Toremifene
Toremifene is an estrogen-blocking medication used to treat metastatic breast cancer in postmenopausal women whose tumors are estrogen-receptor positive or of unknown receptor status.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 3 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Toremifene citrate tablets can cause a serious, potentially fatal heart rhythm problem. The drug lengthens a part of the heart's electrical cycle called the QT interval, in a way that increases with higher doses and higher drug levels in the blood. When the QT interval is too long, the heart can develop a dangerous rapid rhythm called Torsade de pointes — which can lead to fainting, seizures, or death. People who already have a long QT interval (inherited or from another cause), or who have uncorrected low potassium or low magnesium, must not take toremifene. Drugs that also prolong the QT interval, and strong drugs that raise toremifene blood levels (strong CYP3A4 inhibitors), must be avoided while on toremifene.
📖 Toremifene: Patient Information Guide
A plain-language walkthrough of Toremifene — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Toremifene is used to treat a specific type of advanced breast cancer. Both Fareston (branded) and toremifene citrate (generic) tablets are approved for the same indication:
- Fareston is indicated for metastatic breast cancer (breast cancer that has spread beyond the breast) in postmenopausal women whose tumors are estrogen-receptor positive or whose receptor status is unknown.
- Toremifene citrate tablets carry the same indication: metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors.
⚙️How it works▾
Toremifene is an estrogen agonist/antagonist — it can either block or weakly mimic estrogen depending on the tissue. In breast cancer, its main effect is antiestrogenic: it competes directly with estrogen for receptor binding sites on tumor cells, preventing estrogen from delivering its growth signal. By blocking that signal, toremifene slows or reverses tumor growth. It also shows mild estrogen-like activity in some tissues, which accounts for some of its hormonal side effects.
Toremifene is broken down in the liver mainly by an enzyme called CYP3A4 into a metabolite called N-demethyltoremifene, which also has antiestrogenic activity. Drugs that strongly affect CYP3A4 can meaningfully raise or lower toremifene's levels in the blood, which is why certain drug combinations must be avoided.
💊How it's taken▾
Toremifene citrate tablets are taken once daily by mouth. You can take them with or without food — eating does not change how much of the drug your body absorbs. Treatment is generally continued until the cancer progresses or your doctor advises otherwise. Always follow your prescriber's specific instructions, and do not adjust your dose on your own.
- Take at roughly the same time each day to maintain steady drug levels.
- It takes several weeks (about 4–6 weeks) for the drug to reach a stable concentration in your blood.
🤒Side effects — in detail▾
The most common side effects of toremifene are largely driven by its anti-estrogen activity and tend to appear early in treatment:
- Hot flashes
- Sweating
- Nausea
- Vaginal discharge
- Dizziness
- Swelling (edema)
- Vomiting
- Vaginal bleeding
Serious reactions — including dangerous heart rhythm changes, liver injury (jaundice, hepatitis), severe high calcium levels, or signs of a blood clot — require immediate medical attention. Contact your doctor or seek emergency care if any of these occur.
⚠️Warnings & precautions▾
- Heart rhythm (QT prolongation): Toremifene lengthens the QT interval in a dose-related way, raising the risk of a rare but life-threatening arrhythmia (Torsade de pointes) that can cause fainting, seizures, or death. Anyone with a pre-existing long QT condition, low potassium, or low magnesium must not take this drug. Other QT-prolonging drugs must be avoided.
- Liver toxicity (hepatotoxicity): Serious liver injury, including elevated liver enzymes, jaundice, and hepatitis, has been reported. Liver function tests should be checked periodically.
- Hypercalcemia and tumor flare: Some patients with bone metastases develop high blood calcium (hypercalcemia) and a temporary flare of symptoms (pain, redness, increased tumor size) in the first weeks. This flare does not mean the drug is failing. Severe hypercalcemia may require stopping the drug.
- Uterine risks: Endometrial cancer, uterine polyps, and uterine tissue changes have been reported. Regular gynecological exams are recommended.
- Blood clots: Patients with a history of blood clots (thromboembolism) should generally not use toremifene.
- Pregnancy harm: Toremifene can cause serious fetal harm. Women who could become pregnant must use effective non-hormonal contraception.
🔀What it interacts with▾
Toremifene has several important drug and food interactions that can increase serious risks or reduce its effectiveness:
- QT-prolonging drugs (e.g., certain antiarrhythmics like amiodarone, quinidine; antipsychotics like thioridazine, haloperidol; antidepressants like amitriptyline, venlafaxine; antibiotics like erythromycin, clarithromycin, levofloxacin; anti-nausea drugs like ondansetron) — combining these with toremifene raises the risk of a dangerous heart rhythm and should be avoided.
- Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir, clarithromycin, nefazodone, voriconazole, and others) — raise toremifene blood levels significantly, increasing risk of QT prolongation; avoid if possible.
- Grapefruit juice — can increase toremifene blood levels and should be avoided.
- Strong CYP3A4 inducers (e.g., rifampin, carbamazepine, phenytoin, phenobarbital, St. John's Wort) — lower toremifene levels in the blood, potentially reducing how well it works; avoid if possible.
- Thiazide diuretics (water pills) — may worsen high calcium levels in patients at risk.
- Warfarin and phenytoin (and other narrow therapeutic index CYP2C9 substrates) — toremifene weakly inhibits the enzyme that clears these drugs, so their levels may rise; careful monitoring is required.
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Do not take toremifene if you have a known long QT syndrome (inherited or acquired heart electrical problem).
- Do not take toremifene if you have uncorrected low potassium (hypokalemia) or low magnesium (hypomagnesemia) — these electrolyte imbalances must be fixed first.
- Tell your doctor if you have heart failure or any other heart condition — extra caution and monitoring are needed.
- Tell your doctor if you have liver disease (such as cirrhosis) — toremifene is cleared more slowly and may require closer monitoring.
- Tell your doctor if you have a history of blood clots — toremifene is generally not recommended in this situation.
- Tell your doctor if you have bone metastases — you will need close monitoring for high calcium levels early in treatment.
- Pregnancy: Toremifene can harm an unborn baby. Do not use during pregnancy. If you could become pregnant, use effective non-hormonal contraception throughout treatment.
- Breastfeeding: It is not known if toremifene passes into human breast milk, but the potential for serious harm to a nursing infant means you should not breastfeed while taking this drug.
- Children: There is no approved use of toremifene in pediatric patients.
- Older adults: Studies in elderly women showed the drug stays in the body somewhat longer, but no clinically significant differences in effectiveness or safety were found in clinical trials.
- Tell your doctor about all medications you take — especially heart drugs, antifungals, antibiotics, anticonvulsants, and blood thinners.
🚑If you take too much▾
Taking too much toremifene may cause worsened antiestrogenic effects (such as severe hot flashes), estrogen-like effects (such as vaginal bleeding), or nervous system symptoms like dizziness, vertigo, nausea, vomiting, and in severe cases, hallucinations or loss of coordination (ataxia). There is no specific antidote — treatment focuses on managing symptoms. If you think you or someone else has taken too much, contact emergency services or a poison control center immediately.
📡Pharmacodynamics — effects in the body▾
Toremifene blocks estrogen's effect on breast cancer cells by competing with estrogen for receptor binding sites, which is its main therapeutic action. It also has measurable antiestrogenic effects in other tissues — for example, it reduces certain markers of estrogen activity in postmenopausal women. At the same time, it shows mild estrogen-like effects elsewhere in the body, such as lowering levels of certain reproductive hormones (FSH and LH). Importantly, toremifene prolongs the heart's QT interval in a dose- and concentration-dependent way, which is the basis of its most serious safety warning.
🔬Pharmacokinetics — how your body processes it▾
Toremifene is well absorbed after swallowing a tablet, with peak blood levels reached within about 3 hours, and food does not affect absorption. It is very extensively bound to blood proteins (over 99.5%) and is broken down mainly by a liver enzyme called CYP3A4 into active metabolites. The drug has a long elimination half-life of about 5 days, and it takes roughly 4–6 weeks of daily dosing to reach steady concentrations in the blood. Toremifene is cleared primarily through the stool (feces) as metabolites, with only about 10% leaving the body via urine; its elimination is slowed by a recycling process between the liver and gut (enterohepatic circulation). Liver impairment can extend how long the drug stays in the body, while kidney impairment does not significantly affect its clearance.
📦How to store it▾
Store at 25°C (77°F). Protect from heat and light.
📄 Written from Toremifene’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Toremifene
143 supplements and herbal products have documented interactions with Toremifene in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 3
- Moderate · 101
- Minor · 39
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Toremifene — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is toremifene treating — and how does it work against my breast cancer? ▾
Do I need to take this with food, and does it matter what time of day I take it? ▾
What side effects should I expect, and which ones should make me call my doctor right away? ▾
I take a few other medications. Are there any I need to watch out for? ▾
Is it safe to get pregnant or breastfeed while on toremifene? ▾
My doctor mentioned something about my heart rhythm — why does that matter with this medication? ▾
Is Toremifene available over the counter? ▾
When was Toremifene first available? ▾
Who makes Toremifene? ▾
💬 Answers drafted from Toremifene’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Toremifene comes
Toremifene is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Tablet
How this form is used
- Fareston (toremifene citrate) tablet is indicated for metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors
- Toremifene citrate tablet is indicated for metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors
- Fareston and toremifene citrate tablets are taken once daily by mouth
- Toremifene citrate tablets may be taken with or without food — meals do not affect absorption
- Fareston treatment is generally continued until the disease progresses, as directed by your prescriber
- Swallow the tablet whole and take it at roughly the same time each day to keep drug levels steady
📊 Toremifene across the U.S. market
How Toremifene appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (3) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Toremifene is used
A general measure of how commonly Toremifene is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Toremifene is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Toremifene prescribed? Of the 1,594 medications we measure, Toremifene ranks #1,534 by Medicaid prescriptions — more than 4% of them.
Utilization by Toremifene product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
toremifene 60 MG Oral Tablet
Summed across the 1 of 6 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 313428
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Toremifene, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 6 listed Toremifene NDCs with Medicaid activity.
🔍 Compare Toremifene products
A representative set of FDA-listed product records for Toremifene — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 60 mg | Oral | Kyowa Kirin, Inc, | NDA | View NDC → |
| 60 mg | Oral | Kyowa Kirin, Inc. × 2 listings | NDA | View NDC → |
| 60 mg | Oral | Msn Laboratories Private Limited | ANDA | View NDC → |
| 60 mg | Oral | Novadoz Pharmaceuticals LLC × 2 listings | ANDA | View NDC → |
| 60 mg | — | Orion Corporation, Orion Pharma | DRUG FOR FURTHER PROCESSING | View NDC → |
| 60 mg | Oral | Rising Pharmaceuticals, Inc. | ANDA | View NDC → |
| 60 mg | Oral | Rising Pharma Holdings, Inc. | ANDA | View NDC → |
| 💊Bulk drug substance | ||||
| 1 g/g | — | AX Pharmaceutical Corp | BULK INGREDIENT FOR HUMAN PRESCRIPTION COMPOUNDING | View NDC → |
| 1 kg/kg | — | MSN Laboratories Private Limited | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Qingdao Tida Biotek Co.,ltd | BULK INGREDIENT FOR HUMAN PRESCRIPTION COMPOUNDING | View NDC → |
Showing 12 of 12 products — FDA National Drug Code Directory. See every product, package size and price: browse all 12 Toremifene NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Toremifene — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Toremifene in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Toremifene went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 38409 1 dose form · 1 strength
-
Dose form (SCDF) Oral Tablet RxCUI 374167In current FDA listingsClinical drug / strength (SCD) 60 MGRxCUI 313428
Look up RxCUI 38409 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Toremifene is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Toremifene belongs to the Estrogen Agonist/Antagonist class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 3 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Kyowa Kirin, Inc, is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.