Drug & supplement interaction

Alfalfa + Letrozole

Letrozole brand name: Femara.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Alfalfa 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

Alfalfa 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 Alfalfa 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.

Alfalfa safety at a glance

Alfalfa overall Use caution Generally considered food-safe in small amounts, but supplements and raw sprouts carry real risks for some people.

Pregnancy Possibly Unsafe When used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity. Read the full pregnancy detail

Breastfeeding Possibly Unsafe When used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity. Read the full breastfeeding detail

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 Alfalfa? 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. Alfalfa has documented interactions with 6 drug classes — the most serious being warfarin (coumadin) (major), antidiabetes drugs (moderate) and contraceptive 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

Alfalfa Does Interact With Other Medications

Alfalfa has 2 major, 581 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.

Major 2 Moderate 581 No known interaction 2,247 (incl. Letrozole)

Taking anything else?

Check Another of Your Medications Against Alfalfa

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

What to actually watch for

No Interaction Found — But Data Suggests Alfalfa 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.

Joint pain Additional detail
Alfalfa
“Alfalfa products, including sprouts, seeds, and tablets, have been found to be contaminated with Escherichia coli, Salmonella, and Listeria monocytogenes, which have caused documented infections.

Orally, alfalfa has been associated with the development of a lupus-like syndrome in animals and humans, as well as with possible exacerbations of lupus in patients with known systemic lupus erythematosus (SLE).”

Alfalfa · Natural Medicines adverse-effect record, reported in systemic lupus erythematosus (sle).
6 sources cited

5600. Farber JM, Carter AO, Varughese PV, et al. Listeriosis traced to the consumption of alfalfa tablets and soft cheese [Letter to the Editor]. N Engl J Med 1990;322:338. PubMed

30566. Mohle-Boetani J, Werner B, Polumbo M, and et al. From the Centers for Disease Control and Prevention. Alfalfa sprouts-- Arizona, California, Colorado, and New Mexico, February-April, 2001. JAMA 2-6-2002;287(5):581-582.

30568. Howard, M. B. and Hutcheson, S. W. Growth dynamics of Salmonella enterica strains on alfalfa sprouts and in waste seed irrigation water. Appl.Environ.Microbiol. 2003;69(1):548-553.

30572. Strapp, C. M., Shearer, A. E., and Joerger, R. D. Survey of retail alfalfa sprouts and mushrooms for the presence of Escherichia coil O157:H7, Salmonella, and Listeria with BAX, and evaluation of this polymerase chain reaction-based system with experimen

30569. Winthrop, K. L., Palumbo, M. S., Farrar, J. A., Mohle-Boetani, J. C., Abbott, S., Beatty, M. E., Inami, G., and Werner, S. B. Alfalfa sprouts and Salmonella Kottbus infection: a multistate outbreak following inadequate seed disinfection with heat and chl

30564. Backer, H. D., Mohle-Boetani, J. C., Werner, S. B., Abbott, S. L., Farrar, J., and Vugia, D. J. High incidence of extra-intestinal infections in a Salmonella Havana outbreak associated with alfalfa sprouts. Public Health Rep. 2000;115(4):339-345. PubMed
Letrozole

Listed in the ADVERSE REACTIONS section of the FDA label for Letrozole. Read the label on DailyMed ›
Swelling Additional detail
Alfalfa
“Dermatitis associated with alfalfa use has been reported. In a 1954 publication, dermatitis was noted in a 61-year-old female consuming 4-6 cups of tea made with two tablespoonfuls of alfalfa seeds for approximately two months prior to onset. Examination revealed diffuse, confluent edema and erythema on the face, eyelids, ears, hands, forearms, and distal humeral regions. The dermatitis improved with treatment;”

Alfalfa · Natural Medicines adverse-effect record, reported in dermatitis.
1 source cited

30609. Kaufman W. Alfalfa seed dermatitis. JAMA 1954;155(12):1058-1059. PubMed
Letrozole

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

Reported for Alfalfa but not commonly for Letrozole: stomach upset, bloating or gas, diarrhea and low potassium.

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

Alfalfa in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity.

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

We hold 3,559 real supplement products containing Alfalfa, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Alfalfa. Even though Alfalfa 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 Alfalfa 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 Alfalfa

Top 10%

#82 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 Alfalfa reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Alfalfa and Letrozole records this page draws on were last updated July 10, 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Alfalfa

What is Alfalfa?

High cholesterol
Digestive complaints
Menopausal symptoms
Arthritis and joint pain
General nutritional supplement

Alfalfa is a nutrient-rich legume that people use for high cholesterol, menopause symptoms, and general wellness, but solid human evidence for most of these uses is limited. It is best avoided by people with autoimmune diseases, those who are pregnant or breastfeeding, and anyone with a weakened immune system, and you should check with your pharmacist or doctor before trying it.

Medicago sativa · Fabaceae · Leaves, sprouts, and seeds · Capsules, tablets, dried leaf tea, sprouts, liquid extract, and powder

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

Alfalfa: dosing

There is no well-established standard dose for alfalfa supplements. Products vary widely in strength and form, including capsules, tablets, teas, and extracts.Because a proven safe and effective dose has not been set, the best approach is to follow the directions on the product label and not exceed the recommended amount. They can help you decide if it is appropriate for you.

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

Read the full Alfalfa 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 & Alfalfa

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

2Major

581Moderate

0Minor

2,246No known interaction

2 Major 581 Moderate 2,246 No interaction

Major

2 interactions

Moderate

581 interactions

Showing 60 of 581 moderate interactions — see all 581 on the Alfalfa page.

No interaction 2,246 drugs checked — show the list

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

Showing the 60 most looked-up of 2,246 medications checked with no known interaction — see the full Alfalfa list.

See the full Alfalfa interactions page

See every supplement checked against Letrozole, ranked by severity

Evidence & sources

Alfalfa References

The 32 references that drive our Alfalfa 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.

Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
Kurzer MS, Xu X. Dietary phytoestrogens. Annu Rev Nutr 1997;17:353-81. PubMed
Farber JM, Carter AO, Varughese PV, et al. Listeriosis traced to the consumption of alfalfa tablets and soft cheese [Letter to the Editor]. N Engl J Med 1990;322:338. PubMed
Molgaard J, von Schenck H, Olsson AG. Alfalfa seeds lower low density lipoprotein cholesterol and apolipoprotein B concentrations in patients with type II hyperlipoproteinemia. Atherosclerosis 1987;65:173-9. PubMed
Light TD, Light JA. Acute renal transplant rejection possibly related to herbal medications. Am J Transplant 2003;3:1608-9. PubMed
Prete PE. The mechanism of action of L-canavanine in inducing autoimmune phenomena. Arthritis Rheum 1985;28:1198-200. PubMed
Alcocer-Varela J, Iglesias A, Llorente L, Alarcon-Segovia D. Effects of L-canavanine on T cells may explain the induction of systemic lupus erythematosus by alfalfa. Arthritis Rheum 1985;28:52-7. PubMed
Roberts JL, Hayashi JA. Exacerbation of SLE associated with alfalfa ingestion. N Engl J Med 1983;308:1361. DOI
Feingold, R. M. Should we fear "health foods"? Arch Intern Med 7-12-1999;159(13):1502. PubMed
Taormina, P. J., Beuchat, L. R., and Slutsker, L. Infections associated with eating seed sprouts: an international concern. Emerg.Infect.Dis 1999;5(5):626-634. PubMed
Backer, H. D., Mohle-Boetani, J. C., Werner, S. B., Abbott, S. L., Farrar, J., and Vugia, D. J. High incidence of extra-intestinal infections in a Salmonella Havana outbreak associated with alfalfa sprouts. Public Health Rep. 2000;115(4):339-345. PubMed
Mohle-Boetani J, Werner B, Polumbo M, and et al. From the Centers for Disease Control and Prevention. Alfalfa sprouts-- Arizona, California, Colorado, and New Mexico, February-April, 2001. JAMA 2-6-2002;287(5):581-582.
Howard, M. B. and Hutcheson, S. W. Growth dynamics of Salmonella enterica strains on alfalfa sprouts and in waste seed irrigation water. Appl.Environ.Microbiol. 2003;69(1):548-553.
Winthrop, K. L., Palumbo, M. S., Farrar, J. A., Mohle-Boetani, J. C., Abbott, S., Beatty, M. E., Inami, G., and Werner, S. B. Alfalfa sprouts and Salmonella Kottbus infection: a multistate outbreak following inadequate seed disinfection with heat and chl
Strapp, C. M., Shearer, A. E., and Joerger, R. D. Survey of retail alfalfa sprouts and mushrooms for the presence of Escherichia coil O157:H7, Salmonella, and Listeria with BAX, and evaluation of this polymerase chain reaction-based system with experimen
Akaogi, J., Barker, T., Kuroda, Y., Nacionales, D. C., Yamasaki, Y., Stevens, B. R., Reeves, W. H., and Satoh, M. Role of non-protein amino acid L-canavanine in autoimmunity. Autoimmun.Rev 2006;5(6):429-435. PubMed
Burden and causes of foodborne disease in Australia: Annual report of the OzFoodNet network, 2005. Commun.Dis Intell. 2006;30(3):278-300.
Shemesh, M., Lindner, H. R., and Ayalon, N. Affinity of rabbit uterine oestradiol receptor for phyto-oestrogens and its use in a competitive protein-binding radioassay for plasma coumestrol. J Reprod.Fertil. 1972;29(1):1-9. PubMed
Elakovich, S. D. and Hampton, J. M. Analysis of coumestrol, a phytoestrogen, in alfalfa tablets sold for human consumption. J Agric.Food Chem. 1984;32(1):173-175. PubMed
Malinow, M. R., Bardana, E. J., Jr., Pirofsky, B., Craig, S., and McLaughlin, P. Systemic lupus erythematosus-like syndrome in monkeys fed alfalfa sprouts: role of a nonprotein amino acid. Science 4-23-1982;216(4544):415-417. PubMed
Malinow, M. R., McLaughlin, P., and Stafford, C. Alfalfa seeds: effects on cholesterol metabolism. Experientia 5-15-1980;36(5):562-564. PubMed
Farnsworth, N. R. Alfalfa pills and autoimmune diseases. Am J Clin Nutr. 1995;62(5):1026-1028. DOI
Herbert, V. and Kasdan, T. S. Alfalfa, vitamin E, and autoimmune disorders. Am J Clin Nutr 1994;60(4):639-640.
Mahon, B. E., Ponka, A., Hall, W. N., Komatsu, K., Dietrich, S. E., Siitonen, A., Cage, G., Hayes, P. S., Lambert-Fair, M. A., Bean, N. H., Griffin, P. M., and Slutsker, L. An international outbreak of Salmonella infections caused by alfalfa sprouts grow
Gray, A. M. and Flatt, P. R. Pancreatic and extra-pancreatic effects of the traditional anti- diabetic plant, Medicago sativa (lucerne). Br J Nutr. 1997;78(2):325-334.
Van Beneden, C. A., Keene, W. E., Strang, R. A., Werker, D. H., King, A. S., Mahon, B., Hedberg, K., Bell, A., Kelly, M. T., Balan, V. K., Mac Kenzie, W. R., and Fleming, D. Multinational outbreak of Salmonella enterica serotype Newport infections due to
Rubenstein AH, Levin NW, and Elliott GA. Manganese-induced hypoglycemia. Lancet 1962;1348-1351.
Kaufman W. Alfalfa seed dermatitis. JAMA 1954;155(12):1058-1059. PubMed
Ponka A, Andersson Y, Siitonen A, and et al. Salmonella in alfalfa sprouts. Lancet 1995;345:462-463. PubMed
Puschner B, Chen X, Read D, Affolter VK. Alfalfa hay induced primary photosensitization in horses. Vet J. 2016 May;211:32-8. 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 Alfalfa and Letrozole Together: Common Questions

Is it safe to take Alfalfa with Letrozole?

We do not list a known interaction between Alfalfa 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 Alfalfa and Letrozole have any of the same side effects?

Yes — our sources link each of them separately to 2 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 Alfalfa and Letrozole combination checked?

Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Alfalfa has documented interactions with 6 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 Alfalfa interact with any other medications?

Yes. Alfalfa has 583 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 — Alfalfa 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

Alfalfa 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 32 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Alfalfa?

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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.