Letrozole
Letrozole is used to treat breast cancer in postmenopausal women. It is available as Femara and is commonly prescribed in the oncology category.
About Letrozole
Letrozole is a non-steroidal aromatase inhibitor (third generation) also known by the brand name Femara. It is primarily used to letrozole is prescribed to treat: • Breast cancer in postmenopausal women • Various related conditions in the oncology category • Associated symptoms and complications It is an important medication that helps manage these conditions effectively. Letrozole is available in oral tablet (2.5 mg) form. Healthcare providers commonly prescribe Letrozole for conditions including Attention Deficit Hyperactivity Disorder (ADHD), Lupus Anticoagulant, and Vertigo.
Letrozole at a Glance
- Brand names
- Femara
- Drug class
- Non-Steroidal Aromatase Inhibitor (Third Generation)
- Pregnancy category
- FDA Category Category X (when used for breast cancer in postmenopausal women, pregnancy is not expected) — Letrozole is contraindicated in women who are or could become pregnant. Animal studies show embryo-fetal toxicity, including teratogenicity. When used off-label for ovulation induction in premenopausal women, its short half-life means exposure is minimized before conception, but pregnancy after the dosing window is the goal — pregnancy during active dosing must be avoided.
- Available forms
- Oral tablet (2.5 mg)
- Therapeutic categories
- Oncology, Aromatase Inhibitors, Breast Cancer
- Conditions treated
- 3 related conditions on this site
What Letrozole Is Used For
Letrozole is prescribed to treat:
• Breast cancer in postmenopausal women • Various related conditions in the oncology category • Associated symptoms and complications
It is an important medication that helps manage these conditions effectively.
Dosage Quick Reference
These are general dosage guidelines for Letrozole. Your doctor will determine the appropriate dose for your specific situation.
| Condition | Starting Dose | Maintenance Dose |
|---|---|---|
| Adjuvant treatment of HR-positive early breast cancer (postmenopausal) | 2.5 mg once daily | 2.5 mg once daily for 5 years (extended adjuvant therapy may continue up to 10 years total) |
| Extended adjuvant therapy (after 5 years of tamoxifen) | 2.5 mg once daily | 2.5 mg once daily for an additional 5 years |
| First-line treatment of advanced HR-positive breast cancer | 2.5 mg once daily | Continue until disease progression or unacceptable toxicity |
| Ovulation induction (off-label, premenopausal) | 2.5 mg once daily on cycle days 3–7 | May increase to 5 mg or 7.5 mg in subsequent cycles if no ovulation |
| Severe hepatic impairment | 2.5 mg every other day | Adjust based on tolerability |
Side Effects
Common side effects may include:
• Nausea or stomach upset • Headache • Dizziness or lightheadedness • Fatigue or tiredness • Mild rash or itching
Serious side effects (seek immediate medical attention):
• Severe allergic reactions (rash, hives, swelling, difficulty breathing) • Unusual bleeding or bruising • Severe stomach pain • Signs of liver problems (yellowing of skin/eyes, dark urine) • Chest pain or irregular heartbeat • Severe dizziness or fainting • Signs of serious adverse effects
See also: Drug Interactions ↓
Drug Interactions
Letrozole is metabolized primarily by CYP3A4 and CYP2A6. Its interaction profile reflects these pathways and its profound estrogen-suppressing effect.
- Tamoxifen and other estrogen-modulating agents: Concurrent use with tamoxifen reduces letrozole plasma levels by approximately 38 percent and is not recommended. These agents are typically used sequentially, not together, in adjuvant breast cancer therapy.
- Estrogen-containing therapies (e.g., oral contraceptives, hormone replacement therapy, vaginal estrogens): Antagonize the therapeutic effect of letrozole. Avoid concurrent estrogen exposure unless specifically directed for non-cancer indications.
- Strong CYP3A4 inducers (e.g., rifampin, phenytoin, carbamazepine, St. John wort): May reduce letrozole exposure and efficacy. Avoid combination when possible; consider an alternative aromatase inhibitor or monitor disease response carefully.
- CYP2A6 substrates (e.g., nicotine, certain coumarins): Letrozole can modestly alter metabolism of these agents. Clinical significance is usually limited but worth noting in heavy smokers initiating therapy.
- Bisphosphonates (e.g., alendronate, zoledronic acid): Not a true interaction, but commonly co-prescribed because letrozole-induced estrogen suppression accelerates bone loss. Bone density should be monitored and treatment offered as indicated.
See also: Questions to Ask Your Doctor ↓
Key Considerations
Known drug interactions
Letrozole has documented interactions with other medications, supplements, and certain foods. Review the Drug Interactions section below and tell your healthcare provider about every medication you take, including over-the-counter products. Jump to section →
Additional Information
What is Letrozole?
Letrozole (generic name: Letrozole) is a medication primarily used to treat breast cancer in postmenopausal women. It is marketed under the brand name(s) Femara and belongs to the Oncology category of medications.
How Does Letrozole Work?
Letrozole works through several mechanisms to provide therapeutic benefits:
- Acts on specific receptors or pathways in the body
- Modulates biological processes related to the treated condition
- Provides symptom relief and improves quality of life
- Helps manage the underlying condition effectively
- Works best when combined with appropriate lifestyle modifications
The medication is designed to target the specific pathways involved in breast cancer in postmenopausal women, making it an effective treatment option.
Common Uses
Primary Indications
Letrozole is commonly prescribed for:
- Breast cancer in postmenopausal women: The main indication for this medication
- Related Conditions: Associated symptoms and complications
- Prevention: May help prevent progression of certain conditions
- Symptom Management: Reduces discomfort and improves daily function
Additional Uses
In some cases, Letrozole may also be prescribed for:
- Off-label uses as determined by your healthcare provider
- Combination therapy with other medications
- Long-term management of chronic conditions
- Short-term treatment of acute symptoms
Dosage and Administration
Letrozole dosing varies based on the specific condition being treated and individual patient factors.
Typical Dosing:
- Starting dose is typically determined by your healthcare provider
- May be adjusted based on response and tolerability
- Can be taken with or without food (follow specific instructions)
- Usually taken once or twice daily
Administration Tips:
- Take at the same time(s) each day for best results
- Swallow tablets/capsules whole unless instructed otherwise
- Don't skip doses
- Complete full course of treatment as prescribed
- Follow your doctor's specific instructions carefully
Important Safety Information
Who Should Not Take Letrozole?
Do not take Letrozole if you:
- Are allergic to Letrozole or any ingredients
- Have certain medical conditions (discuss with your doctor)
- Are taking medications that interact with Letrozole
- Have severe liver or kidney disease (without dose adjustment)
Drug Interactions
Inform your doctor about all medications you take, including:
- Prescription medications
- Over-the-counter drugs
- Vitamins and supplements
- Herbal products
Some medications may interact with Letrozole, affecting its efficacy or increasing side effect risk.
Pregnancy and Breastfeeding
Pregnancy:
- Discuss risks and benefits with your doctor if pregnant or planning pregnancy
- May require special monitoring or dose adjustments
- Some medications should be avoided during pregnancy
Breastfeeding:
- Consult your doctor about safety while breastfeeding
- May pass into breast milk
- Benefits and risks should be carefully considered
Monitoring and Follow-Up
While taking Letrozole, your doctor may monitor:
- Effectiveness of treatment (symptom improvement)
- Side effects or adverse reactions
- Laboratory values if applicable
- Blood pressure, heart rate, or other vital signs as appropriate
- Overall response to therapy
Regular follow-up appointments are important to ensure the medication is working properly and to make any necessary adjustments.
Managing Side Effects
Most side effects are mild and improve with time. Here are strategies for common side effects:
Gastrointestinal Upset
- Take with food if allowed
- Stay well hydrated
- Eat smaller, more frequent meals
- Report persistent nausea or vomiting
Dizziness
- Rise slowly from sitting or lying positions
- Avoid sudden movements
- Stay hydrated
- Avoid alcohol
- Report severe or persistent dizziness
Fatigue
- Get adequate rest
- Maintain regular sleep schedule
- Exercise as tolerated
- Report excessive tiredness that interferes with daily activities
Lifestyle Considerations
To maximize the benefits of Letrozole:
- Follow a healthy, balanced diet
- Exercise regularly as recommended by your doctor
- Maintain a healthy weight
- Avoid alcohol or limit consumption
- Don't smoke
- Manage stress through relaxation techniques
- Get adequate sleep
- Stay well hydrated
- Keep all follow-up appointments
- Take medication consistently as prescribed
When to Contact Your Doctor
Seek immediate medical attention if you experience:
- Signs of severe allergic reaction (difficulty breathing, severe rash, swelling)
- Chest pain or rapid heartbeat
- Severe dizziness or fainting
- Unusual bleeding or bruising
- Signs of liver problems (yellowing of skin/eyes, dark urine, severe fatigue)
- Severe stomach pain
- Any symptoms that concern you
Contact your doctor for non-emergency issues:
- Mild to moderate side effects that persist
- Questions about your medication
- Concerns about effectiveness
- New medications prescribed by another doctor
- Scheduled surgery or dental procedures
- Planning pregnancy
Storage
Store Letrozole at room temperature (68-77°F or 20-25°C) away from light, heat, and moisture. Keep in original container. Keep out of reach of children and pets. Do not use past expiration date.
Important Reminders
- Take exactly as prescribed by your doctor
- Don't stop suddenly without medical advice
- Keep all follow-up appointments
- Report any unusual symptoms
- Don't share medication with others
- Store safely away from children
- Check expiration dates
- Ask your pharmacist if you have questions
Clinical Benefits
When used appropriately, Letrozole provides several benefits:
- Effective management of breast cancer in postmenopausal women
- Improvement in quality of life
- Reduction in symptoms
- Prevention of complications
- Generally well-tolerated when used as directed
- Backed by clinical research and extensive use
Disclaimer: This information is for educational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Always consult your physician or other qualified healthcare provider with any questions about a medical condition or medication.
Frequently Asked Questions
Questions to Ask Your Doctor About Letrozole
Consider discussing these topics at your next appointment:
- How was the decision made between letrozole, anastrozole, exemestane, or tamoxifen for my situation?
- How often will my bone density and cholesterol be monitored?
- What can we do about joint pain or hot flashes if they become difficult to tolerate?
- When and how will we decide whether to extend letrozole beyond 5 years?
- Are there lifestyle changes — exercise, diet, weight management — that improve outcomes alongside letrozole?
Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.