Drug & supplement interaction

Lychee + 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 Lychee 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

Lychee 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 Lychee 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.

Lychee safety at a glance

Lychee overall Use caution The fruit is generally safe as food, but concentrated extracts are not well studied and unripe fruit carries specific risks.
Pregnancy Use caution Eating lychee fruit in normal food amounts is likely fine, but concentrated extracts have not been studied and should be avoided.
Breastfeeding Use caution Lychee as a food is likely fine, but there is not enough safety data on extracts during breastfeeding.

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

Still wondering about combining Letrozole and Lychee? 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. Lychee has documented interactions with 2 drug classes — the most serious being antidiabetes drugs (moderate) and immunosuppressants (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

Lychee Does Interact With Other Medications

Lychee has 86 moderate, 121 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.

Moderate 86 Minor 121 No known interaction 2,623 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Lychee

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

What to actually watch for

No Interaction Found — But Data Suggests Lychee and Letrozole May Share a Side Effect

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.

  • Swelling Additional detail

    Lychee

    “Orally, lychee can cause allergic reactions such as urticaria, dermatitis, tongue and lip swelling, shortness of breath, and anaphylaxis.

    Topically, contact with lychee fruit can cause allergic contact dermatitis.”

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

    4 sources cited
    1. 26955. Niggemann B, Reibel S, Hipler C, Wahn U. Anaphylactic reaction to lychee in a 12-year-old girl: cross-reactivity to latex? Pediatr Allergy Immunol 2002;13(1):64-7. PubMed
    2. 26956. Giannattasio M, Serafini M, Guarrera P, et al. Contact urticaria from litchi fruit (Litchi chinensis Sonn.). Contact Dermatitis 1995;33(1):67.
    3. 26957. Raap U, Schaefer T, Kapp A, Wedi B. Exotic food allergy: anaphylactic reaction to lychee. J Investig Allergol Clin Immunol 2007;17(3):199-201.
    4. 96614. Valsecchi R, Leghissa P. Contact allergy due to lychee. Acta Derm Venereol. 2013;93(1):90-1. PubMed

    Letrozole

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

Reported for Lychee but not commonly for Letrozole: shortness of breath, an allergic reaction, a severe allergic reaction and a skin rash.

Effects for Letrozole come from the ADVERSE REACTIONS section of its FDA label; effects for Lychee 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 Lychee 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 Lychee 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 Lychee 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 Lychee as Part of a Dietary Supplement Product? Check It for Interactions

We hold 98 real supplement products containing Lychee, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lychee. Even though Lychee 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 Lychee 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 Lychee
Top half

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

What is Lychee?

  • General nutrition and antioxidant support
  • Digestive complaints (traditional use)
  • Cough and sore throat (traditional use)
  • Blood sugar support (preliminary)
  • Weight and metabolic support (preliminary)

Lychee is a sweet tropical fruit that is nutritious and a source of vitamin C and antioxidant plant compounds. While the fruit is a healthy food for most people, supplement-strength extracts have only limited research behind specific health claims, and eating large amounts of unripe lychee on an empty stomach has been linked to dangerous low blood sugar in undernourished children. Talk to your pharmacist or doctor before using lychee extracts for any health condition.

Litchi chinensis · Sapindaceae · Fruit (pulp), seed, and peel; sometimes flowers and leaves · Fresh or dried fruit, juice, extract capsules, seed powder, teas

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

Lychee: dosing

There is no established standard dose for lychee supplements or extracts. The fruit itself can be eaten as a normal part of the diet in moderation.If you use a lychee extract or capsule product, follow the directions on the product label, and do not exceed the recommended amount.

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

Read the full Lychee 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 & Lychee

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

0Major
86Moderate
121Minor
2,622No known interaction
86 Moderate 121 Minor 2,622 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Lychee page.

Minor

121 interactions

Showing 60 of 121 minor interactions — see all 121 on the Lychee page.

No interaction 2,622 drugs checked — show the list

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

Showing the 60 most looked-up of 2,622 medications checked with no known interaction — see the full Lychee list.

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

Lychee References

The 12 references that drive our Lychee 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. Niggemann B, Reibel S, Hipler C, Wahn U. Anaphylactic reaction to lychee in a 12-year-old girl: cross-reactivity to latex? Pediatr Allergy Immunol 2002;13(1):64-7. PubMed
  2. Giannattasio M, Serafini M, Guarrera P, et al. Contact urticaria from litchi fruit (Litchi chinensis Sonn.). Contact Dermatitis 1995;33(1):67.
  3. Raap U, Schaefer T, Kapp A, Wedi B. Exotic food allergy: anaphylactic reaction to lychee. J Investig Allergol Clin Immunol 2007;17(3):199-201.
  4. Guo JW. Effects of Litchi seed on enhancing insulin sensitivity in type 2 diabetic-insulin resistant rats. Chinese J New Drugs 2003;12:526-9.
  5. Zhao M, Yang B, Wang J, et al. Immunomodulatory and anticancer activities of flavonoids extracted from litchi (Litchi chinensis Sonn) pericarp. Int Immunopharmacol 2007;7(2):162-6. PubMed
  6. John TJ, Das M. Outbreaks of Hypoglycemic Encephalopathy in Muzaffarpur, India: Are These Caused by Toxins in Litchi Fruit?: The Point. Indian Pediatr. 2016;53(5):399.
  7. John TJ. Exploration of Association between Litchi Consumption and Seasonal Acute Encephalopathy Syndrome: Pediatric Infectious Disease Specialist's Viewpoint. Indian Pediatr. 2017;54(4):323-325. DOI
  8. Mathew JL. Exploration of Association between Litchi Consumption and Seasonal Acute Encephalopathy Syndrome: Evidence-based Medicine Viewpoint. Indian Pediatr. 2017;54(4):319-323. PubMed
  9. Shrivastava A, Kumar A, Thomas JD, et al. Association of acute toxic encephalopathy with litchi consumption in an outbreak in Muzaffarpur, India, 2014: a case-control study. Lancet Glob Health. 2017;5(4):e458-e466.
  10. Spencer PS, Palmer VS, Mazumder R. Probable toxic cause for suspected lychee-linked viral encephalitis. Emerg Infect Dis. 2015;21(5):904-5. DOI
  11. Valsecchi R, Leghissa P. Contact allergy due to lychee. Acta Derm Venereol. 2013;93(1):90-1. PubMed
  12. Vashishtha VM. Outbreaks of Hypoglycemic Encephalopathy in Muzaffarpur, India: Are These Caused by Toxins in Litchi Fruit?: The Counterpoint. Indian Pediatr. 2016 May 8;53(5):399-402.

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 Lychee and Letrozole Together: Common Questions

Is it safe to take Lychee with Letrozole?
We do not list a known interaction between Lychee 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 Lychee and Letrozole have any of the same side effects?
Yes — our sources link each of them separately to one 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 Lychee and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Lychee has documented interactions with 2 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 Lychee interact with any other medications?
Yes. Lychee has 207 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 — Lychee 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

Lychee 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 12 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Lychee?

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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.