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Fareston

Generic Name: toremifene (tor EM i feen)
Brand Name: Fareston

Medically reviewed by Drugs.com on Jul 15, 2020 – Written by Cerner Multum

What is Fareston?

Fareston is used in postmenopausal women to treat metastatic breast cancer (cancer that has spread to other parts of the body). Your doctor may test your tumor before prescribing this medicine.

Fareston may also be used for purposes not listed in this medication guide.

Important Information

You should not use Fareston if you have a history of long QT syndrome, or low levels of potassium or magnesium in your blood.

Fareston can cause a life-threatening heart rhythm disorder. Stop using this medicine and call your doctor at once if you have: fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness.

Before taking this medicine

You should not use Fareston if you are allergic to it, or if you have:

  • long QT syndrome; or

  • an uncontrolled electrolyte imbalance (low levels of potassium or magnesium in your blood).

Tell your doctor if you have ever had:

Fareston may increase your risk of developing a condition that can lead to uterine cancer. Talk to your doctor about your individual risk. Report any unusual vaginal bleeding right away.

Fareston is for use only in women who can no longer get pregnant. Fareston can harm an unborn baby. Do not use if you are pregnant. Use effective birth control if you are not past menopause. Tell your doctor if you think you may be pregnant.

Fareston can make hormonal birth control less effective, including birth control pills, injections, implants, skin patches, and vaginal rings. To prevent pregnancy while using this medicine, use a barrier form of birth control: condom, diaphragm, cervical cap, or contraceptive sponge.

You should not breastfeed while using Fareston.

How should I take Fareston?

Your doctor may perform a pelvic exam to make sure you do not have conditions that would prevent you from safely using Fareston.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Take the medicine at the same time each day, with or without food.

You will need frequent medical tests.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include headache, dizziness and nausea.

What should I avoid while taking Fareston?

Grapefruit and grapefruit juice may interact with Fareston and lead to unwanted side effects. Avoid the use of grapefruit products while taking this medicine.

Ask your doctor or pharmacist before taking any over-the-counter medicines, vitamins, or herbal products. Avoid taking an herbal supplement containing St. John's wort.

Fareston 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.

Fareston can cause a life-threatening heart rhythm disorder. Stop using this medicine and call your doctor at once if you have:

  • fast or pounding heartbeats;

  • fluttering in your chest;

  • sudden dizziness (like you might pass out);

  • shortness of breath; or

  • a seizure.

Also call your doctor at once if you have:

  • pelvic pain, abnormal vaginal bleeding;

  • a 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 calcium levels--confusion, tiredness, nausea, vomiting, loss of appetite, constipation, increased thirst or urination, weight loss;

  • liver problems--loss of appetite, stomach pain (upper right side), dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or

  • signs of a blood clot--sudden numbness or weakness (especially on one side of the body), severe headache, slurred speech, problems with vision or balance, chest pain, wheezing, coughing up blood.

Common side effects may include:

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.

What other drugs will affect Fareston?

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Fareston can cause a serious heart problem. Your risk may be higher if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

Many drugs can affect Fareston. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

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.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.