Toremifene is used to treat certain types of breast cancer. It blocks growth of breast tissue that needs estrogen to grow. The most common side effects are hot flashes, sweathing, nausea, and vaginal discharge. Talk with your healthcare provider right away about any unusual vaginal bleeding, pelvic pain or pressure, or change in your monthly periods.

Uses

What is toremifene used for?

Toremifene is commonly used to treat certain types of breast cancer.

Toremifene may also be used for other conditions as determined by your healthcare provider.

How does toremifene work (mechanism of action)?

Toremifene blocks estrogen activity in some tissues. It is thought that toremifene binds to estrogen receptors blocking growth of breast tissue that needs estrogen to grow.

How is toremifene supplied (dosage forms)?

Brands and other names

  • Fareston

Dosage forms and strengths

  • 60 mg oral tablets

How should I store toremifene?

Toremifene should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect from light.

Side Effects

What are the most common side effects of toremifene?

The most common side effects of toremifene are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Hot flashes
  • Sweating
  • Nausea
  • Vaginal discharge

There may be other side effects of toremifene that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of toremifene?

While less common, the most serious side effects of toremifene are described below, along with what to do if they happen.

Severe Allergic Reactions. Toremifene may cause allergic reactions, which can be serious. Stop taking toremifene and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Heart Rhythm Changes. Toremifene may cause a rare, dangerous heart rhythm problem called QT prolongation and torsade de pointes. Some people have a higher risk of this, including people who are older, have other people in their family who have had these conditions, have low potassium or magnesium levels, or who take some medicines for other heart rhythm problems. Tell your healthcare provider right away if you faint or have changes in your heart rate or rhythm, such as a fast or skipping heartbeat. 

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking toremifene. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Blood Clots. Toremifene may cause blood clots in your arteries or veins and could cause a stroke, heart attack, or venous thromboembolism, including a blood clot in the lungs (pulmonary embolism) or deep venous thrombosis (DVT). Stop taking toremifene and get emergency help if you have any of the following signs of blood clots.

  • Chest pain or pressure
  • Fast or abnormal heartbeat
  • Trouble breathing
  • Pain in your back, jaw, throat, or arm
  • Sweating, upset stomach, vomiting, or dizziness
  • Sudden weakness on one side of your body
  • Sudden and severe headache
  • Slurred speech or trouble understanding speech
  • Pain, swelling, or tenderness in your arm or leg
  • Vision loss
  • Bulging eyes 
  • Double vision

Uterine Cancer. You may be at higher risk for problems with your uterus, including cancer of the uterus (womb) or cancer in the lining of your uterus (endometrial cancer) if you take or have taken toremifene. Call your healthcare provider right away if you have any abnormal vaginal bleeding, discharge, or pelvic pain or pressure. 

Eye Problems. Toremifene can increase your chance of developing cataracts, needing cataract surgery, or other eye problems. Tell your healthcare provider if you notice changes in your vision or things start to seem blurry.

Warnings & Precautions

Who should not use toremifene?

Allergies to Ingredients. People who are allergic to any of the following should not take toremifene.

  • Toremifene
  • Fareston
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific toremifene products they stock.

QT Prolongation. People with heart rhythm change known as QT prolongation or long QT syndrome should not take toremifene.

Low Blood Potassium Levels (Hypokalemia). People with low blood potassium levels should not take toremifene.

Low Blood Magnesium Levels (Hypomagnesemia). People with low blood magnesium levels should not take toremifene.

What should I know about toremifene before using it?

Do not take toremifene unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share toremifene with other people, even if they have the same condition as you. It may harm them.

Keep toremifene out of the reach of children.

Take toremifene once a day. It can be taken with or without food.

If you have not gone through menopause yet, you should use an effective birth control option that does not have hormones in it while you take toremifene. Some examples of non-hormonal birth control options include condoms and an intrauterine device (IUD) that does not have progesterone in it, such as a copper IUD. 

If your breast cancer has spread to your bones (meaning you have bone metastases), your healthcare provider will likely tell you about tumor flare and high blood calcium levels and what to watch for. Your healthcare provider may also monitor you more closely when you first start taking toremifene. 

Your healthcare provider will use lab tests to monitor you while you are taking toremifene. 

You should have a pelvic exam (female exam) prior to starting and regularly while taking toremifene.

What should I tell my healthcare provider before using toremifene?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if toremifene is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Congestive heart failure
  • Liver problems
  • Bone metastases
  • Low platelet levels (thrombocytopenia)
  • Low levels of white blood cells (leukopenia)
  • Blood clots

Other Medicines and Supplements. Toremifene may interact with other medicines and supplements. Before taking toremifene, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. People who can become pregnant are usually not prescribed toremifene. Toremifene may cause harm to an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. 

Breastfeeding. It is not known if toremifene passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should stop breastfeeding or stop toremifene.

Interactions

Does toremifene interact with foods or drinks?

Do not eat grapefruit or drink grapefruit juice. Grapefruit may increase the amount of this medicine in your body.

It is unknown if drinking alcohol will affect toremifene. The risk of hot flashes may be increased if you drink alcohol while taking toremifene because alcohol can trigger hot flashes. 

Does toremifene interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking toremifene.

  • A thiazide diuretic, such as hydrochlorothiazide, chlorthalidone, or indapamide, which is a medicine commonly used to lower blood pressure 
  • Warfarin, which is a blood thinner
  • Any medicine for seizures, such as carbamazepine, phenytoin, or phenobarbital
  • Dexamethasone, which is a medicine for certain inflammatory conditions
  • Medicines that can cause QT prolongation, which is a potentially dangerous heart rhythm problem, such as thioridazine, haloperidol, venlafaxine, or amitriptyline
  • Quinidine, procainamide, disopyramide, amiodarone (Pacerone and others), sotalol, ibutilide (Corvert), or dofetilide (Tikosyn), which is a medicine used to control your heart rate or rhythm (antiarrhythmic)
  • Clarithromycin, erythromycin (Ery-Tab and others), levofloxacin, or ofloxacin, which is a medicine used for bacterial infections
  • Ondansetron or granisetron (Sancuso, Sustol), which is a medicine used to help control nausea and vomiting
  • Rifampin, which is a medicine commonly used to treat an infection called tuberculosis
  • Rifabutin (Mycobutin), which is a medicine used to prevent Mycobacterium avium complex infection
  • Ketoconazole, itraconazole (Sporanox, Tolsura), or voriconazole (Vfend), which is a medicine used for fungal infections
  • Nefazodone (Serzone), which is a medicine commonly used for depression
  • A protease inhibitor, such as ritonavir (Norvir), atazanavir (Reyataz), or nelfinavir (Viracept), which is a medicine commonly used to treat HIV
  • St. John’s wort, which is a supplement that may be used to treat depression

Many other medicines may alter the blood levels of toremifene, and vice versa. Tell your healthcare provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with toremifene. Always check with your healthcare provider.

Does Toremifene (Fareston) interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much toremifene?

If you or someone else has used too much toremifene, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of toremifene?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses. 

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