Generic Name: toremifene (tor EH mih feen)
Brand Name: Fareston
What is Fareston (toremifene)?
Toremifene blocks estrogen from reaching cancer cells. Certain types of breast cancer require estrogen to grow.
Toremifene is used in postmenopausal women to treat metastatic breast cancer (cancer that has spread to other parts of the body).
Toremifene may also be used for purposes not listed in this medication guide.
What is the most important information I should know about Fareston (toremifene)?
You should not use toremifene if you have a history of Long QT syndrome, or low levels of potassium or magnesium in your blood.
Toremifene can cause a life-threatening heart rhythm disorder. Stop using toremifene and call your doctor at once if you have: headache with chest pain and severe dizziness, fainting, and fast or pounding heartbeats.
What should I discuss with my healthcare provider before taking Fareston (toremifene)?
You should not use toremifene if you are allergic to it, or if you have:
a history of Long QT syndrome; or
an uncontrolled electrolyte imbalance (low levels of potassium or magnesium in your blood).
To make sure toremifene is safe for you, tell your doctor if you have:
a family history of long QT syndrome;
high levels of calcium in your blood (hypercalcemia);
endometrial hyperplasia (overgrowth of cells lining the uterus);
bone cancer; or
if you have ever had a blood clot.
Taking toremifene may increase your risk of developing endometrial hyperplasia, a condition that may lead to cancer of the uterus. Talk to your doctor about your individual risk.
Do not use toremifene if you are pregnant. It could harm the unborn baby. Use effective birth control if you are not past menopause, and tell your doctor if you become pregnant during treatment.
It is not known whether toremifene passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using toremifene.
How should I take Fareston (toremifene)?
Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
You may take toremifene with or without food. Take the medicine at the same time each day.
While using toremifene, you may need frequent blood tests. Your liver function may also need to be checked.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid while taking Fareston (toremifene)?
Grapefruit and grapefruit juice may interact with toremifene and lead to unwanted side effects. Avoid the use of grapefruit products while taking toremifene.
This medicine can pass into body fluids (including urine, feces, vomit, semen, vaginal fluid). Patients and caregivers should wear rubber gloves while cleaning up body fluids, handling contaminated trash or laundry or changing diapers. Wash hands before and after removing gloves. Wash soiled clothing and linens separately from other laundry.
Body fluids should not be handled by a woman who is pregnant or who may become pregnant. Use condoms during sexual activity to avoid exposure to body fluids.
Fareston (toremifene) side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Toremifene can cause a life-threatening heart rhythm disorder. Stop using toremifene and call your doctor at once if you have:
headache with chest pain and severe dizziness;
a light-headed feeling, like you might pass out;
seizure (convulsions); or
fast or pounding heartbeats.
Also call your doctor at once if you have:
slow heart rate, weak pulse, fainting, slow breathing (breathing may stop);
blurred vision, tunnel vision, eye pain, or seeing halos around lights;
heart attack symptoms--chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating;
high levels of calcium in your blood--nausea, vomiting, constipation, increased thirst or urination, muscle weakness, bone pain, confusion, lack of energy or tired feeling;
signs of a stroke--sudden numbness or weakness (especially on one side of the body), sudden severe headache, slurred speech, problems with vision or balance; or
signs of a blood clot in the lung--chest pain, sudden cough, wheezing, rapid breathing, coughing up blood.
Common side effects may include:
sweating, hot flashes;
abnormal liver function tests.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
What other drugs will affect Fareston (toremifene)?
Many drugs can interact with toremifene. Not all possible interactions are listed here. Tell your doctor about all your medications and any you start or stop using during treatment with toremifene, especially:
anagrelide, imatinib, methadone, nefazodone, ondansetron, St. John's wort, warfarin (Coumadin, Jantoven);
an antibiotic--azithromycin, clarithromycin, erythromycin, levofloxacin, moxifloxacin, pentamidine, telithromycin;
an antidepressant--citalopram, escitalopram;
antifungal medicine--itraconazole, ketoconazole, posaconazole, voriconazole;
anti-malaria medication--chloroquine, halofantrine;
antiviral medicine to treat hepatitis C or HIV/AIDS--atazanavir, boceprevir, cobicistat (Stribild, Tybost), delavirdine, fosamprenavir, indinavir, nelfinavir, ritonavir, saquinavir, telaprevir;
cancer medicine--arsenic trioxide, vandetanib, vemurafenib;
heart medicine--amiodarone, disopyramide, dofetilide, dronedarone, flecainide, ibutilide, quinidine, sotalol;
medicine to treat a psychiatric disorder--chlorpromazine, haloperidol, pimozide, thioridazine;
seizure medicine--carbamazepine, fosphenytoin, oxcarbazepine, phenobarbital, phenytoin, primidone; or
tuberculosis medicine--isoniazid, rifabutin, rifampin, rifapentine.
This list is not complete and there are many other drugs that can interact with toremifene. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor. Keep a list of all your medicines and show it to any healthcare provider who treats you.
More about Fareston (toremifene)
Related treatment guides
Where can I get more information?
- Your pharmacist can provide more information about toremifene.
- Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
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