Drug & supplement interaction

Padang Cassia + Tamoxifen Citrate

Tamoxifen Citrate brand names: Nolvadex, Soltamox.

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

Tamoxifen Citrate falls into 2 drug categories that Padang Cassia can interact with; the most serious is rated moderate. There is some concern that ingesting large amounts of Padang cassia might cause hepatotoxicity in some people.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Padang Cassia and Tamoxifen Citrate

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Padang Cassia interacts with whole categories of medication. Tamoxifen Citrate falls into 2 of those categories, so it can interact with Padang Cassia in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

HEPATOTOXIC DRUGS

1 of 2

Why this applies to Tamoxifen Citrate

Tamoxifen Citrate falls under HEPATOTOXIC DRUGS — the group Padang Cassia interacts with.

There is some concern that ingesting large amounts of Padang cassia might cause hepatotoxicity in some people. Padang cassia contains coumarin. Coumarin has caused hepatotoxicity in animal models. In otherwise healthy humans, very high doses of coumarin, from 50-7000 mg daily, can result in hepatotoxicity that resolves when coumarin use is discontinued. Lower amounts might also cause liver problems in sensitive people, such as those with liver disease or those taking potentially hepatotoxic agents.
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 with pairing concentrated Padang cassia (a cassia cinnamon) with tamoxifen. Cassia cinnamon naturally contains coumarin, a compound that can stress the liver when taken in large supplement-sized amounts. Tamoxifen, on its own, can occasionally raise liver enzymes or cause liver inflammation, so stacking another potential liver stressor on top of it could, in theory, add to that risk.

To be honest, this is a theoretical worry based on how these substances behave, not on strong human studies with tamoxifen specifically. The cinnamon you sprinkle on food or in your coffee is very unlikely to matter. The caution is really about concentrated cinnamon capsules taken daily. If you're considering one, please check with your pharmacist or oncologist first, especially since your liver is already worth watching while on tamoxifen.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Press release. Cinnamon capsules to reduce blood sugar are medicinal products! Efficacy has not been scientifically proven - some products contain high levels of coumarin. Federal Institute of Risk Assessment (BfM), Germany, November 11, 2006. Available a
  2. Felter SP, Vassallo JD, Carlton BD, Daston GP. A safety assessment of coumarin taking into account species-specificity of toxicokinetics. Food Chem Toxicol 2006;44:462-75. PubMed
  3. Choi, J., Lee, K. T., Ka, H., Jung, W. T., Jung, H. J., and Park, H. J. Constituents of the essential oil of the Cinnamomum cassia stem bark and the biological properties. Arch Pharm Res 2001;24(5):418-423.
  4. Wang R, Wang R, Yan B. Extraction of essential oils from five cinnamon leaves and identification of their volatile compound compositions. Innovative Food Science and Emerging Technologies 2009;10:289-92. DOI
  5. Wang YH, Avula B, Nanayakkara NP, et al. Cassia cinnamon as a source of coumarin in cinnamon-flavored food and food supplements in the United States. J Agric Food Chem 2013;61(18):4470-6. PubMed
  6. Woehrlin F, Fry H, Abraham K, Preiss-Weigert A. Quantification of flavoring constituents in cinnamon: high variation of coumarin in cassia bark from the German retail market and in authentic samples from Indonesia. J Agric Food Chem 2010;58(19):10568-75. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

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

In vitro research shows that a methanol extract of Padang cassia inhibits cytochrome P450 3A4 (CYP3A4) activity. Theoretically, taking Padang cassia with CYP3A4 substrates might increase the effects and side effects of these substrates.
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 enzymes like CYP2D6, with CYP3A4 also playing a role) before it does its cancer-fighting work. The lab note we have says a concentrated extract of Padang cassia may slow down CYP3A4. In theory, slowing that enzyme could shift how tamoxifen is processed, which matters because you want steady, reliable levels for it to do its job.

Now the reassuring part: this is based only on test-tube research, not on real people, so it's quite theoretical. Cinnamon as a normal kitchen spice is very unlikely to cause trouble. The bigger question is concentrated cinnamon supplements, so please check with your oncologist or pharmacist before adding one.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Subehan S, Kadota S, Tezuka Y. In vitro mechanism-based inactivation of cytochrome P450 3A4 by a new constituent of Cinnamomum burmani. Planta Med 2008;74(12):1474-80.

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

Padang Cassia Also Interacts With Other Medications

Padang Cassia has 936 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 936 No known interaction 1,894 (incl. Tamoxifen Citrate)
Taking anything else?

Check Another of Your Medications Against Padang Cassia

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

From our Q&A

Questions About Padang Cassia 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 Padang Cassia 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 Padang Cassia 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 Padang Cassia 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 Padang Cassia
Top half

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

29 days ago today
Medication Tamoxifen Citrate
Top 5%

#137 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 Padang Cassia

What is Padang Cassia?

  • Adding flavor to food
  • Digestive upset
  • Blood sugar support
  • Antimicrobial purposes
  • Antioxidant support

Padang Cassia is a type of cinnamon (Indonesian or Korintje cinnamon) grown mainly in Indonesia and used widely as a kitchen spice. As a supplement, evidence for health benefits like blood sugar control is limited and mixed, and like other cassia cinnamons it naturally contains coumarin, which can be harmful to the liver in large amounts. Use food amounts freely, but talk to a pharmacist or doctor before taking concentrated cinnamon supplements.

Read the full Padang Cassia 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 & Padang Cassia

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

0Major
936Moderate
0Minor
1,893No known interaction
936 Moderate 1,893 No interaction
Moderate

936 interactions

Showing 60 of 936 moderate interactions — see all 936 on the Padang Cassia page.

No interaction 1,893 drugs checked — show the list

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

Showing the 60 most looked-up of 1,893 medications checked with no known interaction — see the full Padang Cassia list.

See the full Padang Cassia 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
Padang Cassia 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 Padang Cassia and Tamoxifen Citrate Together: Common Questions

Can you take Padang Cassia 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 2 interactions listed for Padang Cassia and Tamoxifen Citrate?
Tamoxifen Citrate belongs to more than one drug category, and Padang Cassia 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 Padang Cassia 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 Padang Cassia?

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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.