Drug & supplement interaction

Eleuthero + Tamoxifen Citrate

Tamoxifen Citrate brand names: Nolvadex, Soltamox.

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

Tamoxifen Citrate falls into 4 drug categories that Eleuthero can interact with; the most serious is rated moderate. Theoretically, eleuthero might increase levels of drugs metabolized by CYP2C9.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions4
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Eleuthero and Tamoxifen Citrate

These two interact in 4 distinct ways. Each one is explained separately below.

Why Are There 4 Interactions?

Eleuthero interacts with whole categories of medication. Tamoxifen Citrate falls into 4 of those categories, so it can interact with Eleuthero in 4 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

1 of 4

Why this applies to Tamoxifen Citrate

Tamoxifen Citrate falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Eleuthero interacts with.

Theoretically, eleuthero might increase levels of drugs metabolized by CYP2C9.
In vitro and animal research suggest that standardized extracts of eleuthero might inhibit CYP2C9. This effect has not been reported in humans.
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 tamoxifen and eleuthero. Lab and animal studies hint that eleuthero might slow down a liver enzyme called CYP2C9, which is one of the enzymes that helps process tamoxifen. In theory, blocking that enzyme could let tamoxifen levels drift a bit higher, which might mean more of its usual side effects like hot flashes, nausea, leg cramps, or fluid retention.

The important part: this has only been seen in test tubes and animals, never confirmed in people, so it's a theoretical concern rather than a proven problem. Tamoxifen also relies on other enzymes (mainly CYP2D6 and CYP3A4) to work properly, so the picture is complicated. Since tamoxifen is a serious medication, please run any eleuthero use past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Harkey MR, Henderson GL, Zhou L, et al. Effects of Siberian ginseng (Eleutherococcus senticosus) on c-DNA-expressed P450 drug metabolizing enzymes. Alt Ther 2001;7:S14.
Moderate

P-GLYCOPROTEIN SUBSTRATES

2 of 4

Tamoxifen Citrate also falls under P-GLYCOPROTEIN SUBSTRATES.

Theoretically, eleuthero might increase levels of P-glycoprotein substrates.
In vitro research suggests that eleuthero can inhibit the multi-drug transporter protein, P-glycoprotein. However, it is too soon to tell if this is clinically important. This interaction has not been reported in humans.
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 tamoxifen: there's a transporter protein in your body called P-glycoprotein that helps shuttle certain drugs out of cells and back into your gut and urine. Lab studies hint that eleuthero may slow this transporter down. If that happened with tamoxifen, slightly more of it could stay in your system, which in theory might mean a bit more of its usual effects like hot flashes, leg cramps, or nausea.

I want to be honest about the strength of this, though. It comes only from test-tube research, and it has never actually been reported in real people. So this is more of a theoretical caution than a proven problem. Because tamoxifen is such an important breast cancer medicine, I'd still mention any eleuthero supplement to your oncologist or pharmacist before adding it, just so everyone's on the same page.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Takahashi T, Kaku T, Sato T, et al. Effects of Acanthopanax senticosus HARMS extract on drug transport in human intestinal cell line Caco-2. J Nat Med. 2010;64(1):55-62. PubMed
  2. Freye E, GLeske J. Siberian ginseng results in beneficial effects on glucose metabolism in diabetes type 2 patients: a double blind placebo-controlled study in comparison to panax ginseng. Int J Clin Nutr. 2013;1(1):11-17.
Minor

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

3 of 4

Tamoxifen Citrate also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, eleuthero might increase levels of drugs metabolized by CYP2D6.
In vitro and animal research suggest that standardized extracts of eleuthero might inhibit CYP2D6. However, research in healthy human volunteers has found that taking eleuthero 485 mg twice daily for 14 days does not inhibit CYP2D6 drug metabolism.
Severity Minor Likelihood Unlikely Evidence B

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's something worth knowing about tamoxifen: it's actually a prodrug. Your body has to convert it into its active form (endoxifen) using an enzyme called CYP2D6. That active form is what does the real work against breast cancer cells. So anything that slows down CYP2D6 could, in theory, leave you with less of the active drug.

Lab and animal studies hinted that eleuthero might block CYP2D6, which could mean weaker tamoxifen activity. But here's the reassuring part: when researchers actually tested eleuthero in healthy people, it did not meaningfully affect this enzyme. So this concern is mostly theoretical and considered unlikely. Still, because tamoxifen is so important, I'd run any eleuthero use past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Harkey MR, Henderson GL, Zhou L, et al. Effects of Siberian ginseng (Eleutherococcus senticosus) on c-DNA-expressed P450 drug metabolizing enzymes. Alt Ther 2001;7:S14.
  2. Donovan JL, DeVane CL, Chavin KD, et al. Siberian Ginseng (Eleutheroccus senticosus) Effects on CYP2D6 and CYP3A4 Activity in Normal Volunteers. Drug Metab Dispos 2003;31:519-22.. PubMed
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

4 of 4

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

Theoretically, eleuthero might increase levels of drugs metabolized by CYP3A4.
In vitro and animal research suggest that standardized extracts of eleuthero might inhibit CYP3A4. However, research in healthy human volunteers has found that taking eleuthero 485 mg twice daily for 14 days does not inhibit CYP3A4 drug metabolism.
Severity Minor Likelihood Unlikely Evidence B

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist for tamoxifen and eleuthero. Tamoxifen is actually a prodrug, meaning your body has to convert it into its active form (mainly through enzymes like CYP2D6 and CYP3A4) before it can do its job against breast cancer. The concern on file is that eleuthero might block CYP3A4. In a test tube and in animals, eleuthero slowed this enzyme, which could in theory shift how tamoxifen is processed.

The good news: in actual healthy people, eleuthero at 485 mg twice daily did not change CYP3A4 activity. So this interaction is largely theoretical and rated minor and unlikely. Still, because tamoxifen is so important for your treatment, please run any eleuthero supplement past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Harkey MR, Henderson GL, Zhou L, et al. Effects of Siberian ginseng (Eleutherococcus senticosus) on c-DNA-expressed P450 drug metabolizing enzymes. Alt Ther 2001;7:S14.
  2. Donovan JL, DeVane CL, Chavin KD, et al. Siberian Ginseng (Eleutheroccus senticosus) Effects on CYP2D6 and CYP3A4 Activity in Normal Volunteers. Drug Metab Dispos 2003;31:519-22.. 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

Eleuthero Also Interacts With Other Medications

Eleuthero has 678 moderate, 461 minor 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 678 Minor 461 No known interaction 1,691 (incl. Tamoxifen Citrate)
Taking anything else?

Check Another of Your Medications Against Eleuthero

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

From our Q&A

Questions About Eleuthero 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 Eleuthero 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 Eleuthero 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 Eleuthero as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,795 real supplement products containing Eleuthero, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Eleuthero. Your product may carry other ingredients that interact with Tamoxifen Citrate too, on top of Eleuthero — 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 Eleuthero 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 Eleuthero
Top 5%

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

29 days ago today
Medication Tamoxifen Citrate
Top 10%

#214 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 Eleuthero

What is Eleuthero?

Eleuthero
  • Fatigue and low energy
  • Physical and athletic performance
  • Stress resistance (adaptogen)
  • Immune support
  • Mental focus and alertness

Eleuthero is an herb traditionally used as an 'adaptogen' to fight fatigue, boost energy, and help the body handle stress. The scientific evidence behind these uses is limited and mixed, so it should not replace proven treatments. It is generally well tolerated short-term, but pregnant and breastfeeding people and those with certain conditions should avoid it or check with a healthcare provider first.

Read the full Eleuthero 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 & Eleuthero

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

0Major
678Moderate
461Minor
1,690No known interaction
678 Moderate 461 Minor 1,690 No interaction
Moderate

678 interactions

Showing 60 of 678 moderate interactions — see all 678 on the Eleuthero page.

Minor

461 interactions

Showing 60 of 461 minor interactions — see all 461 on the Eleuthero page.

No interaction 1,690 drugs checked — show the list

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

Showing the 60 most looked-up of 1,690 medications checked with no known interaction — see the full Eleuthero list.

See the full Eleuthero 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
Eleuthero 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 Eleuthero and Tamoxifen Citrate Together: Common Questions

Can you take Eleuthero 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 4 interactions listed for Eleuthero and Tamoxifen Citrate?
Tamoxifen Citrate belongs to more than one drug category, and Eleuthero 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 Eleuthero 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 Eleuthero?

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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.