Drug & supplement interaction

Agaricus Mushroom + Letrozole

Letrozole brand name: Femara.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Agaricus Mushroom and Letrozole in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Agaricus Mushroom and Letrozole

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Letrozole and Agaricus Mushroom in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Agaricus Mushroom safety at a glance

Agaricus Mushroom overall Use caution Generally tolerated as a food, but supplement safety and long-term effects are not well established.
Pregnancy Avoid Not enough safety data, so it is best to avoid supplement doses during pregnancy.
Breastfeeding Avoid Not enough safety data, so avoid supplement doses while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Letrozole and Agaricus Mushroom? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Letrozole

Interactions in our licensed database are recorded against drug classes, not just single drug names. Letrozole is filed under 4 classifications — including aromatase inhibitors, cytochrome p450 2c19 (cyp2c19) inhibitors, cytochrome p450 3a4 (cyp3a4) substrates. Agaricus Mushroom has documented interactions with 1 drug class — the most serious being antidiabetes drugs (moderate) — and none of Letrozole’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Agaricus Mushroom Does Interact With Other Medications

Agaricus Mushroom has 86 moderate known drug interactions in our database — Letrozole isn’t one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Agaricus Mushroom

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

What to actually watch for

No Interaction Found — But Data Suggests Agaricus Mushroom and Letrozole May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Nausea Additional detail

    Agaricus Mushroom

    “In one clinical trial, mild gastrointestinal side effects such as nausea, diarrhea, and abdominal discomfort were reported in 6 of 78 patients taking a specific agaricus powder product (Sen-Sei-Ro Powder Gold, Kyowa Wellness Co., Ltd.) 1.8-5.4 grams orally daily for 60 days.”

    Agaricus Mushroom · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 17185. Ohno S, Sumiyoshi Y, Hashine K, et al. Phase I clinical study of the dietary supplement, Agaricus blazei Murill, in cancer patients in remission. Evid Based Complement Alternat Med 2011, doi 10.1155/2011/192381.

    Letrozole

    Listed in the ADVERSE REACTIONS section of the FDA label for Letrozole. Read the label on DailyMed ›

Reported for Agaricus Mushroom but not commonly for Letrozole: stomach upset, an allergic reaction, liver problems and diarrhea.

Effects for Letrozole come from the ADVERSE REACTIONS section of its FDA label; effects for Agaricus Mushroom come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Letrozole Is Prescribed For, and What Agaricus Mushroom Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Letrozole is a prescription medicine with approved uses on its FDA label. Agaricus Mushroom is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Letrozole is prescribed for: 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.

Agaricus Mushroom has been studied for:

  • Cancer studied, not established Agaricus Mushroom has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Agaricus Mushroom for cancer

    Although there is interest in using oral agaricus mushroom for the treatment of various types of cancer, there is insufficient reliable information about the clinical effects of agaricus mushroom for this purpose.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Letrozole on your own; if you are taking Agaricus Mushroom for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

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

We hold 671 real supplement products containing Agaricus Mushroom, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Agaricus Mushroom. Even though Agaricus Mushroom itself has no known interaction with Letrozole, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Agaricus Mushroom 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 Agaricus Mushroom
Top 25%

#298 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Agaricus Mushroom reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Agaricus Mushroom and Letrozole records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Agaricus Mushroom

What is Agaricus Mushroom?

  • Immune support
  • General wellness and antioxidant
  • Adjunct interest during cancer care
  • Blood sugar support
  • Cholesterol and heart health

Agaricus mushroom (often Agaricus blazei/subrufescens) is a culinary and medicinal mushroom studied mostly for possible immune and antioxidant effects. The human evidence is limited and not strong enough to recommend it for treating any disease. If you want to try it, talk with your pharmacist or doctor first, especially if you have a health condition or take other medicines.

Agaricus subrufescens · Agaricaceae · Fruiting body (mushroom), sometimes mycelium · Capsules, tablets, powders, dried mushroom, liquid extracts, teas

An interaction check asks whether these two react with each other — it does not ask whether Agaricus Mushroom is a good idea for someone in your situation. Here is what our Agaricus Mushroom record says about it on its own.

Agaricus Mushroom: dosing

There is no established standard dose for Agaricus mushroom supplements. Studies have used different products and amounts, so it is hard to recommend one specific dose.If you choose to use it, follow the directions on the product label and do not exceed the recommended amount. Choosing products from reputable companies that test for purity is wise, since supplements are not tightly regulated.

From our Agaricus Mushroom monograph — the full record covers uses, side effects and every documented interaction.

Read the full Agaricus Mushroom 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 & Agaricus Mushroom

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Agaricus Mushroom page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Agaricus Mushroom list.

See the full Agaricus Mushroom interactions page
See every supplement checked against Letrozole, ranked by severity
Evidence & sources

Agaricus Mushroom References

The 5 references that drive our Agaricus Mushroom monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Hsu CH, Liao YL, Lin SC, et al. The mushroom Agaricus Blazei Murill in combination with metformin and gliclazide improves insulin resistance in type 2 diabetes: a randomized, double-blinded, and placebo-controlled clinical trial. J Altern Complement Med 2
  2. Mukai H, Watanabe T, Ando M, Katsumata N. An alternative medicine, Agaricus blazei, may have induced severe hepatic dysfunction in cancer patients. Jpn J Clin Oncol 2006;36:808-10. PubMed
  3. Ohno S, Sumiyoshi Y, Hashine K, et al. Phase I clinical study of the dietary supplement, Agaricus blazei Murill, in cancer patients in remission. Evid Based Complement Alternat Med 2011, doi 10.1155/2011/192381.
  4. Suehiro M, Katoh N, Kishimoto S. Chelitis due to Agaricus blazei Murill mushroom extract. Contact Dermatitis 2007;56(5):293-4.
  5. Iwai N, Okuda T, Sawada R, et al. Interstitial lung disease associated with Agaricus blazei Murill in a patient with pancreatic ductal adenocarcinoma receiving gemcitabine-based therapy. Case Rep Gastroenterol 2022;16(1):229-234.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Agaricus Mushroom and Letrozole Together: Common Questions

Is it safe to take Agaricus Mushroom with Letrozole?
We do not list a known interaction between Agaricus Mushroom and Letrozole. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Agaricus Mushroom and Letrozole have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Agaricus Mushroom and Letrozole used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Agaricus Mushroom in each. That is a conversation for your prescriber, especially if Letrozole is being adjusted to a target.
How was the Agaricus Mushroom and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Agaricus Mushroom has documented interactions with 1 drug class — none of Letrozole's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Agaricus Mushroom interact with any other medications?
Yes. Agaricus Mushroom has 86 documented drug interactions in our database — Letrozole is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Letrozole interact with any supplements?
Yes. Letrozole has documented interactions with 142 supplements in our database — Agaricus Mushroom is not one of them. The Letrozole interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Agaricus Mushroom monograph Uses, safety profile, and every drug interaction in one place Letrozole drug information The full plain-English guide to this medication Letrozole supplement interactions Every supplement checked against Letrozole, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Agaricus Mushroom?

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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.