Drug & supplement interaction

Hibiscus Sabdariffa + Tamoxifen Citrate

Tamoxifen Citrate brand names: Nolvadex, Soltamox.

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

Tamoxifen Citrate falls into 3 drug categories that Hibiscus Sabdariffa can interact with; the most serious is rated minor. Theoretically, Hibiscus sabdariffa extract might reduce the metabolism of CYP2D6 substrates.

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

Hibiscus Sabdariffa and Tamoxifen Citrate

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

Why Are There 3 Interactions?

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

Minor

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 Hibiscus Sabdariffa interacts with.

Theoretically, Hibiscus sabdariffa extract might reduce the metabolism of CYP2D6 substrates.
In vitro research shows that Hibiscus sabdariffa calyx extract inhibits CYP2D6. This interaction has not been reported in humans.
Severity Minor 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 something interesting about tamoxifen: it's actually a prodrug. Your body uses an enzyme called CYP2D6 to convert it into its active, cancer-fighting form (called endoxifen). So anything that slows down that enzyme could mean less of the active medicine is made, which might make tamoxifen work less well.

In a lab dish, concentrated hibiscus extract blocked CYP2D6. But here's the important part: this has never been seen in actual people, and it's only a theoretical concern based on test-tube data. A cup or two of tart hibiscus tea is very unlikely to cause a problem. To be safe, I'd skip concentrated hibiscus supplements while on tamoxifen and run it by your pharmacist or oncologist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Johnson SS, Oyelola FT, Ari T, Juho H. In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms. Afr J Tradit Complement Altern Med. 2013 Apr 12;10(3):533-40.
Minor

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

2 of 3

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

Theoretically, Hibiscus sabdariffa extract might reduce the metabolism of CYP2C9 substrates.
In vitro research shows that Hibiscus sabdariffa calyx extract inhibits CYP2C9. This interaction has not been reported in humans.
Severity Minor 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 with hibiscus and tamoxifen. Lab studies (done in test tubes, not people) suggest concentrated hibiscus extract may slow down an enzyme called CYP2C9. Tamoxifen leans partly on that enzyme as it gets processed by the body, so in theory blocking it could let a bit more of the drug linger. That might nudge up familiar tamoxifen effects like hot flashes, leg swelling, or mood changes.

I want to be honest though: this has never actually been reported in humans, and it's rated as a minor, theoretical concern. A cup or two of tart hibiscus tea is unlikely to cause trouble. Concentrated capsules are where I'd be more careful. Since tamoxifen is such an important medicine, just run any hibiscus supplement past your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Johnson SS, Oyelola FT, Ari T, Juho H. In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms. Afr J Tradit Complement Altern Med. 2013 Apr 12;10(3):533-40.
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

3 of 3

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

Theoretically, Hibiscus sabdariffa extract might reduce the metabolism of CYP3A4 substrates.
In vitro research shows that Hibiscus sabdariffa calyx extract inhibits CYP3A4. This interaction has not been reported in humans.
Severity Minor 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 with hibiscus and your tamoxifen. In lab dish studies, hibiscus extract slowed down an enzyme called CYP3A4, which is one of the enzymes your body uses to process tamoxifen. In theory, blocking that enzyme could let a bit more tamoxifen build up. The thing is, this has only been seen in a test tube, never actually in people, so it's a theoretical concern rather than a proven problem.

If anything did happen, you might notice more of tamoxifen's usual effects, like hot flashes, nausea, or fatigue. A cup of tart hibiscus tea now and then is unlikely to matter. Concentrated hibiscus supplements are the bigger question mark, so I'd run those by your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Johnson SS, Oyelola FT, Ari T, Juho H. In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms. Afr J Tradit Complement Altern Med. 2013 Apr 12;10(3):533-40.

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

Hibiscus Sabdariffa Also Interacts With Other Medications

Hibiscus Sabdariffa has 2 major, 266 moderate, 820 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.

Major 2 Moderate 266 Minor 820 No known interaction 1,742 (incl. Tamoxifen Citrate)
Taking anything else?

Check Another of Your Medications Against Hibiscus Sabdariffa

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

From our Q&A

Questions About Hibiscus Sabdariffa 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 Hibiscus Sabdariffa 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 Hibiscus Sabdariffa 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 Hibiscus Sabdariffa 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 Hibiscus Sabdariffa
Top half

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

29 days ago today
Medication Tamoxifen Citrate
Top 5%

#126 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 Hibiscus Sabdariffa

What is Hibiscus Sabdariffa?

Hibiscus Sabdariffa
  • High blood pressure
  • Heart and cholesterol health
  • Digestive upset
  • Antioxidant support
  • Fever and general wellness

Hibiscus sabdariffa is a tart, cranberry-flavored plant most often consumed as a tea, and its best-studied use is for mildly lowering blood pressure. Evidence for other uses is limited, and while hibiscus tea is generally well tolerated in food amounts, concentrated supplements should be used cautiously and avoided in pregnancy. Talk to your pharmacist or doctor before using it for a medical condition.

Read the full Hibiscus Sabdariffa 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 Tamoxifen Citrate NDC codes and packages
Keep checking

Other Drugs & Hibiscus Sabdariffa

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

2Major
266Moderate
820Minor
1,741No known interaction
2 Major 266 Moderate 820 Minor 1,741 No interaction
Major

2 interactions

Moderate

266 interactions

Showing 60 of 266 moderate interactions — see all 266 on the Hibiscus Sabdariffa page.

Minor

820 interactions

Showing 60 of 820 minor interactions — see all 820 on the Hibiscus Sabdariffa page.

No interaction 1,741 drugs checked — show the list

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

Showing the 60 most looked-up of 1,741 medications checked with no known interaction — see the full Hibiscus Sabdariffa list.

See the full Hibiscus Sabdariffa 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
Hibiscus Sabdariffa 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 Tamoxifen Citrate NDC codes and packages › Every package, labeler and price in the FDA directory 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 Hibiscus Sabdariffa and Tamoxifen Citrate Together: Common Questions

Can you take Hibiscus Sabdariffa with Tamoxifen Citrate?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Hibiscus Sabdariffa and Tamoxifen Citrate?
Tamoxifen Citrate belongs to more than one drug category, and Hibiscus Sabdariffa 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 Hibiscus Sabdariffa and Tamoxifen Citrate interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Tamoxifen Citrate and Hibiscus Sabdariffa?

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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.