Shark Cartilage + Letrozole
Letrozole brand name: Femara.
We found no known interaction between Shark Cartilage 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.
Shark Cartilage 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 Shark Cartilage 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.
Shark Cartilage safety at a glance
Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
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. Shark Cartilage has documented interactions with 1 drug class — the most serious being immunosuppressants (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.
Shark Cartilage Does Interact With Other Medications
Shark Cartilage has 121 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.
Check Another of Your Medications Against Shark Cartilage
We haven’t checked that one against Shark Cartilage yet — ask our pharmacists directly.
Covers the 2,830 medications we’ve checked against Shark Cartilage. Pick one to open its full report.
What Letrozole Is Prescribed For, and What Shark Cartilage 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. Shark Cartilage 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.
Shark Cartilage has been studied for:
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Cancer studied, not established Shark Cartilage has been studied for this. Natural Medicines rates the evidence: Likely Ineffective Read what the research shows
Shark Cartilage for cancer
Most clinical research shows that oral shark cartilage is not beneficial in people with advanced cancer.
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 Shark Cartilage for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.
Questions About Shark Cartilage 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 Shark Cartilage 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 Shark Cartilage 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 Shark Cartilage as Part of a Dietary Supplement Product? Check It for Interactions
We hold 2 real supplement products containing Shark Cartilage, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Shark Cartilage. Even though Shark Cartilage 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 Shark Cartilage 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.
#687 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 Shark Cartilage reference on this page ↓
- Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Shark Cartilage 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.
About Shark Cartilage
What is Shark Cartilage?
- Cancer support (popular use)
- Arthritis and joint pain
- Psoriasis
- Wound healing
- General immune support
Shark cartilage is a supplement made from the skeletal tissue of sharks that was heavily promoted for cancer and joint conditions, but good-quality clinical trials have not shown meaningful benefit. It is generally not recommended, and there are real environmental and safety concerns, so talk with your doctor or pharmacist before considering it.
Cartilage (skeletal tissue) from sharks, often from species such as the spiny dogfish and hammerhead · Capsules, tablets, powder
An interaction check asks whether these two react with each other — it does not ask whether Shark Cartilage is a good idea for someone in your situation. Here is what our Shark Cartilage record says about it on its own.
Shark Cartilage: dosing
There is no established or standardized dose for shark cartilage, and products vary widely in their content and quality. Studies have used very different amounts and forms, so no reliable recommended dose exists.If you are considering shark cartilage despite the limited evidence, follow the directions on the product label and do not exceed them.
From our Shark Cartilage 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 & Shark Cartilage
Browse every other medication we’ve checked against Shark Cartilage — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
121 interactions
- Hydrocortisone ›
- Prednisone ›
- Cyclosporine ›
- Dexamethasone ›
- Prednisolone ›
- Tacrolimus ›
- Triamcinolone ›
- Betamethasone ›
- Ciclesonide ›
- Azathioprine ›
- Beclomethasone ›
- Beclomethasone Dipropionate ›
- Cladribine ›
- Cortisone Acetate ›
- Cyclophosphamide ›
- Daclizumab ›
- Denosumab ›
- Fingolimod ›
- Methylprednisolone ›
- Tofacitinib ›
- Triamcinolone Acetonide ›
- 6-mercaptopurine ›
- Abatacept ›
- Abrocitinib ›
- Adalimumab ›
- Adalimumab-adaz ›
- Adalimumab-adbm ›
- Adalimumab-afzb ›
- Adalimumab-atto ›
- Adalimumab-bwwd ›
- Adalimumab-fkjp ›
- Alefacept ›
- Alemtuzumab ›
- Anifrolumab-fnia ›
- Antithymocyte Globulin ›
- Atezolizumab ›
- Azamune ›
- Basiliximab ›
- Beclometasone Dipropionate ›
- Betamethasone Dipropionate ›
- Betamethasone Valerate ›
- Bimekizumab-bkzx ›
- Cisplatin ›
- Copanlisib ›
- Deflazacort ›
- Deucravacitinib ›
- Diroximel Fumarate ›
- Durvalumab ›
- Eculizumab ›
- Efalizumab ›
- Efgartigimod Alfa-fcab ›
- Elranatamab ›
- Emapalumab-lzsg ›
- Epcoritamab-bysp ›
- Etanercept ›
- Etanercept-szzs ›
- Etanercept-ykro ›
- Etrasimod ›
- Fludrocortisone ›
- Fluorouracil (iv) ›
Showing 60 of 121 moderate interactions — see all 121 on the Shark Cartilage page.
No interaction 2,708 drugs checked — show the list
We also checked Shark Cartilage 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 ›
- 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 ›
- Levothyroxine, Liothyronine ›
Showing the 60 most looked-up of 2,708 medications checked with no known interaction — see the full Shark Cartilage list.
Shark Cartilage References
The 12 references that drive our Shark Cartilage 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.
- Ashar B, Vargo E. Shark cartilage-induced hepatitis [letter]. Ann Intern Med 1996;125:780-1. PubMed
- Lane IW, Comac L. Sharks don't get cancer. Garden City, NY: Avery Publishing Group; 1992.
- Miller DR, Anderson GT, Stark JJ, et al. Phase I/II trial of the safety and efficacy of shark cartilage in the treatment of advanced cancer. J Clin Oncol 1998;16:3649-55. PubMed
- Leitner SP, Rothkopf MM, Haverstick L, et al. Two phase II studies of oral dry shark cartilage powder (SCP) in patients (pts) with either metastatic breast or prostate cancer refractory to standard treatment. Proc Am Soc Clinical Oncol 1998;17:A240.
- Batist G, Patenaude F, Champagne P, et al. Neovastat (AE-941) in refractory renal cell carcinoma patients: report of a phase II trial with two dose levels. Ann Oncol 2002;13:1259-63..
- Merly, L., Simjee, S., and Smith, S. L. Induction of inflammatory cytokines by cartilage extracts. Int Immunopharmacol. 2007;7(3):383-391. PubMed
- Bargahi, A., Hassan, Z. M., Rabbani, A., Langroudi, L., Noori, S. H., and Safari, E. Effect of shark cartilage derived protein on the NK cells activity. Immunopharmacol.Immunotoxicol. 2011;33(3):403-409. PubMed
- Leitner SP, Rothkopf MM, Haverstick DD, and et al. Two phase II studies of oral dry shark cartilage powder (SCP) in patients with either metastatic breast or prostate cancer refractory to standard treatment. Amer Soc Clin Oncol 1998;17:A240.
- Milner M. A guide to the use of shark cartilage in the treatment of arthritis and other inflammatory joint diseases. Amer Chiropractor 1999;21:40-42.
- Rosenbluth, RJ, Jennis, AA, Cantwell, S, and et al. Oral shark cartilage in the treatment of patients with advanced primary brain tumors. A phase II pilot study (meeting abstract). Proc Annu Meet Am Soc Clin Oncol 1999;18:A554.
- Saad F, Klotz L, Babaian R, Lacombe L, Champagne P, and Dupont E. Phase I/II trial on AE-941 (Neovastat) in patients with metastatic refractory prostate cancer (abstract presentation). Canadian Urological Association Annual Meeting (June 24-27, 2001).
- Merly L, Smith SL. Pro-inflammatory properties of shark cartilage supplement. Immunopharmacol Immunotoxicol. 2015;37(2):140-7. 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 Shark Cartilage and Letrozole Together: Common Questions
Is it safe to take Shark Cartilage with Letrozole?
Do Shark Cartilage and Letrozole have any of the same side effects?
Are Shark Cartilage and Letrozole used for the same thing?
How was the Shark Cartilage and Letrozole combination checked?
Does Shark Cartilage interact with any other medications?
Does Letrozole interact with any supplements?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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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.