Drug & supplement interaction

Atractylodes + Letrozole

Letrozole brand name: Femara.

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

Letrozole falls into 2 drug categories that Atractylodes can interact with; the most serious is rated moderate. Theoretically, atractylodes may have an additive effect when used with other aromatase inhibitors.

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

Atractylodes and Letrozole

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

Why Are There 2 Interactions?

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

Moderate

AROMATASE INHIBITORS

1 of 2

Why this applies to Letrozole

Letrozole falls under AROMATASE INHIBITORS — the group Atractylodes interacts with.

Theoretically, atractylodes may have an additive effect when used with other aromatase inhibitors.
Laboratory research suggests that atractylodes and its constituents exhibit aromatase inhibitor effects.
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 simple version. Letrozole works by blocking an enzyme called aromatase, which lowers your estrogen levels to help fight breast cancer. In lab and animal studies, some compounds in atractylodes appear to do a little of that same job. So the concern is that the two could push in the same direction and add up, not that one cancels the other.

I want to be honest about the evidence here: this is only test-tube and animal research, so we don't really know if it matters in people taking Femara. In theory, extra aromatase blocking might mean more of the usual letrozole effects, like hot flashes, joint and bone aches, fatigue, or bone thinning over time. Since this is a cancer medicine where dosing matters, please don't add atractylodes without first running it by your oncologist or pharmacist.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Jiang H, Shi J, Li Y. Screening for compounds with aromatase inhibiting activities from Atractylodes macrocephala Koidz. Molecules. 2011 Apr 14;16(4):3146-51. PubMed
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

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

Theoretically, atractylodes might increase the levels of CYP3A4 substrates.
In animals, atractylodes administered at high doses has been shown to inhibit CYP3A1 activity, which is a homolog to the human CYP3A4 enzyme. This effect has not been shown 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 for letrozole (Femara). Your body clears letrozole largely through a liver enzyme called CYP3A4. In animal studies using high doses, atractylodes appeared to slow down a similar enzyme. If that same slowing happened in people, letrozole could build up a bit, which in theory might mean more of its usual effects like hot flashes, joint or muscle aches, tiredness, or headaches.

I want to be honest about how shaky this is. The signal comes only from lab and animal work at high doses, and it has not been shown in humans. So this is theoretical, and likely minor. Since letrozole treats breast cancer, I wouldn't add atractylodes without checking with your oncologist or pharmacist first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Muhamad N, Plengsuriyakarn T, Na-Bangchang K. Atractylodes lancea for cholangiocarcinoma: Modulatory effects on CYP1A2 and CYP3A1 and pharmacokinetics in rats and biodistribution in mice. PLoS One 2022;17(11):e0277614. 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

Atractylodes Also Interacts With Other Medications

Atractylodes has 126 moderate, 674 minor known drug interactions in our database — the Letrozole one above is among them. If you take anything else, check it against the full list below.

Moderate 126 Minor 674 No known interaction 2,030 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Atractylodes

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

From our Q&A

Questions About Atractylodes or Letrozole

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

This page covers Atractylodes only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Letrozole page lists 142 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), 7-methoxyflavone (moderate) and Acacia Rigidula (moderate).

By severity: 3 major · 99 moderate · 40 minor.

From our pharmacist’s overview on the Letrozole page

“Letrozole (Femara) is prescribed to keep hormone-driven breast cancer from returning, so a supplement that shifts its blood level can quietly undercut treatment. Give this list of 142 ingredients genuine respect, and learn the three major entries first.”

Reviewed by 2 · Jul 18, 2026

Open the Letrozole interaction page

One more smart check

Taking Atractylodes as Part of a Dietary Supplement Product? Check It for Interactions

We hold 691 real supplement products containing Atractylodes, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Atractylodes. Your product may carry other ingredients that interact with Letrozole too, on top of Atractylodes — 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 Atractylodes and Letrozole 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 Atractylodes
Top 25%

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

29 days ago today
Medication Letrozole
Top 5%

#50 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 Atractylodes

What is Atractylodes?

Atractylodes
  • Digestive upset and poor appetite
  • Bloating and fluid retention
  • General fatigue or 'weakness'
  • Diarrhea
  • Support within traditional formulas

Atractylodes is a root used for centuries in traditional Chinese, Japanese, and Thai medicine, mostly for digestive complaints and fatigue, often as part of multi-herb formulas. Modern research is still early and mostly from lab and animal studies, so its true benefits in people are not well proven. If you want to try it, talk with a pharmacist or doctor first, and avoid it during pregnancy and breastfeeding.

Read the full Atractylodes monograph & all interactions
Medication

About Letrozole

What Is Letrozole Used For?

Brand name: Femara

Letrozole (brand name Femara) is used to treat breast cancer in postmenopausal women whose tumors are driven by estrogen. It is used in three settings: as adjuvant (after-surgery) treatment for hormone receptor positive early breast cancer; as extended adjuvant treatment for women who have already completed about five years of tamoxifen therapy; and as first- or second-line treatment for locally advanced or metastatic (spread) breast cancer.

Femara is specifically indicated for first-line treatment of hormone receptor positive or receptor-unknown locally advanced or metastatic breast cancer, and for advanced breast cancer in women whose disease has progressed after antiestrogen therapy.

See full Letrozole drug information
Keep checking

Other Drugs & Atractylodes

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

0Major
126Moderate
674Minor
2,029No known interaction
126 Moderate 674 Minor 2,029 No interaction
Moderate

126 interactions

Showing 60 of 126 moderate interactions — see all 126 on the Atractylodes page.

Minor

674 interactions

Showing 60 of 674 minor interactions — see all 674 on the Atractylodes page.

No interaction 2,029 drugs checked — show the list

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

Showing the 60 most looked-up of 2,029 medications checked with no known interaction — see the full Atractylodes list.

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

Can you take Atractylodes with Letrozole?
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 Atractylodes and Letrozole?
Letrozole belongs to more than one drug category, and Atractylodes 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 Atractylodes and Letrozole 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 Letrozole and Atractylodes?

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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.