Drug & supplement interaction

Inositol + 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 Inositol 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

Inositol 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 Inositol 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.

Inositol safety at a glance

Inositol overall Generally safe Generally well tolerated at common doses, with mostly mild digestive side effects.
Pregnancy Possibly Safe When used orally and appropriately, short-term. Myo-inositol has been used with apparent safety in amounts up to 4000 mg daily during pregnancy. Read the full pregnancy detail
Breastfeeding Use caution There is not enough reliable information, so use caution and check with your doctor.

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 Inositol? 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. Inositol has documented interactions with 1 drug class — the most serious being antidiabetes 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

Inositol Does Interact With Other Medications

Inositol has 86 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 86 No known interaction 2,744 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Inositol

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

What to actually watch for

No Interaction Found — But Data Suggests Inositol 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.

  • Tiredness / Dizziness / Headache Additional detail

    Inositol

    “Orally, inositol may cause dizziness, tiredness, insomnia, agitation, and headache. In combination with omega-3 fatty acids, inositol has been associated with reports of feelings of thirst in children in clinical research.”

    Inositol · Natural Medicines adverse-effect record, reported in cluster headache.

    4 sources cited
    1. 10387. Palatnik A, Frolov K, Fux M, Benjamin J. Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol 2001;21:335-9.. PubMed
    2. 11972. Allan SJ, Kavanagh GM, Herd RM, Savin JA. The effect of inositol supplements on the psoriasis of patients taking lithium: a randomized, placebo-controlled trial. Br J Dermatol 2004;150:966-9. PubMed
    3. 95089. Leppink EW, Redden SA, Grant JE. A double-blind, placebo-controlled study of inositol in trichotillomania. Int Clin Psychopharmacol. 2017;32(2):107-14. PubMed
    4. 95092. Wozniak J, Faraone SV, Chan J, et al. A randomized clinical trial of high eicosapentaenoic acid omega-3 fatty acids and inositol as monotherapy and in combination in the treatment of pediatric bipolar spectrum disorders: a pilot study. J Clin Psychiatry. PubMed

    Letrozole

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

  • Nausea Additional detail

    Inositol

    “Orally, inositol may cause nausea, diarrhea, gas, and gastrointestinal discomfort.”

    Inositol · Natural Medicines adverse-effect record, reported in diarrhea.

    6 sources cited
    1. 10387. Palatnik A, Frolov K, Fux M, Benjamin J. Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol 2001;21:335-9.. PubMed
    2. 11972. Allan SJ, Kavanagh GM, Herd RM, Savin JA. The effect of inositol supplements on the psoriasis of patients taking lithium: a randomized, placebo-controlled trial. Br J Dermatol 2004;150:966-9. PubMed
    3. 91547. Kamenov Z, Kolarov G, Gateva A, Carlomagno G, Genazzani AD. Ovulation induction with myo-inositol alone and in combination with clomiphene citrate in polycystic ovarian syndrome patients with insulin resistance. Gynecol Endocrinol 2015;31(2):131-5. PubMed
    4. 91549. Mukai T, Kishi T, Matsuda Y, Iwata N. A meta-analysis of inositol for depression and anxiety disorders. Hum Psychopharmacol 2014;29(1):55-63. PubMed
    5. 95089. Leppink EW, Redden SA, Grant JE. A double-blind, placebo-controlled study of inositol in trichotillomania. Int Clin Psychopharmacol. 2017;32(2):107-14. PubMed
    6. 95090. Lam S, Mandrekar SJ, Gesthalter Y. A Randomized Phase IIb Trial of myo-Inositol in Smokers with Bronchial Dysplasia. Cancer Prev Res (Phila). 2016;9(12):906-14.

    Letrozole

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

Reported for Inositol but not commonly for Letrozole: stomach upset, anxiety or restlessness, diarrhea and trouble sleeping.

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

Inositol in Pregnancy & Breastfeeding

Pregnancy Possibly Safe

When used orally and appropriately, short-term. Myo-inositol has been used with apparent safety in amounts up to 4000 mg daily during pregnancy.

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

We hold 10,116 real supplement products containing Inositol, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Inositol. Even though Inositol 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 Inositol 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 Inositol
Top 5%

#24 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 Inositol reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Inositol and Letrozole records this page draws on were last updated July 11, 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 Inositol

What is Inositol?

Inositol
  • Polycystic ovary syndrome (PCOS)
  • Anxiety and panic
  • Depression and mood
  • Insulin and blood sugar support
  • Fertility support
  • Metabolic syndrome

Inositol is a sugar alcohol made naturally in the body and found in many foods, and it is sold as a supplement (often myo-inositol) mainly for PCOS, mood, and metabolic concerns. The strongest evidence is for PCOS-related symptoms, while support for other uses is more limited. It is generally well tolerated, but talk with your pharmacist or doctor before starting it, especially if you are pregnant or have a health condition.

Not applicable (a sugar alcohol found in foods and made by the body) · Capsules, tablets, powder (often as myo-inositol or D-chiro-inositol)

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

Inositol: dosing

There is no single official or standardized dose of inositol for general health. Do not assume that higher doses are better or safer.

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

Read the full Inositol 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 & Inositol

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

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

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Inositol list.

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

Inositol References

The 14 references that drive our Inositol 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. Palatnik A, Frolov K, Fux M, Benjamin J. Double-blind, controlled, crossover trial of inositol versus fluvoxamine for the treatment of panic disorder. J Clin Psychopharmacol 2001;21:335-9.. PubMed
  2. Allan SJ, Kavanagh GM, Herd RM, Savin JA. The effect of inositol supplements on the psoriasis of patients taking lithium: a randomized, placebo-controlled trial. Br J Dermatol 2004;150:966-9. PubMed
  3. Machado-Vieira R, Viale CI, Kapczinski F. Mania associated with an energy drink: the possible role of caffeine, taurine, and inositol. Can J Psychiatry 2001;46:454-5. PubMed
  4. Kamenov Z, Kolarov G, Gateva A, Carlomagno G, Genazzani AD. Ovulation induction with myo-inositol alone and in combination with clomiphene citrate in polycystic ovarian syndrome patients with insulin resistance. Gynecol Endocrinol 2015;31(2):131-5. PubMed
  5. Matarrelli B, Vitacolonna E, D'Angelo M, et al. Effect of dietary myo-inositol supplementation in pregnancy on the incidence of maternal gestational diabetes mellitus and fetal outcomes: a randomized controlled trial. J Matern Fetal Neonatal Med 2013;26(1 PubMed
  6. Mukai T, Kishi T, Matsuda Y, Iwata N. A meta-analysis of inositol for depression and anxiety disorders. Hum Psychopharmacol 2014;29(1):55-63. PubMed
  7. Farren M, Daly N, McKeating A, Kinsley B, Turner MJ, Daly S. The Prevention of Gestational Diabetes Mellitus With Antenatal Oral Inositol Supplementation: A Randomized Controlled Trial. Diabetes Care. 2017;40(6):759-63. PubMed
  8. Zheng X, Liu Z, Zhang Y, et al. Relationship Between Myo-Inositol Supplementary and Gestational Diabetes Mellitus: A Meta-Analysis. Medicine (Baltimore). 2015;94(42):e1604. PubMed
  9. Crawford TJ, Crowther CA, Alsweiler J, Brown J. Antenatal dietary supplementation with myo-inositol in women during pregnancy for preventing gestational diabetes. Cochrane Database Syst Rev. 2015;(12):CD011507. PubMed
  10. Maurizi AR, Menduni M, Del Toro R, et al. A pilot study of D-chiro-inositol plus folic acid in overweight patients with type 1 diabetes. Acta Diabetol. 2017;54(4):361-65. PubMed
  11. Leppink EW, Redden SA, Grant JE. A double-blind, placebo-controlled study of inositol in trichotillomania. Int Clin Psychopharmacol. 2017;32(2):107-14. PubMed
  12. Lam S, Mandrekar SJ, Gesthalter Y. A Randomized Phase IIb Trial of myo-Inositol in Smokers with Bronchial Dysplasia. Cancer Prev Res (Phila). 2016;9(12):906-14.
  13. Wozniak J, Faraone SV, Chan J, et al. A randomized clinical trial of high eicosapentaenoic acid omega-3 fatty acids and inositol as monotherapy and in combination in the treatment of pediatric bipolar spectrum disorders: a pilot study. J Clin Psychiatry. PubMed
  14. Vitale SG, Corrado F, Caruso S, et al. Myo-inositol supplementation to prevent gestational diabetes in overweight non-obese women: bioelectrical impedance analysis, metabolic aspects, obstetric and neonatal outcomes - a randomized and open-label, placebo-

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 Inositol and Letrozole Together: Common Questions

Is it safe to take Inositol with Letrozole?
We do not list a known interaction between Inositol 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 Inositol and Letrozole have any of the same side effects?
Yes — our sources link each of them separately to 4 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 Inositol and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Inositol 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 Inositol interact with any other medications?
Yes. Inositol has 86 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 — Inositol 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

Inositol 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 14 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Inositol?

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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.