Corydalis yanhusuo might increase serum levels of drugs metabolized by CYP2C9.
Corydalis yanhusuo contains berberine. Preliminary clinical research shows that berberine can inhibit CYP2C9. Theoretically, Corydalis yanhusuo might also inhibit CYP2C9.
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 wrinkle with tamoxifen: it's actually a prodrug. Your body has to convert it into its active form (mostly through a different enzyme, CYP2D6, but CYP2C9 plays a role too) before it fights breast cancer cells. Corydalis contains berberine, which lab research suggests can block the CYP2C9 enzyme. In theory, slowing that pathway could nudge how much active drug you end up with.

I want to be honest about the strength here: this is purely theoretical, based on how the chemistry might behave, not on real patient studies. Still, because tamoxifen is a serious cancer medicine where you really want steady, reliable activation, I'd play it safe. Please check with your oncologist or pharmacist before adding corydalis rather than starting it on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

3 of 3

Tamoxifen Citrate also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, Corydalis yanhusuo might increase serum levels of drugs metabolized by CYP3A4.
Corydalis yanhusuo contains berberine. In vitro research and preliminary clinical research show that berberine moderately inhibits CYP3A4. Theoretically, Corydalis yanhusuo might also inhibit CYP3A4.
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 wrinkle with tamoxifen: it's actually a prodrug. Your body has to convert it into its active form (mostly through an enzyme called CYP2D6) for it to do its cancer-fighting job. The interaction we have on file is about Corydalis possibly slowing down a different enzyme, CYP3A4, which also plays a part in handling tamoxifen. In theory, blocking that pathway could shift tamoxifen levels a bit, though it's hard to predict exactly how the active drug ends up.

I want to be honest: this is theoretical, based on how the herb behaves in lab studies, not real-world cases. Still, tamoxifen is a serious medicine where you don't want surprises affecting how well it works or its side effects (hot flashes, clot risk). Please don't start Corydalis without running it by your oncologist or pharmacist first.

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
  2. Budzinski JW, Foster BC, Vandenhoek S, Arnason JT. An in vitro evaluation of human cytochrome P450 3A4 inhibition by selected commercial herbal extracts and tinctures. Phytomedicine 2000;7:273-82. PubMed
  3. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
  4. Hermann, R. and von, Richter O. Clinical evidence of herbal drugs as perpetrators of pharmacokinetic drug interactions. Planta Med 2012;78(13):1458-1477. 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

Corydalis Yanhusuo Also Interacts With Other Medications

Corydalis Yanhusuo has 1,159 moderate known drug interactions in our database — the Tamoxifen Citrate one above is among them. If you take anything else, check it against the full list below.

Moderate 1,159 No known interaction 1,671 (incl. Tamoxifen Citrate)
Taking anything else?

Check Another of Your Medications Against Corydalis Yanhusuo

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

From our Q&A

Questions About Corydalis Yanhusuo or Tamoxifen Citrate

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Corydalis Yanhusuo or Tamoxifen Citrate, 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 Tamoxifen Citrate

This page covers Corydalis Yanhusuo only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tamoxifen Citrate page lists 210 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 11 major · 166 moderate · 33 minor.

From our pharmacist’s overview on the Tamoxifen Citrate page

“Tamoxifen (Nolvadex, Soltamox) often stands between a breast cancer patient and a recurrence, so the stakes on this page run higher than usual. Eleven of the 210 supplements and herbs on file carry a major rating, and those eleven deserve your attention ahead of everything else.”

Reviewed by 2 · Jul 18, 2026

Open the Tamoxifen Citrate interaction page

How much people look this up

Where Corydalis Yanhusuo and Tamoxifen Citrate 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 Corydalis Yanhusuo
Top half

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

29 days ago today
Medication Tamoxifen Citrate
Top 5%

#116 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 Corydalis Yanhusuo

What is Corydalis Yanhusuo?

  • Pain relief
  • Menstrual cramps
  • Headache
  • Stress and sleep support
  • Stomach and abdominal discomfort

Corydalis yanhusuo is a traditional Chinese herb used mainly for pain. Some early laboratory and animal research suggests its compounds may affect pain and the nervous system, but high-quality human studies are limited, so its true benefits and long-term safety are not well established. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full Corydalis Yanhusuo monograph & all interactions
Medication

About Tamoxifen

What Is Tamoxifen Used For?

Brand names: Nolvadex, Soltamox

Tamoxifen is used to treat estrogen receptor-positive metastatic breast cancer in both women and men, and as follow-up (adjuvant) therapy after surgery for early-stage breast cancer in women. It also reduces the occurrence of cancer in the opposite breast when used as adjuvant therapy.

In women with ductal carcinoma in situ (DCIS — an early, non-invasive breast change) following surgery and radiation, tamoxifen lowers the risk of developing invasive breast cancer. It is also approved to reduce the risk of breast cancer in women who are at high risk but have not yet been diagnosed. Both Tamoxifen Citrate tablets and Soltamox oral solution share these indications.

See full Tamoxifen drug information
Keep checking

Other Drugs & Corydalis Yanhusuo

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

0Major
1,159Moderate
0Minor
1,670No known interaction
1,159 Moderate 1,670 No interaction
Moderate

1,159 interactions

Showing 60 of 1,159 moderate interactions — see all 1,159 on the Corydalis Yanhusuo page.

No interaction 1,670 drugs checked — show the list

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

Showing the 60 most looked-up of 1,670 medications checked with no known interaction — see the full Corydalis Yanhusuo list.

See the full Corydalis Yanhusuo interactions page
See every supplement checked against Tamoxifen Citrate, 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
Corydalis Yanhusuo monograph › Uses, safety, and every drug interaction in one place Tamoxifen Citrate supplement interactions › Every supplement checked against Tamoxifen Citrate, ranked by severity Tamoxifen 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 Corydalis Yanhusuo and Tamoxifen Citrate Together: Common Questions

Can you take Corydalis Yanhusuo with Tamoxifen Citrate?
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.
Why are there 3 interactions listed for Corydalis Yanhusuo and Tamoxifen Citrate?
Tamoxifen Citrate belongs to more than one drug category, and Corydalis Yanhusuo interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Corydalis Yanhusuo and Tamoxifen Citrate 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 Tamoxifen Citrate and Corydalis Yanhusuo?

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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.