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Cancer Treatment Centers of America

Letrozole (Femara®)


Brand Name: Femara®

Letrozole is used in the treatment of breast cancer in women who have experienced menopause.

Letrozole belongs to a class of drugs known as nonsteroidal aromatase inhibitors. Letrozole decreases the amount of estrogen in the body. Because many types of breast cancer cells require estrogen to grow, this drug may slow or stop the growth of cancer cells.

Letrozole is given as a tablet taken by mouth. Usually, this medication is taken once daily with or without food. It’s best to take letrozole at around the same time each day. This medication may be taken for several years or longer; your doctor will recommend the exact duration.

Letrozole side effects

To prevent problematic interactions between letrozole and other drugs, be sure to tell your doctor if you are allergic to any medications, and what other medications and supplements you are currently taking. You should also inform your doctor if you have or ever had a liver tumor, liver or disease, osteoporosis, if you are pregnant or planning to become pregnant, or if you are breastfeeding. Letrozole may cause drowsiness, so be sure to not drive a car or operate machinery until you are familiar with how the medication affects your body.

Possible side effects may include:

  • Hot flushes
  • Night sweats
  • Nausea
  • Vomiting
  • Muscle, joint, or bone pain
  • Excessive tiredness
  • Headache
  • Dizziness
  • Excessive tiredness
  • Swelling of the hands, feet, ankles, or lower legs
  • Appetite loss
  • Constipation
  • Diarrhea
  • Stomach pain
  • Difficulty sleeping
  • Vaginal bleeding or irritation
  • Breast pain
  • Flu-like symptoms
  • Difficulty urinating
  • Chest pain
  • Rash

Some of letrozole’s side effects can be serious. Call your doctor immediately if you experience any of these symptoms:

  • Chest pain
  • Difficulty breathing

Please note that this is not a comprehensive list. Patients may experience additional effects not mentioned above.

At Cancer Treatment Centers of America (CTCA), your team of cancer experts will explain each of the side effects of letrozole with you in detail, as well as the side effects and expectations of all other medications planned as part of your individualized treatment plan.

Letrozole for cancer treatment

Letrozole is approved by the FDA for the following cancer treatments:

  • Breast cancer that has spread within the breast or to other areas of the body
  • Breast cancer in women who have already been treated with surgery, radiation, and/or chemotherapy. Letrozole may be used immediately after these treatments (adjuvant therapy), or may be given after 5 years of treatment with tamoxifen. In this case, letrozole is used to kill any cancer cells that may still remain in the body after the previous treatment

At CTCA, our integrative approach to cancer treatment works to fight your disease on all fronts and ensures that you remain at the center of everything we do. We encourage participation from both you and your family to make certain you are comfortable with all decisions made regarding your treatment.

The information provided here is for educational purposes only. In no way should it be considered as offering medical advice. Cancer Treatment Centers of America assumes no responsibility for how this material is used. Please check with a physician if you suspect you are ill. Also note that while Cancer Treatment Centers of America frequently updates its contents, medical information changes rapidly. Therefore, some information may be out of date.