Drug side effects
anastrozole Side Effects
The reactions most often reported to the FDA for anastrozole (also sold as Arimidex), with demographics, serious outcomes, and reporting trends.
Data updated 2026-05-15
- 35,161
- FAERS reports
Data from the FDA Adverse Event Reporting System (FAERS), 2003 to 2025. A FAERS report records a temporal association, not proof of cause. See our methodology for how figures are compiled and de-duplicated.
The most commonly reported side effects of anastrozole come from 35,161 reports to the FDA, broken down here by frequency, patient demographics, and serious outcomes.
This page analyzes 35,161 reports to the FDA Adverse Event Reporting System (FAERS) for anastrozole (Arimidex): the reactions reported most often, who reported them, serious outcomes such as hospitalization, and year-over-year trends. A FAERS report does not prove the drug caused the effect, and report volume tracks how widely a drug is used, not how likely an effect is for any one person. Educational information, not medical advice.
Total Reports
35,161
Reports Mentioning Death
2,383
6.8% of reports — not proof the medicine caused the death
Hospitalizations
7,649
21.8% of reports
Top Indication
Breast Cancer
Most Reported Adverse Reactions
Who Reports Side Effects
Gender Distribution
Age Distribution
Reporting Trend by Year
Reactions in Death Reports
Top reactions reported in 2,383 reports where death was an outcome. These are voluntarily reported and do not establish causation.
| Reaction | Reports |
|---|---|
| DEATH | 926 |
| DIARRHOEA | 347 |
| FATIGUE | 344 |
| DYSPNOEA | 333 |
| NAUSEA | 332 |
| VOMITING | 304 |
| ASCITES | 299 |
| FALL | 288 |
| ASTHENIA | 272 |
| ARTHRALGIA | 269 |
| DECREASED APPETITE | 269 |
| SEPSIS | 264 |
| HEADACHE | 257 |
| COUGH | 249 |
| DIZZINESS | 249 |
| ABDOMINAL PAIN | 247 |
| PRURITUS | 244 |
| CARDIO-RESPIRATORY ARREST | 243 |
| HAEMORRHAGIC STROKE | 241 |
| TACHYCARDIA | 241 |
Reactions in Hospitalization Reports
Top reactions in 7,649 reports where hospitalization was an outcome.
| Reaction | Reports |
|---|---|
| NAUSEA | 703 |
| FATIGUE | 673 |
| DIARRHOEA | 633 |
| DYSPNOEA | 558 |
| VOMITING | 438 |
| ASTHENIA | 436 |
| FALL | 432 |
| ARTHRALGIA | 425 |
| PNEUMONIA | 417 |
| HEADACHE | 387 |
| PAIN | 383 |
| DIZZINESS | 372 |
| MALAISE | 353 |
| PYREXIA | 351 |
| ANAEMIA | 334 |
| WEIGHT DECREASED | 299 |
| DECREASED APPETITE | 272 |
| COUGH | 269 |
| HYPERTENSION | 260 |
Nearby, Related Medications
What the FAERS Data Reveals About anastrozole Side Effects
The FDA Adverse Event Reporting System (FAERS) contains 35,161 voluntary reports linked to anastrozole and its brand equivalents (Arimidex), spanning 2003 through 2025. Of those, 2,383 (6.8%) listed death as an outcome and 7,649 (21.8%) involved hospitalization. The most common indication reported alongside adverse events was Breast Cancer.
Demographic breakdowns help contextualize who is being exposed to the drug. Of reports with known sex, 95% were female and 5% male; age distribution skews toward 45-64, with 9,987 reports in that bracket. The single most reported reaction is fatigue with 3,256 submissions, followed by arthralgia and nausea.
How to read these numbers
FAERS is a signal-detection tool, not a scorecard. Reports are voluntary, and a single case may list multiple suspect drugs, so numbers above should not be read as incidence rates or per-patient risk. Widely prescribed drugs naturally accumulate more reports than niche therapies even when individual risk is low. These aggregates are useful for spotting patterns that merit further pharmacovigilance, not for choosing between medications. This page is for educational reference only and is not medical advice, speak with a licensed clinician about any side-effect concerns.
Drugs With a Similar FAERS Report Volume
Other medications with a total FDA adverse-event report count closest to anastrozole's 35,161.
Read our methodology - how this data is sourced, computed, and verified.