Drug & supplement interaction

Red Yeast Rice + Tamoxifen Citrate

Tamoxifen Citrate brand names: Nolvadex, Soltamox.

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

Red Yeast Rice has a moderate interaction with Tamoxifen Citrate. Theoretically, concomitant use might increase the risk of liver damage.

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

Red Yeast Rice and Tamoxifen Citrate

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Tamoxifen Citrate

Tamoxifen Citrate falls under HEPATOTOXIC DRUGS — the group Red Yeast Rice interacts with.

Theoretically, concomitant use might increase the risk of liver damage.
Red yeast rice contains varying levels of the drug lovastatin. Lovastatin can cause liver damage in some people. Some clinical research suggests that supplements containing red yeast rice might increase liver enzyme levels in some, but not all, participants. Cases of acute hepatitis have been associated with red yeast rice. Combining it with hepatotoxic drugs might further increase this risk.
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 concern when you pair red yeast rice with tamoxifen: both can put a little extra stress on your liver. Red yeast rice naturally contains lovastatin, a statin that occasionally raises liver enzymes or, rarely, triggers liver inflammation. Tamoxifen, on its own, can also affect the liver in some people. Stacking the two together could, in theory, add up.

I want to be honest about the strength of this, though. It's a theoretical caution based on how these substances behave, not proof that problems will happen. This isn't about red yeast rice changing how well tamoxifen fights breast cancer. Still, since tamoxifen is an important medicine, please check with your pharmacist or doctor before adding red yeast rice. Watch for warning signs like yellowing skin or eyes, dark urine, belly pain, or unusual tiredness.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Roselle H, Ekatan A, Tzeng J, et al. Symptomatic hepatitis associated with the use of herbal red yeast rice. Ann Intern Med 2008;149:516-7. PubMed
  2. Huang, J., Frohlich, J., and Ignaszewski, A. P. The impact of dietary changes and dietary supplements on lipid profile. Can J Cardiol 2011;27(4):488-505. PubMed
  3. Grieco, A., Miele, L., Pompili, M., Biolato, M., Vecchio, F. M., Grattagliano, I., and Gasbarrini, G. Acute hepatitis caused by a natural lipid-lowering product: when "alternative" medicine is no "alternative" at all. J Hepatol 2009;50(6):1273-1277. PubMed
  4. Lin, C. C., Li, T. C., and Lai, M. M. Efficacy and safety of Monascus purpureus Went rice in subjects with hyperlipidemia. Eur J Endocrinol 2005;153(5):679-686. PubMed
  5. Prescribing Information. Mevacor (lovastatin). Whitehouse Station, NJ: Merck & Co., Inc., February 2012.

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

Red Yeast Rice Also Interacts With Other Medications

Red Yeast Rice has 477 moderate known drug interactions in our database — the Tamoxifen Citrate one above is one of them. If you take anything else, check it against the full list below.

Moderate 477 No known interaction 2,353 (incl. Tamoxifen Citrate)
Taking anything else?

Check Another of Your Medications Against Red Yeast Rice

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

From our Q&A

Questions About Red Yeast Rice 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 Red Yeast Rice 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 Red Yeast Rice 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

One more smart check

Taking Red Yeast Rice as Part of a Dietary Supplement Product? Check It for Interactions

We hold 593 real supplement products containing Red Yeast Rice, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Red Yeast Rice. Your product may carry other ingredients that interact with Tamoxifen Citrate too, on top of Red Yeast Rice — 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 Red Yeast Rice 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 Red Yeast Rice
Top 25%

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

29 days ago today
Medication Tamoxifen Citrate
Top 10%

#163 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 Red Yeast Rice

What is Red Yeast Rice?

Red Yeast Rice
  • High cholesterol
  • Heart health
  • Metabolic syndrome
  • Statin alternative

Red yeast rice contains monacolin K, which is chemically identical to the prescription statin lovastatin, and it can lower LDL ('bad') cholesterol. Because of this, it carries the same risks as statin drugs, and the amount of active ingredient varies widely between products. Always talk to your pharmacist or doctor before using it, especially if you have liver problems or take other medicines.

Read the full Red Yeast Rice monograph & all interactions
Medication

About Tamoxifen

What Is Tamoxifen Used For?

Brand names: Nolvadex, Soltamox

Tamoxifen is used to treat metastatic breast cancer (breast cancer that has spread) in both women and men, and as adjuvant (after-surgery) therapy 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) — a very early, non-invasive form of breast cancer — tamoxifen is used after breast surgery and radiation to reduce the risk of developing invasive breast cancer. It is also approved to reduce the incidence of breast cancer in women who are at high risk but have not yet been diagnosed. Soltamox (oral solution) is specifically indicated for all of these uses in adult patients.

See full Tamoxifen drug information
Keep checking

Other Drugs & Red Yeast Rice

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

0Major
477Moderate
0Minor
2,352No known interaction
477 Moderate 2,352 No interaction
Moderate

477 interactions

Showing 60 of 477 moderate interactions — see all 477 on the Red Yeast Rice page.

No interaction 2,352 drugs checked — show the list

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

Showing the 60 most looked-up of 2,352 medications checked with no known interaction — see the full Red Yeast Rice list.

See the full Red Yeast Rice 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
Red Yeast Rice 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 Red Yeast Rice and Tamoxifen Citrate Together: Common Questions

Can you take Red Yeast Rice 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.
How serious is the Red Yeast Rice 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 Red Yeast Rice?

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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.