Streptococcus Thermophilus + Letrozole
Letrozole brand name: Femara.
We found no known interaction between Streptococcus Thermophilus 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.
Streptococcus Thermophilus 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 Streptococcus Thermophilus 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.
Worth understanding: our licensed dataset holds no drug-interaction record for Streptococcus Thermophilus at all — not against Letrozole, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.
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.
Streptococcus Thermophilus safety at a glance
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.
Streptococcus Thermophilus in Pregnancy & Breastfeeding
When used orally and appropriately, short-term. A combination of Streptococcus thermophilus, Lactobacillus acidophilus, Bifidobacterium animalis, and Lactobacillus delbrueckii has been used with apparent safety for 8 weeks starting at 24-28 weeks gestation.
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
Questions About Streptococcus Thermophilus 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 Streptococcus Thermophilus 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.
See Every Supplement That Interacts With Letrozole
This page covers Streptococcus Thermophilus 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
Taking Streptococcus Thermophilus as Part of a Dietary Supplement Product? Check It for Interactions
We hold 1,450 real supplement products containing Streptococcus Thermophilus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Streptococcus Thermophilus. Even though Streptococcus Thermophilus 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:
Where Streptococcus Thermophilus 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.
#191 of 1,452 supplements looked up here in the last 7 days
#50 of 2,830 medications looked up here in the last 7 days
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 Streptococcus Thermophilus reference on this page ↓
- Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Streptococcus Thermophilus 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.
About Streptococcus Thermophilus
What is Streptococcus Thermophilus?
- Digestive health
- Lactose intolerance
- Diarrhea prevention and support
- Gut microbiome balance
- Immune support
Streptococcus thermophilus is a friendly bacterium used as a probiotic, often combined with other strains in yogurt and supplements. It is generally well tolerated in healthy people and may help with digestion and lactose breakdown, but solid evidence for most specific health claims is still limited. Talk with your pharmacist or doctor before starting it, especially if your immune system is weak.
Streptococcus thermophilus · Streptococcaceae · Live bacterial cells (probiotic culture) · Capsules, powders, probiotic blends, yogurt, fermented dairy products
An interaction check asks whether these two react with each other — it does not ask whether Streptococcus Thermophilus is a good idea for someone in your situation. Here is what our Streptococcus Thermophilus record says about it on its own.
Streptococcus Thermophilus: dosing
There is no single official or standardized dose for Streptococcus thermophilus. Probiotic products are usually measured in colony-forming units (CFU), and amounts vary widely between products.The best approach is to follow the dosing directions on the product label, since formulas differ.
From our Streptococcus Thermophilus monograph — the full record covers uses, side effects and every documented interaction.
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.
Other Drugs & Streptococcus Thermophilus
Browse every other medication we’ve checked against Streptococcus Thermophilus — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
No interaction 2,829 drugs checked — show the list
We also checked Streptococcus Thermophilus against these medications and found no known interaction in our sources. Open any page to confirm.
- Apixaban ›
- Levothyroxine ›
- Amlodipine ›
- Methylphenidate ›
- Warfarin ›
- Sertraline ›
- Testosterone ›
- Losartan Potassium ›
- Metoprolol ›
- Aspirin ›
- Ivermectin ›
- Rivaroxaban ›
- Rosuvastatin ›
- Escitalopram ›
- Tadalafil ›
- Acetaminophen ›
- Clopidogrel ›
- Valacyclovir ›
- Atorvastatin ›
- Docusate ›
- Hydroxyurea ›
- Abemaciclib ›
- Methamphetamine ›
- Sumatriptan ›
- Ibuprofen ›
- Semaglutide ›
- Tirzepatide ›
- Warfarin Sodium ›
- Prednisone ›
- Propranolol ›
- Lisdexamfetamine ›
- Acyclovir ›
- Bupropion ›
- Metformin ›
- Amoxicillin ›
- Lisinopril ›
- Bendamustine ›
- Amitriptyline ›
- Doxycycline ›
- Lamotrigine ›
- Fluoxetine ›
- Methotrexate ›
- Acetaminophen, Codeine ›
- Gabapentin ›
- Amphetamine ›
- Pregabalin ›
- Isotretinoin ›
- Dextroamphetamine ›
- Azithromycin ›
- Clonazepam ›
- Quetiapine ›
- Omeprazole ›
- Amlodipine Besylate ›
- Methylene Blue ›
- Duloxetine ›
- Buspirone ›
- Citalopram ›
- Ciprofloxacin ›
- Naproxen ›
- Bisoprolol ›
Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Streptococcus Thermophilus list.
Streptococcus Thermophilus References
The 21 references that drive our Streptococcus Thermophilus 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.
- Saxelin M, Chuang NH, Chassy B, et al. Lactobacilli and bacteremia in southern Finland 1989-1992. Clin Infect Dis 1996;22:564-6. PubMed
- Tynkkynen S, Singh KV, Varmanen P. Vancomycin resistance factor of Lactobacillus rhamnosus GG in relation to enterococcal vancomycin resistance (van) genes. Int J Food Microbiol 1998;41:195-204. PubMed
- Klein G, Zill E, Schindler R, et al. Peritonitis associated with vancomycin-resistant Lactobacillus rhamnosus in a continuous ambulatory peritoneal dialysis patient; organism identification, antibiotic therapy, and case report. J Clin Microbiol 1998;36:
- Kalima P, Masterton RG, Roddie PH, et al. Lactobacillus rhamnosus infection in a child following bone marrow transplant. J Infect 1996;32:165-7. PubMed
- Goldin BR. Health Benefits of probiotics. Br J Nutr 1998;80:S203-7. DOI
- Rautio M, Jousimies-Somer H, Kauma H, et al. Liver abscess due to Lactobacillus rhamnosus strain indistinguishable from L. rhamnosus strain GG. Clin Infect Dis 1999;28:1159-60.
- MacGregor G, Smith AJ, Thakker B, Kinsella J. Yoghurt biotherapy: contraindicated in immunosuppressed patients? Postgrad Med J 2002;78:366-7. PubMed
- Land MH, Rouster-Stevens K, Woods CR, et al. Lactobacillus sepsis associated with probiotic therapy. Pediatrics 2005;115:178-81.
- De Groote MA, Frank DN, Dowell E, et al. Lactobacillus rhamnosus GG bacteremia associated with probiotic use in a child with short gut syndrome. Pediatr Infect Dis J 2005;24:278-80. PubMed
- Vahabnezhad E, Mochon AB, Wozniak LJ, Ziring DA. Lactobacillus bacteremia associated with probiotic use in a pediatric patient with ulcerative colitis. J Clin Gastroenterol. 2013;47(5):437-9. PubMed
- Dolatkhah N, Hajifaraji M, Abbasalizadeh F, Aghamohammadzadeh N, Mehrabi Y, Abbasi MM. Is there a value for probiotic supplements in gestational diabetes mellitus? A randomized clinical trial. J Health Popul Nutr. 2015;33:25. PubMed
- Pruccoli G, Silvestro E, Pace Napoleone C, Aidala E, Garazzino S, Scolfaro C. Are probiotics safe? Bifidobacterium bacteremia in a child with severe heart failure. Infez Med. 2019;27(2):175-178.
- Sendil S, Shrimanker I, Mansoora Q, Goldman J, Nookala VK. Lactobacillus rhamnosus bacteremia in an immunocompromised renal transplant patient. Cureus. 2020;12(2):e6887. PubMed
- Albarillo FS, Shah U, Joyce C, Slade D. Lactobacillus rhamnosus Infection: A single-center 4-year descriptive analysis. J Glob Infect Dis. 2020;12(3):119-123. PubMed
- Pasala S, Singer L, Arshad T, Roach K. Lactobacillus endocarditis in a healthy patient with probiotic use. IDCases. 2020;22:e00915. PubMed
- Agrawal S, Tuchman ES, Bruce MJ, Theodorou ME. Fatal Lactobacillus endocarditis in a patient with transcatheter aortic valve replacement. BMJ Case Rep. 2020;13(11):e236835.
- Antoun M, Hattab Y, Akhrass FA, Hamilton LD. Uncommon pathogen, Lactobacillus, causing infective endocarditis: Case report and review. Case Rep Infect Dis. 2020;2020:8833948. PubMed
- Rossi F, Amadoro C, Gasperi M, Colavita G. Lactobacilli infection case reports in the last three years and safety implications. Nutrients. 2022;14(6):1178. PubMed
- Franko B, Vaillant M, Recule C, Vautrin E, et al. Lactobacillus paracasei endocarditis in a consumer of probiotics. Med Mal Infect. 2013;43(4):171-3. PubMed
- Campbell RE, Miller A, Afroze A. Native valve endocarditis secondary to Lactobacillus paracasei bacteremia. Consultant. 2020;60(9):27-8. DOI
- Kato K, Funabashi N, Takaoka H, et al. Lactobacillus paracasei endocarditis in a consumer of probiotics with advanced and severe bicuspid aortic valve stenosis complicated with diffuse left ventricular mid-layer fibrosis. Int J Cardiol. 2016;224:157-161. 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.
Taking Streptococcus Thermophilus and Letrozole Together: Common Questions
Is it safe to take Streptococcus Thermophilus with Letrozole?
Does Letrozole interact with any supplements?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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