Toremifene may cause QT prolongation (an irregular heart rhythm that can lead to fainting, loss of consciousness, seizures, or sudden death). Tell your doctor if you or anyone in your family has or has ever had long QT syndrome (an inherited condition in which a person is more likely to have QT prolongation) or you have or have ever had low levels of potassium or magnesium in your blood, an irregular heartbeat, heart failure, or liver disease.
Tell your doctor and pharmacist if you are taking amitriptyline (Elavil); antifungals such as ketoconazole (Nizoral), itraconazole (Sporanox), or voriconazole (Vfend); clarithromycin (Biaxin, in Prevpac); erythromycin (E.E.S., E-Mycin, Erythrocin); granisetron (Kytril); haloperidol (Haldol); certain medications for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) such as atazanavir (Reyataz), indinavir (Crixivan), nelfinavir (Viracept), ritonavir (Norvir, in Kaletra), and saquinavir (Invirase); certain medications for irregular heartbeat such as amiodarone (Cordarone, Pacerone), disopyramide (Norpace), dofetilide (Tikosyn), ibutilide (Corvert), procainamide (Procanbid, Pronestyl), quinidine, and sotalol (Betapace, Betapace AF); levofloxacin (Levaquin); nefazodone; ofloxacin; ondansetron (Zofran); telithromycin (Ketek); thioridazine; and venlafaxine (Effexor).
If you experience any of the following symptoms, stop taking toremifene and call your doctor immediately: fast, pounding, or irregular heartbeat; fainting; loss of consciousness; or seizures.
Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body’s response to toremifene. Your doctor also may order electrocardiograms (EKGs, tests that record the electrical activity of the heart) before and during your treatment to be sure that it is safe for you to take toremifene.
Talk to your doctor about the risks of taking toremifene.
Why is Toremifene prescribed?
Toremifene is used to treat breast cancer that has spread to other parts of the body in women who have experienced menopause (‘change of life’; end of monthly menstrual periods).
Toremifene is in a class of medications called nonsteroidal antiestrogens. It works by blocking the activity of estrogen (a female hormone) in the breast. This may stop the growth of some breast tumors that need estrogen to grow.
How should Toremifene be used?
Toremifene comes as a tablet to take by mouth. It is usually taken with or without food once a day. Take toremifene at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take toremifene exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Other uses for Toremifene
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
What special precautions should I follow?
Before taking toremifene
- tell your doctor and pharmacist if you are allergic to toremifene, any other medications, or any of the ingredients in toremifene tablets. Ask your pharmacist for a list of the ingredients.
- tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention the medications listed in the IMPORTANT WARNING section and any of the following: anticoagulants (”blood thinners”) such as warfarin (Coumadin); carbamazepine (Epitol, Equetro, Tegretol); cimetidine (Tagamet); clonazepam (Klonopin); dexamethasone (Decadron, Dexone); diltiazem (Cardizem, Dilacor, Tiazac, others); diuretics (‘water pills’); fluvoxamine; phenobarbital; phenytoin (Dilantin, Phenytek); rifabutin (Mycobutin); rifampin (Rifadin, Rimactane); and verapamil (Calan, Covera, Isoptin, Verelan). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with toremifene, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
- tell your doctor what herbal products you are taking, especially St. John’s wort.
- tell your doctor if your cancer has spread to your bones and if you have or have ever had any condition that causes your blood to clot more easily than normal or endometrial hyperplasia (overgrowth of the lining of the uterus).
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking toremifene, call your doctor. Toremifene may harm the fetus. If you have not experienced menopause, you should use a reliable nonhormonal method of birth control to prevent pregnancy while you are taking toremifene.
- if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking toremifene.
- you should know that your tumor may grow slightly bigger when you begin treatment with toremifene. If this happens, you may experience redness of the skin and bone pain. This is normal and does not mean that your cancer is worsening. As you continue your treatment with toremifene, your tumor will shrink.
What special dietary instructions should I follow?
Do not eat grapefruit or drink grapefruit juice while you are taking this medicine.
What should I do if I forget a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
What side effects can Toremifene cause?
Toremifene may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- hot flashes
- blurred or abnormal vision
- sensitivity to light or seeing halos around lights
- difficulty seeing at night
- fading or yellowing of colors
- dry eyes
- swelling of the hands, feet, ankles, or lower legs
Serious side effects
If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:
- vaginal bleeding
- pelvic pain or pressure
- irregular periods
- unusual vaginal discharge
- muscle pain or weakness
- joint pain
- abdominal pain
- frequent urination
- excessive thirst
- loss of appetite
Some people who took toremifene developed cancer of the lining of the uterus. There is not enough information to tell if toremifene caused these people to develop cancer. Talk to your doctor about the risks of taking this medication.
Toremifene may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.
Storage and disposal of Toremifene
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat, and moisture (not in the bathroom).
Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.
It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org
In case of emergency/overdose
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.
Symptoms of overdose may include the following:
- hallucinations (seeing things or hearing voices that do not exist)
- hot flashes
- vaginal bleeding
What other information should I know?
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
Last Revised – 01/15/2018
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