Drug & supplement interaction

Marjoram + 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 Marjoram 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.

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Interaction report

Marjoram 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 Marjoram 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.

Marjoram safety at a glance

Marjoram overall Use caution Generally safe as a food, but concentrated extracts and essential oils have limited human safety data.
Pregnancy Possibly Unsafe When used in medicinal amounts; marjoram has the potential for stimulating menstruation. Avoid amounts greater than those found in foods. Read the full pregnancy detail
Breastfeeding Use caution Food amounts are likely fine, but avoid medicinal doses since safety is not established.

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 Marjoram? 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. Marjoram has documented interactions with 3 drug classes — the most serious being anticholinergic drugs (moderate), anticoagulant/antiplatelet drugs (moderate) and cholinergic 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

Marjoram Does Interact With Other Medications

Marjoram has 338 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 338 No known interaction 2,492 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Marjoram

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

What to actually watch for

What Marjoram Itself Has Been Linked To

This is not an interaction — nothing below involves Letrozole. It is the side-effect record for Marjoram on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Marjoram, this list is the first place to look.

  • A skin rash Additional detail

    “Possible allergic contact dermatitis in children with pre-existing childhood atopic eczema was observed in a randomized clinical trial employing extended use of essential oils, including sweet marjoram essential oil. A case report describes a 38-year old woman who had an exacerbation of perioral dermatitis after eating food seasoned with marjoram.”

    Marjoram · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 58049. Anderson C, Lis-Balchin M, Kirk-Smith M. Evaluation of massage with essential oils on childhood atopic eczema. Phytother Res 2000;14(6):452-6. PubMed
    2. 33865. Farkas, J. Perioral dermatitis from marjoram, bay leaf and cinnamon. Contact Dermatitis 1981;7(2):121. PubMed

Everything above comes from the Natural Medicines adverse-effect record for Marjoram — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Letrozole’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Letrozole column appears here.

Special populations

Marjoram in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used in medicinal amounts; marjoram has the potential for stimulating menstruation. Avoid amounts greater than those found in foods.

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

We hold 7 real supplement products containing Marjoram, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Marjoram. Even though Marjoram 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 Marjoram 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 Marjoram
Top half

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

What is Marjoram?

Marjoram
  • Digestive upset
  • Sleep and relaxation
  • Respiratory complaints (cough, congestion)
  • Menstrual discomfort
  • Aromatherapy for stress

Marjoram is a Mediterranean kitchen herb related to oregano that is widely used in food and traditional medicine for digestive, sleep, and respiratory complaints. Most of its health claims rest on traditional use and small lab or animal studies rather than strong human trials. It is generally considered safe as a food, but concentrated supplements and essential oils should be used with caution and avoided in pregnancy.

Origanum majorana · Lamiaceae · Leaves, flowering tops, and essential oil · Culinary herb, tea, capsules, tincture, essential oil (for aromatherapy)

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

Marjoram: dosing

There is no official, well-established medicinal dose for marjoram. The amounts used in research and traditional practice vary widely depending on the form.If you use a marjoram product, follow the directions on the label and do not exceed the recommended amount.

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

Read the full Marjoram 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 & Marjoram

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

0Major
338Moderate
0Minor
2,491No known interaction
338 Moderate 2,491 No interaction
Moderate

338 interactions

Showing 60 of 338 moderate interactions — see all 338 on the Marjoram page.

No interaction 2,491 drugs checked — show the list

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

Showing the 60 most looked-up of 2,491 medications checked with no known interaction — see the full Marjoram list.

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

Marjoram References

The 11 references that drive our Marjoram 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. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  2. Orhan, I., Kartal, M., Kan, Y., and Sener, B. Activity of essential oils and individual components against acetyl- and butyrylcholinesterase. Z.Naturforsch.C. 2008;63(7-8):547-553.
  3. Farkas, J. Perioral dermatitis from marjoram, bay leaf and cinnamon. Contact Dermatitis 1981;7(2):121. PubMed
  4. Anderson C, Lis-Balchin M, Kirk-Smith M. Evaluation of massage with essential oils on childhood atopic eczema. Phytother Res 2000;14(6):452-6. PubMed
  5. Ou, M. C., Hsu, T. F., Lai, A. C., Lin, Y. T., and Lin, C. C. Pain relief assessment by aromatic essential oil massage on outpatients with primary dysmenorrhea: a randomized, double-blind clinical trial. J Obstet.Gynaecol.Res 2012;38(5):817-822. PubMed
  6. Chung, Y. K., Heo, H. J., Kim, E. K., Kim, H. K., Huh, T. L., Lim, Y., Kim, S. K., and Shin, D. H. Inhibitory effect of ursolic acid purified from Origanum majorana L on the acetylcholinesterase. Mol.Cells 4-30-2001;11(2):137-143. DOI
  7. Yazdanparast, R. and Shahriyary, L. Comparative effects of Artemisia dracunculus, Satureja hortensis and Origanum majorana on inhibition of blood platelet adhesion, aggregation and secretion. Vascul.Pharmacol 2008;48(1):32-37. PubMed
  8. Mohamed MS, Saad HH, and Abd El Khalek MG. Daily consumption of marjoram oil improve the health status of patients with asthma. Pakistan Journal of Nutrition. 2008;7(2):312-316. DOI
  9. Bina F, Rahimi R. Sweet marjoram: a review of ethnopharmacology, phytochemistry, and biological activities. J Evid Based Complementary Altern Med 2017;22(1):175-85.
  10. Haj-Husein I, Tukan S, Alkazaleh F. The effect of marjoram (Origanum majorana) tea on the hormonal profile of women with polycystic ovary syndrome: a randomized controlled pilot study. J Hum Nutr Diet 2016;29(1):105-11.
  11. Chahra C, Anis H, Bissene D, et al. The effect of Origanum majorana tea on motor and non-motor symptoms in patients with idiopathic Parkinson's disease: A randomized controlled pilot study. Parkinsonism Relat Disord. 2021 Oct;91:23-7. 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 Marjoram and Letrozole Together: Common Questions

Is it safe to take Marjoram with Letrozole?
We do not list a known interaction between Marjoram 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.
How was the Marjoram and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Marjoram has documented interactions with 3 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 Marjoram interact with any other medications?
Yes. Marjoram has 338 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 — Marjoram 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

Marjoram 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 11 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Marjoram?

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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.