Drug & supplement interaction

Guarumo + 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 Guarumo 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

Guarumo 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 Guarumo 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.

Guarumo safety at a glance

Guarumo overall Use caution It has a long history of traditional use, but human safety data are very limited.
Pregnancy Avoid There is not enough safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid Safety while breastfeeding is unknown, so avoid use.

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

Still wondering about combining Letrozole and Guarumo? 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. Guarumo has documented interactions with 3 drug classes — the most serious being antidiabetes drugs (moderate), antihypertensive drugs (moderate) and cns depressants (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

Guarumo Does Interact With Other Medications

Guarumo has 505 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 505 No known interaction 2,325 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Guarumo

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

What to actually watch for

What Guarumo Itself Has Been Linked To

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

  • Heartburn Additional detail

    “Orally, guarumo seems to be well tolerated when used as a tea. Rare side effects reported in a clinical trial include excessive salivation, heartburn, and exhaustion. Topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.”

    Guarumo · Natural Medicines adverse-effect record, reported in dyspepsia.

    2 sources cited
    1. 26506. Revilla-Monsalve, M. C., Andrade-Cetto, A., Palomino-Garibay, M. A., Wiedenfeld, H., and Islas-Andrade, S. Hypoglycemic effect of Cecropia obtusifolia Bertol aqueous extracts on type 2 diabetic patients. J Ethnopharmacol 2007;111(3):636-40. PubMed
    2. 86369. Herrera-Arellano, A., Aguilar-Santamaria, L., Garcia-Hernandez, B., Nicasio-Torres, P., and Tortoriello, J. Clinical trial of Cecropia obtusifolia and Marrubium vulgare leaf extracts on blood glucose and serum lipids in type 2 diabetics. Phytomedicine 200 PubMed

    “Orally, excessive salivation and heartburn were reported by one patient each after drinking tea prepared from 1 gram of dried guarumo leaves three times daily before meals for 21 days.”

    Guarumo · Natural Medicines adverse-effect record, reported in dyspepsia.

    1 source cited
    1. 86369. Herrera-Arellano, A., Aguilar-Santamaria, L., Garcia-Hernandez, B., Nicasio-Torres, P., and Tortoriello, J. Clinical trial of Cecropia obtusifolia and Marrubium vulgare leaf extracts on blood glucose and serum lipids in type 2 diabetics. Phytomedicine 200 PubMed

Everything above comes from the Natural Medicines adverse-effect record for Guarumo — 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.

From our Q&A

Questions About Guarumo 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 Guarumo 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 Guarumo 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

How much people look this up

Where Guarumo 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 Guarumo
Top half

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

About Guarumo

What is Guarumo?

Guarumo
  • Type 2 diabetes / blood sugar support
  • High blood pressure
  • Cough, asthma, and bronchitis
  • Heart failure symptoms
  • Liver and rheumatic complaints

Guarumo (Cecropia obtusifolia) is a tropical tree used in Latin American traditional medicine, most often as a leaf tea for diabetes and high blood pressure. Some early laboratory and small human studies suggest it may modestly affect blood sugar, but the evidence is limited and not strong enough to recommend it as a treatment. Talk with your pharmacist or doctor before using it, especially if you have a chronic condition or take medication.

Cecropia obtusifolia · Urticaceae · Leaves (most common), bark, and root · Tea (infusion or decoction), liquid extracts, capsules, and dried leaf

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

Guarumo: dosing

There is no established standard dose for guarumo. Traditional use most often involves a tea made from the dried leaves, but the amount of active compounds can vary a lot between products and even between batches.If you choose to use a guarumo product, follow the directions on the label and do not exceed them.

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

Read the full Guarumo 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 & Guarumo

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

0Major
505Moderate
0Minor
2,324No known interaction
505 Moderate 2,324 No interaction
Moderate

505 interactions

Showing 60 of 505 moderate interactions — see all 505 on the Guarumo page.

No interaction 2,324 drugs checked — show the list

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

Showing the 60 most looked-up of 2,324 medications checked with no known interaction — see the full Guarumo list.

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

Guarumo References

The 6 references that drive our Guarumo 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. Revilla-Monsalve, M. C., Andrade-Cetto, A., Palomino-Garibay, M. A., Wiedenfeld, H., and Islas-Andrade, S. Hypoglycemic effect of Cecropia obtusifolia Bertol aqueous extracts on type 2 diabetic patients. J Ethnopharmacol 2007;111(3):636-40. PubMed
  2. Perez-Guerrero, C., Herrera, M. D., Ortiz, R., Alvarez, de Sotomayor, and Fernandez, M. A. A pharmacological study of Cecropia obtusifolia Bertol aqueous extract. J Ethnopharmacol 2001;76(3):279-84. PubMed
  3. Vidrio, H., Garcia-Marquez, F., Reyes, J., and Soto, R. M. Hypotensive activity of Cecropia obtusifolia. J Pharm Sci 1982;71:475-76. PubMed
  4. Salas, I., Brenes, J. R., and Morales, O. M. Antihypertensive effect of Cecropia obtusifolia (Moraceae) leaf extract on rats. Rev Biol Trop 1987;35(1):127-30.
  5. Salas, I. G., Morales, O. M., and Brenes, J. R. Effect of chronic administration of Cecropia obtusifolia (Moraceae) on mean arterial pressure in rats. Rev Biol Trop 1987;35(2):359-62.
  6. Herrera-Arellano, A., Aguilar-Santamaria, L., Garcia-Hernandez, B., Nicasio-Torres, P., and Tortoriello, J. Clinical trial of Cecropia obtusifolia and Marrubium vulgare leaf extracts on blood glucose and serum lipids in type 2 diabetics. Phytomedicine 200 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 Guarumo and Letrozole Together: Common Questions

Is it safe to take Guarumo with Letrozole?
We do not list a known interaction between Guarumo 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 Guarumo and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Guarumo 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 Guarumo interact with any other medications?
Yes. Guarumo has 505 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 — Guarumo 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

Guarumo 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 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Guarumo?

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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.