Drug & supplement interaction

American Pawpaw + 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 American Pawpaw 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

American Pawpaw 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 American Pawpaw 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.

American Pawpaw safety at a glance

American Pawpaw overall Use caution The ripe fruit is generally eaten as food, but concentrated leaf, twig, and seed extracts may be toxic and lack good safety data.

Pregnancy Avoid There is not enough safety information, and concentrated extracts may be harmful, so avoid during pregnancy.

Breastfeeding Avoid Safety has not been studied, so avoid concentrated pawpaw supplements while breastfeeding.

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

Still wondering about combining Letrozole and American Pawpaw? 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. American Pawpaw has documented interactions with 1 drug class — the most serious being antineoplastics (minor) — 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

American Pawpaw Does Interact With Other Medications

American Pawpaw has 25 minor known drug interactions in our database — Letrozole isn’t one of them. If you take anything else, check it against the full list below.

Minor 25 No known interaction 2,805 (incl. Letrozole)

Taking anything else?

Check Another of Your Medications Against American Pawpaw

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

What to actually watch for

No Interaction Found — But Data Suggests American Pawpaw 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.

Headache Additional detail
American Pawpaw
“In general, American pawpaw is well tolerated. However, cases of urticaria, nausea, vomiting, bowel disturbances, headache, and faintness have been reported following ingestion of pawpaw fruit. Similarly, American pawpaw extract may cause vomiting when taken orally or contact dermatitis when applied topically.”

American Pawpaw · Natural Medicines adverse-effect record, reported in cluster headache.
3 sources cited

89428. Barber MA. Poisoning due to the papaw (Asimina triloba). JAMA. 1905;XLV(27):2013-2014. DOI

89429. McLaughlin JL. Paw paw and cancer: Annonaceous acetogenins from discover to commercial products. J Nat Prod. 2008;71:1311-1321.

1525. Avalos J, Rupprecht JK, McLaughlin JL, et al. Guinea pig maximization test of the bark extract from pawpaw, Asimina triloba (Annonaceae). Contact Dermatitis 1993;29:33-5.
“Orally, American pawpaw fruit can cause headache and faintness.”

American Pawpaw · Natural Medicines adverse-effect record, reported in cluster headache.
1 source cited

89428. Barber MA. Poisoning due to the papaw (Asimina triloba). JAMA. 1905;XLV(27):2013-2014. DOI
Letrozole

Listed in the ADVERSE REACTIONS section of the FDA label for Letrozole. Read the label on DailyMed ›
Nausea Additional detail
American Pawpaw
“Orally, American pawpaw fruit can cause nausea, vomiting, bowel disturbances, and burning of the throat and stomach. American pawpaw extract can cause vomiting when taken orally.”

American Pawpaw · Natural Medicines adverse-effect record, reported in nausea and vomiting.
2 sources cited

89428. Barber MA. Poisoning due to the papaw (Asimina triloba). JAMA. 1905;XLV(27):2013-2014. DOI

89429. McLaughlin JL. Paw paw and cancer: Annonaceous acetogenins from discover to commercial products. J Nat Prod. 2008;71:1311-1321.
Letrozole

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

Reported for American Pawpaw but not commonly for Letrozole: a skin rash, hives and vomiting.

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

From our Q&A

Questions About American Pawpaw 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 American Pawpaw 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 American Pawpaw 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 American Pawpaw 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 American Pawpaw

Top half

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

What is American Pawpaw?

Anticancer interest
Lice and head lice treatment (topical)
Traditional digestive remedy
General wellness/antioxidant
Insecticide (historical seed use)

American pawpaw is a North American fruit tree whose leaves, twigs, and seeds contain compounds called acetogenins that have shown cancer-cell-killing activity in laboratory studies. However, strong human evidence for any health benefit is lacking, and the seeds, bark, and unripe parts can be toxic, so supplements should be used cautiously and only under professional guidance.

Asimina triloba · Annonaceae · Fruit, seeds, bark, leaves, and twigs · Fresh fruit, capsules, extracts, and standardized acetogenin products

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

American Pawpaw: dosing

There is no established standardized dose for American pawpaw supplements. Products vary widely in strength and which part of the plant they use, which makes safe dosing hard to determine.If you choose to use a pawpaw product, follow the directions on the label and do not exceed them.

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

Read the full American Pawpaw monograph & all interactions

Medication

About Letrozole

What Is Letrozole Used For?

Brand name: Femara

Letrozole (brand name Femara, or available as generic letrozole tablets) is used to treat breast cancer in postmenopausal women whose tumors are hormone receptor positive — meaning the cancer feeds on estrogen. It is used in several situations: as an adjuvant treatment (therapy given after primary treatment to reduce the risk of the cancer returning) for early breast cancer, and as extended adjuvant treatment for women who have already completed five years of tamoxifen therapy.

Femara and letrozole tablets are also used as first-line or second-line treatment for locally advanced or metastatic (spread to other areas) breast cancer in postmenopausal women, including cases where the cancer has progressed after other anti-estrogen therapy.

See full Letrozole drug information

Keep checking

Other Drugs & American Pawpaw

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

0Major

0Moderate

25Minor

2,804No known interaction

25 Minor 2,804 No interaction

Minor

25 interactions

No interaction 2,804 drugs checked — show the list

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

Showing the 60 most looked-up of 2,804 medications checked with no known interaction — see the full American Pawpaw list.

See the full American Pawpaw interactions page

See every supplement checked against Letrozole, ranked by severity

Evidence & sources

American Pawpaw References

The 4 references that drive our American Pawpaw 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.

Avalos J, Rupprecht JK, McLaughlin JL, et al. Guinea pig maximization test of the bark extract from pawpaw, Asimina triloba (Annonaceae). Contact Dermatitis 1993;29:33-5.
McCage, C. M., Ward, S. M., Paling, C. A., Fisher, D. A., Flynn, P. J., and McLaughlin, J. L. Development of a paw paw herbal shampoo for the removal of head lice. Phytomedicine 2002;9(8):743-748. PubMed
Barber MA. Poisoning due to the papaw (Asimina triloba). JAMA. 1905;XLV(27):2013-2014. DOI
McLaughlin JL. Paw paw and cancer: Annonaceous acetogenins from discover to commercial products. J Nat Prod. 2008;71:1311-1321.

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 American Pawpaw and Letrozole Together: Common Questions

Is it safe to take American Pawpaw with Letrozole?

We do not list a known interaction between American Pawpaw 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 American Pawpaw 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 American Pawpaw and Letrozole combination checked?

Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and American Pawpaw 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 American Pawpaw interact with any other medications?

Yes. American Pawpaw has 25 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 — American Pawpaw 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

American Pawpaw 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 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and American Pawpaw?

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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.