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anastrozole Side Effects

Also known as: Arimidex

Analysis of 35,161 adverse event reports submitted to the FDA from 2003 to 2025.

Total Reports

35,161

Death-Related

2,383

6.8% of reports

Hospitalizations

7,649

21.8% of reports

Top Indication

Breast Cancer

Most Reported Adverse Reactions

FATIGUE
3,256
ARTHRALGIA
3,158
NAUSEA
2,648
ALOPECIA
2,537
DIARRHOEA
2,267
PAIN
1,773
HEADACHE
1,741
ASTHENIA
1,569
DYSPNOEA
1,530
DIZZINESS
1,468
HOT FLUSH
1,402
PAIN IN EXTREMITY
1,368
MALIGNANT NEOPLASM PROGRESSION
1,313
MALAISE
1,278
VOMITING
1,270
INSOMNIA
1,262
OFF LABEL USE
1,173
DRUG INEFFECTIVE
1,169
FALL
1,138
COUGH
1,121

Who Reports Side Effects

Gender Distribution

Female 31,192 (95%)
Male 1,575 (5%)
Unknown 136

Age Distribution

0-17 290 (1%)
18-44 1,241 (5%)
45-64 9,987 (43%)
65-74 6,854 (29%)
75+ 5,112 (22%)

Reporting Trend by Year

2003 2025

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
OFF LABEL USE 290
DECREASED APPETITE 272
COUGH 269
HYPERTENSION 260

Nearby — Related Medications

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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.

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.