Letrozole (Femara®)

Warning: Letrozole can lead to serious adverse reactions in certain group of patients. Women who have not gone through menopause should not take this medication. Letrozole should be used cautiously in people with liver disease and osteoporosis. To reduce the chances of complications, drug interactions, you should always consult your doctor before taking this or any medication. Do not stop, start, or change the dosage of any medication before consulting with your doctor first.

Indication: This treatment is used to treat breast cancer (e.g. hormone receptor-positive breast cancer) of women after menopause. It also aids in stopping the cancer from returning. Estrogen is a hormone that women produce. Cancer grows and multiplies through estrogen. This medication works by slowing or stopping the production of estrogen the body produces, which helps stop the growth of cancer.

This drug is not usually prescribed to women that are of child bearing age. Letrozole can also be prescribed for other medical conditions not mentioned in this article; talk to your doctor or pharmacist for more information.

Dosage: Letrozole comes as a pill to be taken by mouth. Read the entire Patient information leaflet provided by your pharmacist and safety warnings before using or refilling Letrozole. Talk to your pharmacist about all questions.

This drug is usually taken by mouth once daily, with or without food or as prescribed by your doctor. The dose your doctor prescribes you depends on your response to therapy and medical condition. You should use this medication regularly each day to receive the most benefits from it.

Pregnant women should not handle this medication, as it can be inhaled through the lungs and absorbed through the skin.

Storage: store Letrozole at room temperature (15-25 ° C), away from heat above 40 ° C, light and moisture. Keep the medication out of the reach of children.  Letrozole and all other medications should not be used beyond the expiration date printed on the container.

Overdose: as with any drug, Letrozole overdose may be dangerous, mainly if taken for long term. An overdose of Letrozole can damage the bone marrow, and lead to a life threatening decrease in white blood cells and/or in platelets. If you take an overdose, contact your doctor or the poison control center nearest you to reduce or prevent complications.

Missing dose: always take Letrozole as prescribed.  In case you forget to take a dose, take the missed one as soon as you remember it. However, if it is almost time for your next dose, do not double the next dose to recover the missing, it can be dangerous. Contact your doctor or wait to go back to your regular schedule. This applies not only to Letrozole but also any other drug.

Contraindications: Tell your doctor and pharmacist of all allergies you know of, as you may be allergic to some ingredients in this drug.

Before using this medication, tell your doctor and pharmacist of your medical history, including cholesterol (high blood fats), bone problems (e.g. osteopenia, osteoporosis), stroke or blood clots, heart disease (such as chest pain, heart attack, and heart failure, kidney problems, high blood pressure and liver problems.

Tell all doctors all of medicines you are taking before having surgery, including herbal products and nonprescription drugs.

You should not use this medication while you are pregnant, as it can cause harm to an unborn baby. IT is not known if Letrozole passes through breast milk, but it is not recommended.

This drug may make you dizzy, have blurred vision and make you very tired. Do not do anything that requires alertness, such as driving, operating machinery or eating. Limit your alcohol intake as it will make these symptoms worse.

Mechanism of action (MOA): Letrozole works by reducing the production of estrogens by blocking aromatase, an enzyme involved in their biosynthesis. The cells of breast cancer are hormone-dependent; they need estrogens to multiply. The reduction of estrogen production can thus limit the proliferation of cancer cells and prevents the tumor from growing or developing.

Interactions: There may be some herbs and other medications that may interact with this medication. Tell your doctor of all medications you are taking.

There are certain products and medications that are known to interfere with this drug, such as estrogens (ethinyl estradiol, conjugated estrogens), and estrogen blockers (e.g. anastrozole, tamoxifen).

Side effects: Letrozole tends to cause these adverse effects in most patients:

  • depression and/or anxiety
  • rash or itching
  • pain or upset stomach
  • unusual tiredness
  • fatigue
  • weight gain
  • skin redness, warmth in the face and neck
  • Sweating (hot flushes).

If the side effects above persist for weeks, contact your oncologist. In addition, contact your doctor if you experience any of these symptoms:

  • Persistent constipation
  • confusion
  • severe depression symptoms
  • chest pain
  • difficulty breathing
  • Persistent cough.


1 – santecheznous.com, Quels sont les effets secondaires possibles de ce médicament ?

2 – nlm.nih.gov, Side effects : Letrexole

3 – http://medical-dictionary.thefreedictionary.com/letrozole

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