Drug & supplement interaction

Mace + 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 Mace 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

Mace 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 Mace 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.

Mace safety at a glance

Mace overall Use caution Safe as a culinary spice but large or concentrated doses can be toxic.
Pregnancy Possibly Unsafe When used orally in medicinal amounts. Mace might have abortifacient activity, and its safrole content might be mutagenic. Read the full pregnancy detail
Breastfeeding Use caution Food amounts are probably fine, but avoid concentrated supplements due to lack of safety data.

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Letrozole and Mace? 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. Mace has documented interactions with 4 drug classes — the most serious being cns depressants (moderate), cytochrome p450 1a2 (cyp1a2) substrates (moderate) and immunosuppressants (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

Mace Does Interact With Other Medications

Mace has 500 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 500 No known interaction 2,330 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Mace

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

What to actually watch for

No Interaction Found — But Data Suggests Mace and Letrozole May Share Several of the Same Side Effects

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.

  • Flushing Additional detail

    Mace

    “There are no reports of adverse cardiovascular events due to ingestion of mace. However, mace contains myristicin, which is structurally similar to certain hallucinogenic chemicals. High intake of nutmeg, a related herb, has been associated with non-specific electrocardiographic changes, tachycardia, palpitations, weak pulse, hypotension, chest pain, and flushing (12,19293,19300,25547,25943).”

    Mace · Natural Medicines adverse-effect record, reported in hypotension.

    5 sources cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    2. 19293. McKenna A, Nordt SP, Ryan J. Acute nutmeg poisoning. Eur J Emerg Med 2004;11:240-1. PubMed
    3. 19300. Stein U, Greyer H, Hentschel H. Nutmeg (myristicin) poisoning-report on a fatal case and a series of cases recorded by a poison information centre. Forensic Sci Int 2001;118:87-90. PubMed
    4. 25547. Grover JK, Khandkar S, Vats V, Dhunnoo Y, Das D. Pharmacological studies on Myristica fragrans--antidiarrheal, hypnotic, analgesic and hemodynamic (blood pressure) parameters. Methods Find Exp Clin Pharmacol. 2002;24(10):675-80. PubMed
    5. 25943. Barceloux DG. Nutmeg (Myristica fragrans Houtt.). Dis Mon. 2009;55(6):373-9. PubMed

    Letrozole

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

  • Dizziness / Headache Additional detail

    Mace

    “There are no reports of adverse neurologic or central nervous system (CNS)-related events due to ingestion of mace. However, mace contains myristicin, which is structurally similar to certain hallucinogenic chemicals. High intake of nutmeg, a similar herb, has been reported to cause headache, dizziness, drowsiness, hot and cold sensations, sensations of limb loss, convulsions, and coma.”

    Mace · Natural Medicines adverse-effect record, reported in cluster headache.

    4 sources cited
    1. 2563. Sangalli BC, Chiang W. Toxicology of nutmeg abuse. Clin Toxicol 2000;38:671-8. PubMed
    2. 19294. Panayotopoulos DJ, Chisholm DD. Hallucinogenic effect of nutmeg. Br Med J 1970;1:754. PubMed
    3. 19300. Stein U, Greyer H, Hentschel H. Nutmeg (myristicin) poisoning-report on a fatal case and a series of cases recorded by a poison information centre. Forensic Sci Int 2001;118:87-90. PubMed
    4. 19487. Venables GS, Evered D, Hall R. Letter: Nutmeg poisoning. Br Med J 1976;1:96. PubMed

    Letrozole

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

  • Nausea Additional detail

    Mace

    “There are no reports of adverse gastrointestinal events due to ingestion of mace. However, mace contains myristicin, which is structurally similar to certain hallucinogenic chemicals. High intake of nutmeg, a similar spice, has been reported to cause nausea and vomiting, epigastric pain, and gastroenteritis. Theoretically, high intake of mace may have similar effects.”

    Mace · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    3 sources cited
    1. 2563. Sangalli BC, Chiang W. Toxicology of nutmeg abuse. Clin Toxicol 2000;38:671-8. PubMed
    2. 19294. Panayotopoulos DJ, Chisholm DD. Hallucinogenic effect of nutmeg. Br Med J 1970;1:754. PubMed
    3. 19300. Stein U, Greyer H, Hentschel H. Nutmeg (myristicin) poisoning-report on a fatal case and a series of cases recorded by a poison information centre. Forensic Sci Int 2001;118:87-90. PubMed

    Letrozole

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

Reported for Mace but not commonly for Letrozole: hallucinations, confusion, anxiety or restlessness and a fast or pounding heartbeat.

Effects for Letrozole come from the ADVERSE REACTIONS section of its FDA label; effects for Mace 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.

Special populations

Mace in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used orally in medicinal amounts. Mace might have abortifacient activity, and its safrole content might be mutagenic.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

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

We hold 38 real supplement products containing Mace, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Mace. Even though Mace 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 Mace 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 Mace
Top half

#466 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 Mace reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Mace 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 Mace

What is Mace?

  • Digestive upset and gas
  • Flavoring and culinary spice
  • Nausea
  • Appetite stimulation
  • Traditional pain or muscle relief

Mace is the lacy red covering of the nutmeg seed and comes from the same tree as nutmeg. It is mostly used as a cooking spice and in traditional medicine for digestion, but there is little solid human research to support its health uses. In normal food amounts it is generally safe, but large doses can be toxic, so use it as a spice and check with your pharmacist before taking concentrated supplements.

Myristica fragrans · Myristicaceae · The dried red, lacy covering (aril) of the nutmeg seed · Whole dried blades, ground powder, essential oil, capsules

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

Mace: dosing

There is no established standardized medicinal dose for mace. As a spice, the amount used in cooking is small and considered safe.If you choose to use a mace supplement, follow the directions on the product label and do not exceed them. Because high amounts can be toxic, more is not better.

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

Read the full Mace 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 & Mace

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

0Major
500Moderate
0Minor
2,329No known interaction
500 Moderate 2,329 No interaction
Moderate

500 interactions

Showing 60 of 500 moderate interactions — see all 500 on the Mace page.

No interaction 2,329 drugs checked — show the list

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

Showing the 60 most looked-up of 2,329 medications checked with no known interaction — see the full Mace list.

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

Mace References

The 18 references that drive our Mace 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. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Sangalli BC, Chiang W. Toxicology of nutmeg abuse. Clin Toxicol 2000;38:671-8. PubMed
  3. Hallstrom H, Thuvander A. Toxicological evaluation of myristicin. Nat Toxins 1997;5:186-92. DOI
  4. Jeong HG, Yun CH. Induction of rat hepatic cytochrome P450 enzymes by myristicin. Biochem Biophys Res Commun 1995;217:966-71. PubMed
  5. McKenna A, Nordt SP, Ryan J. Acute nutmeg poisoning. Eur J Emerg Med 2004;11:240-1. PubMed
  6. Panayotopoulos DJ, Chisholm DD. Hallucinogenic effect of nutmeg. Br Med J 1970;1:754. PubMed
  7. Stein U, Greyer H, Hentschel H. Nutmeg (myristicin) poisoning-report on a fatal case and a series of cases recorded by a poison information centre. Forensic Sci Int 2001;118:87-90. PubMed
  8. Venables GS, Evered D, Hall R. Letter: Nutmeg poisoning. Br Med J 1976;1:96. PubMed
  9. Carstairs SD, Cantrell FL. The spice of life: an analysis of nutmeg exposures in California. Clin Toxicol (Phila) 2011;49:177-80. PubMed
  10. Abernethy MK, Becker LB. Acute nutmeg intoxication. Am J Emerg Med 1992;10:429-30. PubMed
  11. Checker R, Chatterjee S, Sharma D, et al. Immunomodulatory and radioprotective effects of lignans derived from fresh nutmeg mace (Myristica fragrans) in mammalian splenocytes. Int Immunopharmacol. 2008;8(5):661-669. PubMed
  12. Sell AB, Carlini EA. Anesthetic action of methyleugenol and other eugenol derivatives. Pharmacology. 1976;14(4):367-77. PubMed
  13. Fundarò A, Cassone MC. [Action of essential oils of chamomile, cinnamon, absinthium, mace and origanum on operant conditioning behavior of the rat]. Boll Soc Ital Biol Sper. 1980;56(22):2375-80.
  14. Grover JK, Khandkar S, Vats V, Dhunnoo Y, Das D. Pharmacological studies on Myristica fragrans--antidiarrheal, hypnotic, analgesic and hemodynamic (blood pressure) parameters. Methods Find Exp Clin Pharmacol. 2002;24(10):675-80. PubMed
  15. Barceloux DG. Nutmeg (Myristica fragrans Houtt.). Dis Mon. 2009;55(6):373-9. PubMed

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 Mace and Letrozole Together: Common Questions

Is it safe to take Mace with Letrozole?
We do not list a known interaction between Mace 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 Mace and Letrozole have any of the same side effects?
Yes — our sources link each of them separately to 4 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.
How was the Mace and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Mace has documented interactions with 4 drug classes — 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 Mace interact with any other medications?
Yes. Mace has 500 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 — Mace 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

Mace 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 18 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Mace?

Our pharmacists answer your medication & supplement questions — free.

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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.