Letrozole

Your doctor has prescribed letrozole for you. Letrozole comes as a tablet to take by mouth.

This medication is used in women who have experienced menopause (change of life; end of monthly menstrual periods) to:

• treat breast cancer that has spread within the breast or to other areas of the body.

• treat early breast cancer in women who have already been treated with surgery, radiation and/or chemotherapy. Letrozole is sometimes used right after these treatments and sometimes after 5 years of treatment with a medication called tamoxifen (Nolvadex). Letrozole is used to stop any cancer cells that remain after these treatments from spreading.

Letrozole is in a class of medications known as nonsteroidal aromatase inhibitors. It decreases the amount of estrogen produced by the body. This can slow or stop the growth of some breast tumors that need estrogen to grow.

Letrozole is usually taken once a day, with or without food. Try to take letrozole at around the same time every day. Follow the directions on your prescription label carefully and ask your doctor or pharmacist to explain anything you do not understand. Take letrozole exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

You may need to take letrozole for several years or longer. Continue to take letrozole even if you feel well. Do not stop taking letrozole without talking to your doctor.

If you forget to take a dose of letrozole, take the missed dose as soon as you remember it. However, if it is almost time for your next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed dose and do not take more than one dose of letrozole in one day.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Before taking letrozole,

• tell your doctor and pharmacist if you are allergic to letrozole, any other medications, or any of the inactive ingredients in letrozole tablets. Ask your doctor or pharmacist for a list of the inactive ingredients.
• tell your doctor or pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements and herbal products you are taking or plan to take. Be sure to mention any of the following: other medications to treat cancer, medications that contain estrogen such as hormone replacement therapy and hormonal contraceptives (birth control pills, patches, rings, and injections), tamoxifen (Nolvadex), and raloxifene (Evista). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had any medical condition, especially liver disease and osteoporosis (condition in which the bones are weak and break easily).
• you should know that letrozole should only be used by women who have experienced menopause and cannot become pregnant. However, if you are pregnant or breast-feeding, you should tell your doctor before you begin taking this medication. Use a reliable method of birth control to prevent pregnancy during your treatment. Letrozole may harm the fetus.
• you should know that letrozole may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.

Letrozole may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• hot flushes

• night sweats

• nausea

• vomiting

• muscle, joint, or bone pain

• excessive tiredness

• headache

• dizziness

• muscle weakness

• swelling of the hands, feet, ankles, or lower legs

• loss of appetite

• constipation

• diarrhea

• stomach pain

• difficulty falling asleep or staying asleep

• vaginal bleeding or irritation

• breast pain

• flu-like symptoms

• difficulty urinating

• pain on urination

• cough

• rash

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

• chest pain

• difficulty breathing

Letrozole may cause or worsen osteoporosis. Talk to your doctor about the risk of taking this medication and to find out what you can do to decrease this risk.

Letrozole may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.

Keep letrozole in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

• Keep all appointments with your doctor.

• Do not let anyone else take your medication. Ask your pharmacist if you have any questions about refilling your prescription.

Last Reviewed - 04/01/2012