Femaraletrozole
According to the FDA label: Letrozole tablet is an aromatase inhibitor indicated for: Adjuvant treatment of postmenopausal women with hormone receptor positive early breast cancer ( 1.1 ) Extended adjuvant treatment of postmenopausal women with early breast cancer who have received prior standard adjuvant tamoxifen therapy ( 1.2 ) First and second-line treatment of postmenopausal women with hormone receptor positive or unknown advanced breast cancer ( 1.3 ) 1.1 Adjuvant Treatment of Early Breast Cancer Letrozole tablets…
60,074 adverse event reports submitted to the FDA (data available)
Top Reported Adverse Events
The most frequently reported events in association with Femara in the FAERS database. These are events reported by patients taking this medication, not necessarily caused by it. A single report may include multiple events.
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Tap any term below for a plain-language definition.
Fatigue 7,286 reports
Extreme tiredness or lack of energy that does not improve with rest.
Full definition in the glossary → See all drugs reporting this event →Nausea 5,365 reports
The feeling of sickness in your stomach that often comes before vomiting.
Full definition in the glossary → See all drugs reporting this event →Neutropenia 5,007 reports
A low level of neutrophils, a type of white blood cell that fights infection.
Full definition in the glossary →Diarrhoea 4,571 reports
Loose or watery bowel movements, often frequent. Also spelled diarrhea in American English.
Full definition in the glossary → See all drugs reporting this event →Malignant Neoplasm Progression 4,379 reports
A report that a cancer grew or spread. This describes the course of the illness, not necessarily an effect of the drug. Malignant neoplasm is the medical term for a cancerous growth.
Full definition in the glossary →Arthralgia 3,881 reports
White Blood Cell Count Decreased 3,740 reports
A blood test result showing a low level of white blood cells, which help fight infection.
Full definition in the glossary →Alopecia 3,629 reports
Pain 2,993 reports
A general report of physical discomfort, used when no more specific location is given.
Full definition in the glossary →Asthenia 2,920 reports
Physical weakness or lack of strength.
Full definition in the glossary →Dyspnoea 2,888 reports
Shortness of breath or difficulty breathing. Also spelled dyspnea in American English.
Full definition in the glossary → See all drugs reporting this event →Neoplasm Progression 2,795 reports
A report that a tumour grew or advanced. This describes the course of the illness, not necessarily an effect of the drug. Neoplasm is the medical term for a growth or tumour.
Full definition in the glossary →Vomiting 2,727 reports
Throwing up the contents of the stomach.
Full definition in the glossary → See all drugs reporting this event →Death 2,633 reports
A report that the person died. A death appearing in reports for a drug does not mean the drug caused it. Reports record that a death occurred while the medication was being used, which can happen for many unrelated reasons.
Full definition in the glossary →Headache 2,433 reports
Pain in the head or upper neck.
Full definition in the glossary → See all drugs reporting this event →
Ranked by frequency of reports, not severity. The most-reported event is not necessarily the most dangerous or the most common in patients taking this drug.
Who Is Reporting
Demographics of patients in FAERS reports that included this information. Not all reports include patient demographics.
By Sex
View reporter sex data as a table
| Sex | Reports |
|---|---|
| Female | 55,266 |
| Male | 854 |
| Unknown | 71 |
By Age Group
View age group data as a table
| Age group | Reports |
|---|---|
| 0-17 | 354 |
| 18-34 | 921 |
| 35-49 | 5,297 |
| 50-64 | 14,979 |
| 65-74 | 11,592 |
| 75+ | 8,626 |
This shows who filed reports, reflecting who takes this drug and who tends to report, not who is at greatest risk.
Reported Outcomes
Outcomes recorded in FAERS reports that included Femara. A single report may involve multiple reactions, each with a different outcome. These categories are defined by FDA reporting guidelines, not by PillSignal.
View outcome data as a table
| Outcome | Reports |
|---|---|
| Other Serious | 36,249 |
| Hospitalization | 15,375 |
| Non-Serious | 11,682 |
| Death | 5,933 |
| Life-Threatening | 2,089 |
| Disability | 1,371 |
Serious outcomes are far more likely to be reported than mild ones, so this overstates how often outcomes are serious. A recorded death does not mean the drug caused it.
Report Volume Over Time
Number of FAERS reports received per quarter for Femara. Changes in volume may reflect shifts in prescribing rates, media attention, or reporting behavior, not changes in the medication's safety profile.
The steep increase around 2004 reflects the FDA's move to electronic submission, not a change in this drug's safety. Trends track reporting volume, not risk.
Related Drugs
Other medications with similar adverse event profiles in FDA FAERS reports.
Data Source
This data is sourced from the FDA's Adverse Event Monitoring System (AEMS), formerly FAERS, via the OpenFDA API. PillSignal is not affiliated with the FDA.
View this data on the FDA website →Data last updated: June 2026