letrozole
Letrozole (Femara) is an aromatase inhibitor, a type of hormonal therapy. It’s FDA-approved to treat or prevent breast cancer in females who’ve already gone through menopause. It’s sometimes prescribed off-label by fertility specialists to help females become pregnant. Letrozole (Femara) is taken by mouth, typically once a day for breast cancer. Common side effects include hot flashes and pain in the bones, muscles, and joints.
What is Letrozole (Femara)?
What is Letrozole (Femara) used for?
Breast cancer in females who have already gone through menopause:
Preventing breast cancer from coming back (hormone receptor-positive early breast cancer), sometimes after treatment with tamoxifen (Nolvadex)
Treatment of advanced or metastatic breast cancer
How Letrozole (Femara) works
Certain types of breast cancer cells grow when there is estrogen present. Aromatase is a protein in the body involved in making estrogen.
Letrozole (Femara) is an aromatase inhibitor that works by blocking aromatase. In doing so, letrozole (Femara) prevents breast cancer cells from getting the estrogen that’s fuel for the cancer to grow and spread.
Drug Facts
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What are the side effects of Letrozole (Femara)?
Common Side Effects
- High blood cholesterol levels (52%)
- Hot flashes (34%)
- Muscle, bone, or joint pain (25%)
Other Side Effects
- Bone fractures
- Night sweats
- Weight gain
- Nausea
Source: DailyMed
More on Letrozole (Femara) side effects
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Less common
Bone fracture
breast pain
chills, fever, or flu-like symptoms
mental depression
swelling of the feet or lower legs
Rare
Continuing or severe nervousness
dizziness or lightheadedness
fainting
fast heartbeat
increased sweating
pain in the chest, groin, or legs, especially the calves
severe and sudden, unexplained troubled breathing
severe, sudden headache
slurred speech
sudden loss of coordination
sudden, severe weakness or numbness in the arm or leg
swollen glands
vaginal bleeding
vision changes
Incidence not known
Black, tarry stools
blindness
blurred vision
burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
chest discomfort
dark urine
decreased vision
dilated neck veins
extreme tiredness or weakness
general tiredness or weakness
increased need to urinate
irregular breathing
irregular heartbeat
light-colored stools
painful or difficult urination
passing urine more often
sores, ulcers, or white spots on the lips or in the mouth
unusual bleeding or bruising
unusual tiredness or weakness
upper right abdominal pain
white or brownish vaginal discharge
yellow eyes and skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common
confusion
headache
increased thirst
loss of appetite or weight loss
metallic taste
skin rash or itching
sleepiness
spinning or whirling sensation causing loss of balance
stomach pain or upset
trouble sleeping
vomiting
weakness
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Letrozole (Femara)
Pros
Can be used during early and advanced stages of breast cancer
Taken by mouth once daily
Available as a lower-cost generic
Cons
Only for females who've reached menopause (for treating breast cancer)
Can cause menopausal symptoms, such as hot flashes and night sweats
Can weaken your bones if taken long-term
Pharmacist tips for Letrozole (Femara)
Take letrozole (Femara) dose around the same time each day, with or without a meal.
Letrozole (Femara) can cause fatigue, dizziness, and sleepiness. Do not drive or operate machinery until you know how the medication affects you.
Letrozole (Femara) can cause side effects similar to menopausal symptoms, like hot flashes, night sweats, and headaches. Try to avoid alcohol, caffeine, or smoking, because they can worsen these symptoms.
Letrozole (Femara) can raise cholesterol levels in the blood. If your cholesterol gets too high, it can lead to serious heart disease. Your oncologist might routinely check your cholesterol levels to make sure that they're within safe range.
Frequently asked questions about Letrozole (Femara)
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What are the risks and warnings for Letrozole (Femara)?
Letrozole (Femara) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Weakened bones
- Risk factors: Ages 65 years and older
Taking letrozole (Femara) for longer periods of time (2 years or longer) can lower bone mineral density (BMD), raising the risk for fractures. This risk is higher if you take letrozole (Femara) or other medications that can lower BMD for a long time, or if you have other factors that raise your risk for brittle bones (osteoporosis). Before starting treatment, your provider will likely have you do a scan to check on your bones, and repeat those scans every couple years during treatment. They might also recommend medications to prevent bone loss, such as zoledronic acid (Zometa) or denosumab (Xgeva).
High cholesterol levels
One of the more common side effects of letrozole (Femara) is higher levels of cholesterol in the blood. Over time, this can raise the risk for heart attacks and strokes. To lower this risk, your oncology care team will help you plan nutritious meals and exercise routines that you can do regularly. Your oncologist will check on your cholesterol levels before you start letrozole (Femara) and periodically during treatment. If they notice your cholesterol levels rising, they might have you start medications to lower your cholesterol levels.
Liver problems
Risk factors: Severe liver disease and liver dysfunction
The liver is responsible for breaking down letrozole (Femara) in your body. If there is a problem with your liver, it can lead to high levels of letrozole (Femara) in your body and raise your risk of side effects. Let your oncology care team know if you have an existing liver problem, because your oncologist might have to lower your dose of letrozole (Femara).
Risk of drowsiness
Letrozole (Femara) can cause sleepiness, which can lower your ability to think, react, and focus. Your risk might be higher if you're taking other medications that can cause you to feel sleepy (e.g., benzodiazepines, muscle relaxants, sleep medications). Make sure you know how this medication affects you before driving a car or doing activities that require your concentration. Talk to your healthcare provider right away if you feel too sleepy from taking letrozole (Femara).
Harm to unborn baby
It's unlikely that pregnancy can happen after menopause, but if you think you could be pregnant, let your oncology care team know. Letrozole (Femara) can cause harm to an unborn baby. If there's a chance that you still have the ability to get pregnant, use an effective birth control while taking letrozole (Femara) and for at least 3 weeks after your last dose.
Letrozole (Femara) dosage forms
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 2.5mg | 10 tablets | $8.82 | $0.88 |
Typical dosing for Letrozole (Femara)
The typical dose is 2.5 mg by mouth daily. Your oncology care team will determine how long your treatment should last.
Your oncologist might lower your dose if you have a history of liver problems.
Interactions between Letrozole (Femara) and other drugs
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Ceritinib
- Cilostazol
- Clarithromycin
- Tegafur
How much does Letrozole (Femara) cost?
What are alternatives to Letrozole (Femara)?
Breast cancer in females who have already gone through menopause:
Preventing breast cancer from coming back (hormone receptor-positive early breast cancer), sometimes after treatment with tamoxifen (Nolvadex)
Treatment of advanced or metastatic breast cancer
Early stage HR+ breast cancer in postmenopausal women
Advanced or metastatic HR+ breast cancer in postmenopausal women
Advanced breast cancer in postmenopausal women that's getting worse after treatment with tamoxifen
Early breast cancer in postmenopausal women who've had 2 to 3 years of treatment with tamoxifen
Advanced breast cancer in postmenopausal women whose cancer has worsened following treatment with tamoxifen
What is the latest news about Letrozole (Femara)?
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References
Best studies we foundAccord Healthcare, Inc. (2024). Letrozole tablet, film coated [package insert]. DailyMed.
American Cancer Society. (n.d.). Hair loss.
American Cancer Society. (2024). Hormone therapy for breast cancer.
American College of Obstetricians and Gynecologists. (2018). ACOG Committee Opinion No. 738 summary: Aromatase inhibitors in gynecologic practice. Obstetrics and Gynecology.
Chan, H. J., et al. (2016). Structural and functional characterization of aromatase, estrogen receptor, and their genes in endocrine-responsive and -resistant breast cancer cells. The Journal of Steroid Biochemistry and Molecular Biology.
Henry, N. L., et al. (2012). Predictors of aromatase inhibitor discontinuation as a result of treatment-emergent symptoms in early-stage breast cancer. Journal of Clinical Oncology.
Karatas, F., et al. (2016). Management of hair loss associated with endocrine therapy in patients with breast cancer: An overview. SpringerPlus.
National Cancer Institute. (n.d.). Advanced cancer.
National Cancer Institute. (n.d.). Metastatic.
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