Letrozole is a prescription drug that treats estrogen-receptive breast cancer. As an aromatase inhibitor, it prevents the body from making estrogen, stopping the growth of the cancer. Doctors use it along with anticancer drugs to treat cancer, but women may take letrozole for several years after the cancer has cleared up to prevent recurrence.
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Femara
Letrozole
Treats estrogen-receptive breast cancer.
Endocrine-metabolic agent, antineoplastic agent
Tablet
By mouth
Letrozole treats and prevents estrogen-receptive breast cancer by lowering the body’s estrogen levels. Doctors use it to treat early breast cancer and advanced or metastatic breast cancer.
Tablet
2.5 mg
For estrogen-receptive breast cancer: 2.5 mg tablet taken once daily
Letrozole
2.5mg tablet
Your healthcare provider will tell you how much medicine to use. Do not use more than directed.
The clinic or prescribing healthcare provider will most likely give you a sheet of instructions for taking letrozole. Please read and follow these instructions.
Take only one dose daily.
Doses can be taken with or without food.
Swallow the tablet whole with a drink of water.
Store letrozole tablets in a closed container at room temperature.
If a dose is missed, take it when remembered unless it is nearly time for the next dose.
The clinic or prescriber will usually give you a sheet of instructions for taking this medicine. It may give you a precise time period defining when you can take a missed dose. Follow these instructions.
Instructions for taking a missed dose may vary by clinic or practitioner.
If there is no instruction sheet, ask the prescriber about managing missed doses.
Do not take a double dose to make up for a missed dose.
This medicine is not right for everyone.
Do not use it if you are pregnant or have had an allergic reaction to letrozole.
It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Immediately inform the prescriber if you become pregnant.
Use an effective form of birth control during treatment with this medicine and for at least three weeks after the last dose.
Do not breastfeed while you are taking this medicine and for at least three weeks after your last dose.
Tell any doctor or other healthcare provider who treats you that you are using this medicine.
The prescriber will need regular visits and blood tests to monitor treatment progress and the adverse effects of this medicine. Keep all appointments.
Before starting letrozole, tell the prescriber if you are pregnant, breastfeeding, or if you have:
Liver problems
High cholesterol
Osteoporosis or other bone problems
Letrozole will cause side effects in nearly all women who take it.
Before receiving this medicine, make sure you understand all the risks and benefits.
Work closely with your doctor during your treatment.
The most common reason women stop aromatase inhibitor therapy is joint pain. Ask the healthcare team how to manage and minimize the risk of joint pain.
Letrozole can cause serious problems including:
High cholesterol (in about half of patients)
Joint pain (over 10% of patients)
Bone fractures (10% of patients)
Osteoporosis
Liver problems
Blood clot problems including stroke
Heart problems including heart attack
New cancers
This medicine may make you dizzy, sleepy, or tired. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
This medicine can impair fertility.
Letrozole has very few significant drug interactions. Some are serious, so make sure the prescriber knows about all the drugs and supplements regularly being taken, particularly:
Estrogens
Tamoxifen
DHEA dietary supplements
Tell all other healthcare professionals treating you about letrozole before they prescribe new medications.
Serious side effects
Talk to a healthcare provider if you notice any signs or symptoms of a possible serious side effect including:
Severe or chronic bone or joint pain
Bone fracture
Dark urine, pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
Excessive swelling of the feet, lower legs, or hands
Pain in the lower leg
Numbness or weakness on one side of your body, sudden or severe headache, problems with vision, speech, or walking
Chest pain, trouble breathing
Unexplained or significant weight gain
Vaginal discharge, bleeding, or discomfort
Allergic reaction: Skin rash, itching, swelling in your face, mouth, or throat, difficulty breathing
Less serious side effects
Hot flashes
Night sweats
Muscle or joint pain
Weight gain
Nausea
Fatigue
Headache
Swelling of the hands, feet, or ankles
Feeling tired or exhausted
Find more information about letrozole side effects here.
Femara drug summary, Prescriber’s Digital Reference (PDR)
Femara letrozole tablet prescribing information, DailyMed (NIH National Library of Medicine)
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