Drug & supplement interaction

Tocotrienols + 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 Tocotrienols 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

Tocotrienols 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 Tocotrienols 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.

Tocotrienols safety at a glance

Tocotrienols overall Use caution Generally well tolerated in studies, but long-term safety at supplement doses is not well established.
Pregnancy Avoid Not enough safety information, so it is best to avoid supplemental doses during pregnancy.
Breastfeeding Use caution Little is known about safety while breastfeeding, so avoid supplements unless advised by your doctor.

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

Still wondering about combining Letrozole and Tocotrienols? 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. Tocotrienols has documented interactions with 1 drug class — the most serious being anticoagulant/antiplatelet drugs (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

Tocotrienols Does Interact With Other Medications

Tocotrienols has 122 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 122 No known interaction 2,708 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Tocotrienols

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

What to actually watch for

What Tocotrienols Itself Has Been Linked To

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

  • Itching Additional detail

    “Topically, a cream containing 5% tocotrienols has been reported to cause mild itching in 7% of patients in one clinical study. Contact dermatitis has been reported in 33% of patients using a cream containing vitamin E as a mixture of tocopherols and tocotrienols. However, it is unclear if this effect resulted from tocopherols, tocotrienols, or the combination.”

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

    2 sources cited
    1. 99699. Khoo TL, Halim AS, Zakaria Z, Mat Saad AZ, Wu LY, Lau HY. A prospective, randomised, double-blinded trial to study the efficacy of topical tocotrienol in the prevention of hypertrophic scars. J Plast Reconstr Aesthet Surg. 2011 Jun;64(6):e137-45. Epub 201 PubMed
    2. 4721. Baumann LS, Spencer JS. The effects of topical vitamin E on the cosmetic appearance of scars. Dermatol Surg 1999;25:311-5. PubMed
  • A skin rash Additional detail

    Recorded for Tocotrienols in the same Natural Medicines adverse-effect record shown under Itching above.

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

Overlapping uses

What Letrozole Is Prescribed For, and What Tocotrienols Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Letrozole is a prescription medicine with approved uses on its FDA label. Tocotrienols is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Letrozole is prescribed for: 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.

Tocotrienols has been studied for:

  • Breast cancer studied, not established Tocotrienols has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Tocotrienols for breast cancer

    It is unclear if oral tocotrienols are beneficial for improving early breast cancer outcomes or preventing recurrence.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Letrozole on your own; if you are taking Tocotrienols for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Tocotrienols 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 Tocotrienols 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 Tocotrienols 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 Tocotrienols as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1 real supplement products containing Tocotrienols, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Tocotrienols. Even though Tocotrienols 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 Tocotrienols 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 Tocotrienols
Top 25%

#278 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Letrozole
Top 5%

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

What is Tocotrienols?

Tocotrienols
  • Heart and cholesterol support
  • Antioxidant support
  • Liver health (fatty liver)
  • Bone health
  • Brain and nerve protection

Tocotrienols are a less common form of vitamin E with strong antioxidant activity studied mostly for cholesterol, liver, and heart health. Early research is interesting but far from conclusive, and a standard dose is not established. They are generally well tolerated, but talk with your pharmacist or doctor before using them, especially during pregnancy or if you take blood thinners.

Oil and extracts from plant seeds, bran, and fruits (such as rice bran, palm fruit, and annatto) · Softgel capsules, oil, combination vitamin E supplements

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

Tocotrienols: dosing

There is no official or standardized dose of tocotrienols. Amounts used in research have varied widely depending on the source and the condition being studied.The best approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full Tocotrienols 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 & Tocotrienols

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

0Major
0Moderate
122Minor
2,707No known interaction
122 Minor 2,707 No interaction
Minor

122 interactions

Showing 60 of 122 minor interactions — see all 122 on the Tocotrienols page.

No interaction 2,707 drugs checked — show the list

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

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Tocotrienols list.

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

Tocotrienols References

The 4 references that drive our Tocotrienols 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. Mensink RP, van Houwelingen AC, Kromhout D, Hornstra G. A vitamin E concentrate rich in tocotrienols had no effect on serum lipids, lipoproteins, or platelet function in men with mildly elevated serum lipid concentrations. Am J Clin Nutr 1999;69:213-9. PubMed
  2. Baumann LS, Spencer JS. The effects of topical vitamin E on the cosmetic appearance of scars. Dermatol Surg 1999;25:311-5. PubMed
  3. Khoo TL, Halim AS, Zakaria Z, Mat Saad AZ, Wu LY, Lau HY. A prospective, randomised, double-blinded trial to study the efficacy of topical tocotrienol in the prevention of hypertrophic scars. J Plast Reconstr Aesthet Surg. 2011 Jun;64(6):e137-45. Epub 201 PubMed
  4. Slivka A, Rink C, Paoletto D, Sen CK. Platelet function in stroke/transient ischemic attack patients treated with tocotrienol. FASEB J. 2020;34(9):11838-11843. 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 Tocotrienols and Letrozole Together: Common Questions

Is it safe to take Tocotrienols with Letrozole?
We do not list a known interaction between Tocotrienols 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.
Are Tocotrienols and Letrozole used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Tocotrienols in each. That is a conversation for your prescriber, especially if Letrozole is being adjusted to a target.
How was the Tocotrienols and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Tocotrienols 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 Tocotrienols interact with any other medications?
Yes. Tocotrienols has 122 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 — Tocotrienols 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

Tocotrienols 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 Tocotrienols?

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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.