Toremifene
Toremifene is an estrogen-blocking (antiestrogen) cancer medicine used to treat metastatic breast cancer in postmenopausal women whose tumors are estrogen-receptor positive or unknown.
🧬 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 →
Toremifene (Fareston) is a hormone-blocking medicine for metastatic breast cancer (cancer that has spread) in postmenopausal women with estrogen-receptor positive or unknown tumors. It competes with estrogen at the tumor’s receptors to block estrogen’s growth signal, and it is a close cousin of tamoxifen, on the market since about 1997 and available as a generic, though prescribed far less often. Most people tolerate it reasonably well, with hot flashes and sweating the usual complaints, sometimes with nausea. Its boxed warning is QT prolongation, a heart rhythm change that can trigger a dangerous racing heartbeat, so fainting, a seizure or a fast, irregular heartbeat needs emergency help.
Clinical pearls
- Run every new medicine past your pharmacist, including some antibiotics and antifungals, heart rhythm drugs, St. John’s wort and grapefruit juice.
- Expect potassium, magnesium, calcium, liver and blood count checks, plus an ECG (heart tracing) if your heart risk is higher.
- Bone pain or redness around tumor areas in the first weeks can be tumor flare with high calcium, so call promptly.
- Report any vaginal bleeding and get a gynecologic exam before starting and yearly, since uterine cancer has been reported.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Toremifene can change your heart's electrical rhythm (QT prolongation), which can lead to a dangerous rapid heartbeat called Torsade de pointes. This can cause fainting, seizures, or death.
You should not take it if you have long QT syndrome, or low potassium or magnesium that hasn't been corrected. Medicines that also prolong the QT interval and strong CYP3A4 inhibitors should be avoided. Seek urgent help if you faint or have a seizure or racing, irregular heartbeat.
Patient information guide A plain-language walkthrough of Toremifene, written from its FDA label.
What Toremifene is used for
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Toremifene is used for one cancer indication across its supported products.
- Metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors (Fareston and toremifene citrate tablets, oral).
How Toremifene works
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Toremifene binds to estrogen receptors. Depending on the situation it can act like estrogen, block estrogen, or both. In breast cancer, its effect is believed to come mainly from blocking estrogen.
By competing with estrogen for binding sites in the tumor, it blocks estrogen's growth-stimulating effect.
Toremifene dosage
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Toremifene tablets are taken by mouth once a day. Food does not affect absorption, so you can take them with or without food.
Treatment generally continues until the disease progresses. Follow your prescriber's instructions and your label.
Dosing details from the FDA-approved label
From the Toremifene prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Toremifene citrate tablets (Fareston) – dosage
- 60 mg, once daily, orally
- Treatment is generally continued until disease progression is observed
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION The dosage of toremifene citrate tablets is 60 mg, once daily, orally. Treatment is generally continued until disease progression is observed. 60 mg once daily, orally ( 2 )
Read the full Dosage and Administration section on DailyMed →
Toremifene side effects
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Side effects mostly come from toremifene's antiestrogen action and often appear early in treatment.
Common side effects
- Hot flashes
- Sweating
- Nausea
- Vaginal discharge
- Dizziness
- Swelling (edema)
- Vomiting
- Vaginal bleeding
When to get medical help
- Fainting, seizure, or a fast, irregular heartbeat: these can signal a dangerous heart rhythm problem (QT prolongation). Get emergency help.
- Yellowing of the skin or eyes, or other signs of liver problems: call your doctor.
- New musculoskeletal pain with redness and growth of tumor areas in the first weeks, especially with bone metastases: this may be tumor flare, and calcium levels may be high. Call your doctor.
- Vaginal bleeding or other new gynecologic symptoms: tell your doctor, since uterine problems including endometrial cancer have been reported.
- Signs of a blood clot, such as sudden leg swelling or pain or sudden shortness of breath: seek medical help.
- Pregnancy while taking this medicine: call your doctor right away.
Toremifene warnings and precautions
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- QT prolongation (boxed warning): can cause a dangerous heart rhythm, fainting, seizure, or death.
- Liver problems: liver tests should be done periodically.
- High calcium and tumor flare: mainly in the first weeks, especially with bone metastases.
- Uterine problems: endometrial cancer, thickening, and polyps have been reported. Yearly gynecologic exams are advised.
- Blood counts: low white cells and platelets have been reported rarely.
- Pregnancy: can cause fetal harm.
Toremifene interactions
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Many drugs can change toremifene's levels or add to its heart rhythm effects.
- QT-prolonging drugs (certain antiarrhythmics, antipsychotics, antidepressants, antibiotics, anti-nausea drugs): added risk of dangerous heart rhythm.
- Strong CYP3A4 inhibitors (such as ketoconazole, itraconazole, ritonavir, voriconazole) and grapefruit juice: raise toremifene levels.
- Strong CYP3A4 inducers (such as rifampin, carbamazepine, phenytoin, St. John's Wort): lower toremifene levels.
- Thiazide diuretics: may raise the risk of high calcium.
- Warfarin or phenytoin: need careful monitoring.
Interactions listed in the FDA-approved label
From the Toremifene prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Drugs that decrease renal calcium excretion (e.g., thiazide diuretics): May increase the risk of hypercalcemia in patients receiving toremifene citrate tablets.
- Agents that prolong QT (e.g., Class 1A antiarrhythmics such as quinidine, procainamide, disopyramide; Class III antiarrhythmics such as amiodarone, sotalol, ibutilide, dofetilide; antipsychotics such as thioridazine, haloperidol; antidepressants such as venlafaxine, amitriptyline; antibiotics such as erythromycin, clarithromycin, levofloxacin, ofloxacin; ant: Agents that have demonstrated QT prolongation as one of their pharmacodynamic effects are generally accepted to prolong the QT interval. Should be avoided. If treatment with such an agent is required, interrupt toremifene therapy. If interruption is not possible, closely monitor for QT interval prolongation. In patients at increased risk, obtain ECGs and monitor as clinically indicated.
- Strong CYP3A4 inducers (e.g., dexamethasone, phenytoin, carbamazepine, rifampin, rifabutin, phenobarbital, St. John's Wort): Lower the steady-state concentration of toremifene in serum; may result in a relevant decrease in toremifene exposure. Should be avoided.
- Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole): Increase the steady-state concentration of toremifene in serum. In a study of 18 healthy subjects, 80 mg toremifene once daily with 200 mg ketoconazole twice daily increased toremifene Cmax and AUC by 1.4- and 2.9-fold, respectively; N-demethyltoremifene Cmax and AUC were reduced by 56% and 20%, respectively. Should be avoided. If treatment with such an agent is required, interrupt toremifene therapy. If interruption is not possible, closely monitor for QT interval prolongation.
- Grapefruit juice: May also increase plasma concentrations of toremifene. Should be avoided.
- CYP3A4 substrates (e.g., midazolam): Clinically relevant exposure changes in sensitive substrates due to inhibition or induction of CYP3A4 by toremifene appear unlikely; midazolam and α-hydroxymidazolam Cmax and AUC were reduced by less than 20% on day 18.
- CYP2C9 substrates with a narrow therapeutic index (e.g., warfarin, phenytoin): Toremifene is a weak inhibitor of CYP2C9; plasma tolbutamide Cmax and AUC were increased by less than 30% in a study of 20 healthy subjects. Use with caution and careful monitoring (e.g., substrate concentrations if possible, appropriate laboratory markers, and signs and symptoms of increased exposure).
Read the label’s full interactions text
7 DRUG INTERACTIONS Drugs that decrease renal calcium excretion, e.g., thiazide diuretics, may increase the risk of hypercalcemia in patients receiving toremifene citrate tablets. ( 7.1 ) Agents that prolong QT should be avoided. ( 7.2 ) Coadministration with a strong CYP3A4 inducer may result in a relevant decrease in toremifene citrate tablets exposure and should be avoided. ( 7.3 ) Coadministration with a strong CYP3A4 inhibitor can result in a relevant increase in toremifene citrate tablets exposure and should be avoided. ( 7.4 ) CYP2C9 substrates with a narrow therapeutic index such as warfarin or phenytoin with toremifene citrate tablets should be used with caution and require careful monitoring. ( 7.6 ) 7.1 Drugs that Decrease Renal Calcium Excretion Drugs that decrease renal calcium excretion, e.g., thiazide diuretics, may increase the risk of hypercalcemia in patients receiving toremifene citrate tablets. 7.2 Agents that Prolong QT The administration of toremifene citrate tablets with agents that have demonstrated QT prolongation as one of their pharmacodynamic effects should be avoided. Should treatment with any of these agents be required, it is recommended that therapy with toremifene citrate tablets be interrupted. If interruption of treatment with toremifene citrate tablets is not possible, patients who require treatment with a drug that prolongs QT should be closely monitored for prolongation of the QT interval. Agents generally accepted to prolong QT interval include Class 1A (e.g., quinidine, procainamide, disopyramide) and Class III (e.g., amiodarone, sotalol, ibutilide, dofetilide) antiarrhythmics; certain antipsychotics (e.g., thioridazine, haloperidol); certain antidepressants (e.g., venlafaxine, amitriptyline); certain antibiotics (e.g., erythromycin, clarithromycin, levofloxacin, ofloxacin); and certain anti-emetics (e.g., ondansetron, granisetron).
Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Toremifene
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- Do not use with long QT syndrome, uncorrected low potassium or magnesium, or known hypersensitivity.
- Use caution with heart failure, liver impairment, and electrolyte problems.
- Generally avoid with a history of blood clots.
- Pregnancy: it can harm the fetus. Premenopausal women should use effective non-hormonal contraception.
- Breastfeeding: your doctor will weigh stopping nursing or the drug.
- Children: no indication for use.
- Older adults: no significant age-related differences in effectiveness or safety were noted.
- Kidney impairment: pharmacokinetics were similar to those in normal kidney function.
Toremifene overdose
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Overdose may increase antiestrogenic effects such as hot flashes, estrogenic effects such as vaginal bleeding, or nervous system effects such as vertigo, dizziness, ataxia (unsteady movement), and nausea. There is no specific antidote, and treatment is symptomatic.
What Toremifene does in the body
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Toremifene shows antiestrogen activity and also some estrogen-like activity, such as lowering FSH and LH hormone levels. It increases the QTc interval in a dose- and concentration-related way. It did not affect heart rate, PR or QRS intervals.
How your body processes Toremifene
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Toremifene is well absorbed by mouth and food doesn't affect it. Peak levels occur within about 3 hours, and steady state takes about 4-6 weeks. It is broken down mainly by CYP3A4 to N-demethyltoremifene, which is also antiestrogenic. Its half-life is about 5 days, and it leaves mostly in the stool.
How to store Toremifene
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Store at 25°C (77°F). Protect from heat and light.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. 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.
Toremifene: pharmacist answers to common questions
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 is toremifene for?
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How do I take it?
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What side effects should I expect?
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What's the main safety concern?
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Do I need to watch what else I take?
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Can I take it if I might get pregnant?
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Is Toremifene available over the counter?
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When was Toremifene first available?
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Who makes Toremifene?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Toremifene on HelloPharmacist
Toremifene forms and strengths (how it 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.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Toremifene inactive ingredients by manufacturer.
Tablet
How this form is used
- Fareston is used to treat metastatic breast cancer in postmenopausal women with estrogen-receptor positive or unknown tumors.
- Toremifene citrate tablets are used for the same indication.
- Fareston is taken by mouth once daily.
- Toremifene citrate tablets are taken by mouth once daily, with or without food.
- Treatment with Fareston or toremifene citrate tablets generally continues until disease progression.
Toremifene on the U.S. market: products, makers and brands
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.
3 companies list 3 Toremifene product records with the FDA, mostly as tablet; the earliest marketing or approval year on record is 1997. Brand names on the directory include Fareston; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (2) — 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 (Medicaid data)
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 1,601 medications we measure, Toremifene ranks #1,535 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 | Novadoz Pharmaceuticals LLC | ANDA | View NDC → |
| 60 mg | Oral | Rising Pharma Holdings, Inc. | ANDA | View NDC → |
Showing 3 of 3 products — FDA National Drug Code Directory. See every product, package size and price: browse all 3 Toremifene NDCs →
Toremifene side effects reported to the 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.
Toremifene FDA approval history
How Toremifene went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Toremifene 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.
The FDA’s enforcement reports list no Toremifene recalls since July 2021.
✅No Toremifene recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
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
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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.
Toremifene supply and 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.
Toremifene brand names
Toremifene is sold under one brand name in the FDA directory — Fareston. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Toremifene: manufacturers and labelers
3 companies list Toremifene products with the FDA. By number of product records, the largest are Kyowa Kirin, Inc., Novadoz Pharmaceuticals LLC, Rising Pharma Holdings, Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Toremifene drug class (RxNorm)
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.
Sources for this Toremifene page
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 this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Kyowa Kirin, Inc, is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →