Drug & supplement interaction

Strontium + 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 Strontium 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

Strontium 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 Strontium 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.

Strontium safety at a glance

Strontium overall Use caution Strontium has been linked to serious heart and clotting risks, especially the ranelate form.
Pregnancy Likely Safe When consumed orally in food amounts. Strontium has not been linked to toxicity when consumed in dietary amounts, which are typically about 0.5 mg to 1.5 mg/day... Read the full pregnancy detail
Breastfeeding Likely Safe When consumed orally in food amounts. Strontium has not been linked to toxicity when consumed in dietary amounts, which are typically about 0.5 mg to 1.5 mg/day... Read the full breastfeeding detail

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 Strontium? 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. Strontium has documented interactions with 5 drug classes — the most serious being androgens (moderate), antacids (moderate) and estrogens (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

Strontium Does Interact With Other Medications

Strontium has 101 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 101 No known interaction 2,729 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Strontium

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

What to actually watch for

No Interaction Found — But Data Suggests Strontium 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

    Strontium

    “Orally, strontium ranelate seems to be well tolerated when used in doses up to 2 grams (680 mg elemental strontium) daily, long-term.

    Most Common Adverse Effects:

    Orally: Atopic dermatitis, diarrhea, headache, nausea.

    Serious Adverse Effects (Rare):

    Orally: Myocardial infarction, osteomalacia, venous thromboembolism.”

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

    Letrozole

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

  • Nausea Additional detail

    Strontium

    “Orally, strontium ranelate can cause stomach pain, diarrhea, and nausea, particularly at higher doses.”

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

    4 sources cited
    1. 14561. O'Donnell S, Cranney A, Wells GA, et al. Strontium ranelate for preventing and treating postmenopausal osteoporosis. Cochrane Musculoskeletal Group. Cochrane Database Syst Rev 2006;(4):CD005326. PubMed
    2. 76541. O'Donnell, S., Cranney, A., Wells, G. A., Adachi, J. D., and Reginster, J. Y. Strontium ranelate for preventing and treating postmenopausal osteoporosis. Cochrane.Database.Syst.Rev. 2006;3:CD005326. PubMed
    3. 94010. Rizzoli R, Chapurlat RD, Laroche JM, et al. Effects of strontium ranelate and alendronate on bone microstructure in women with osteoporosis. Results of a 2-year study. Osteoporosis Int. 2012. 23(1):305-315. doi: 10.1007/s00198-011-1758-z. PubMed
    4. 94012. Reginster JY, Kaufman JM, Goemaere S, et al. Maintenance of antifracture efficacy over 10 years with strontium ranelate in postmenopausal osteoporosis. Osteoporos Int. 2012;23(3):1115-1122. doi: 10.1007/s00198-011-1847-z. PubMed

    Letrozole

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

Reported for Strontium but not commonly for Letrozole: blood clots, a heart attack, stomach pain and bone thinning.

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

Strontium in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When consumed orally in food amounts. Strontium has not been linked to toxicity when consumed in dietary amounts, which are typically about 0.5 mg to 1.5 mg/day. ...when strontium chloride is used topically and appropriately as a toothpaste. Strontium chloride hexahydrate (Sensodyne-SC) is an FDA approved product.

Pregnancy And Lactation Likely Unsafe

When strontium-89 chloride is used during pregnancy or lactation. Strontium-89 chloride is a radioactive isotope which may cause fetal harm. It is FDA pregnancy risk category D; avoid using. Since strontium behaves similarly to calcium in the body, strontium-89 is likely to be excreted into breast milk; avoid using during lactation. There is insufficient reliable information about the safety of oral strontium when used in amounts exceeding typical dietary intake during pregnancy or lactation; avoid using.

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

Overlapping uses

What Letrozole Is Prescribed For, and What Strontium 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. Strontium 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.

Strontium has been studied for:

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

    Strontium for cancer

    Although there has been interest in using oral strontium for metastatic cancer, there is insufficient reliable information about the clinical effects of strontium for this purpose.

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 Strontium for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

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

We hold 347 real supplement products containing Strontium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Strontium. Even though Strontium 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 Strontium 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 Strontium
Top half

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

What is Strontium?

  • Bone health and osteoporosis
  • Reducing fracture risk
  • Tooth sensitivity (in some toothpastes)
  • Supporting bone density

Strontium is a mineral that has been studied mainly for bone health and osteoporosis. The prescription form (strontium ranelate) showed benefit for fracture risk but carries serious heart-related safety concerns, while the over-the-counter supplement form (strontium citrate) has much less evidence. Talk to your doctor or pharmacist before using it, especially if you have heart disease or are at risk for blood clots.

Mineral element (not a plant) · Capsules and tablets, usually as strontium citrate or strontium ranelate (prescription in some countries)

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

Strontium: dosing

There is no firmly established dose for over-the-counter strontium supplements. Strontium and calcium compete for absorption, so they are usually taken at different times of day. Do not assume more is better, since higher amounts may increase risks.

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

Read the full Strontium 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 & Strontium

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

0Major
101Moderate
0Minor
2,728No known interaction
101 Moderate 2,728 No interaction
Moderate

101 interactions

Showing 60 of 101 moderate interactions — see all 101 on the Strontium page.

No interaction 2,728 drugs checked — show the list

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

Showing the 60 most looked-up of 2,728 medications checked with no known interaction — see the full Strontium list.

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

Strontium References

The 22 references that drive our Strontium 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. Martindale W. Martindale the Extra Pharmacopoeia. Pharmaceutical Press, 1999.
  2. Meunier PJ, Roux C, Seeman E, et al. The effects of strontium ranelate on the risk of vertebral fracture in women with postmenopausal osteoporosis. N Engl J Med 2004;350:459-68.. PubMed
  3. El-Hajj Fuleihan G. Strontium ranelate--a novel therapy for osteoporosis or a permutation of the same? N Engl J Med 2004;350:504-6. PubMed
  4. Verberckmoes SC, De Broe ME, D'Haese PC. Dose-dependent effects of strontium on osteoblast function and mineralization. Kidney Int 2003;64:534-43. . PubMed
  5. Meunier PJ, Slosman DO, Delmas PD, et al. Strontium ranelate: dose-dependent effects in established postmenopausal vertebral osteoporosis--a 2-year randomized placebo controlled trial. J Clin Endocrinol Metab 2002;87:2060-6.. DOI
  6. Brandi ML. New treatment strategies: ipriflavone, strontium, vitamin D metabolites and analogs. Am J Med 1993;95:69S-74S. . PubMed
  7. Eisenberg E. Effects of androgens, estrogens and corticoids on strontium kinetics in man. J Clin Endocrinol Metab 1966;26:566-72.
  8. Metastron prescribing information. Medi-Physics, Inc., Amersham Healthcare, Arlington Heights, IL, 1998. http://www.cancerpaintherapy.com/METATECHPAGE.htm. (Accessed 13 March 2004).
  9. Protelos European Summary of Product Characteristics. Les Laboratoires Servier, 2006. Available at: www.servier.com/pro/osteoporose/protelos/protelos_spc.asp. (Accessed 01 August 2006).
  10. US Department of Health and Human Services, Public Health Service. Agency for Toxic Substances and Disease Registry. Toxicological profile for strontium. April 2004. Available at: www.atsdr.cdc.gov/toxprofiles/tp159.pdf. (Accessed 8 August 2006).
  11. Apostolidis N, Paradellis T, Karydas A, et al. Calcium and strontium metabolic studies in patients on CAPD. Perit Dial Int 1998;18:410-4. DOI
  12. Ozgur S, Sumer H, Kocoglu G. Rickets and soil strontium. Arch Dis Child 1996;75:524-6. PubMed
  13. Schrooten I, Elseviers MM, Lamberts LV, et al. Increased serum strontium levels in dialysis patients: an epidemiological survey. Kidney Int 1999;56:1886-92. PubMed
  14. D'Haese PC, Couttenye MM, Lamberts LV, et al. Aluminum, iron, lead, cadmium, copper, zinc, chromium, magnesium, strontium, and calcium content in bone of end-stage renal failure patients. Clin Chem 1999;45:1548-56. DOI
  15. Pennington JA, Jones JW. Molybdenum, nickel, cobalt, vanadium, and strontium in total diets. J Am Diet Assoc 1987;87:1644-50. DOI

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 Strontium and Letrozole Together: Common Questions

Is it safe to take Strontium with Letrozole?
We do not list a known interaction between Strontium 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 Strontium 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.
Are Strontium 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 Strontium in each. That is a conversation for your prescriber, especially if Letrozole is being adjusted to a target.
How was the Strontium and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Strontium has documented interactions with 5 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 Strontium interact with any other medications?
Yes. Strontium has 101 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 — Strontium 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

Strontium 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 22 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Strontium?

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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.