Drug · FAERS side-effect profile with label screen
Anastrozole side effects: what 21,328 FDA adverse event reports show
Who reports
21,328 reports · 74% serious · 1,543 with death outcome · 93% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Anastrozole tablets are an aromatase inhibitor indicated for: Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer ( 1.1 ) First-line treatment of postmenopausal women with hormone receptor-positive or hormone r.
FDA label, Indications and Usage
What it is
Anastrozole Tablets, USP for oral administration contain 1 mg of anastrozole, a non-steroidal aromatase inhibitor. It is chemically described as 1,3-Benzenediacetonitrile, a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1-ylmethyl).
FDA label, Description section
Boxed warning
None in the current label
How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation.
Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)?
That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.
Causality screen of the 40 strongest signals
Labeled (related wording) 3Likely indication confounding 2Lab value / disease marker 8Not in label — unassessed 27
What the badges mean
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 1,150 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Performance enhancing product use | 20 | 265.5 161.9–435.3ROR 265.7 · χ² 3,932 / p <1e-300 | 174.2 EB05 119.1 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=20 · ♀ 0% (drug 93%) · 100% clinician | not reported in cached trials |
| Amaurosis fugax | 222 | 258.0 222.6–298.9ROR 260.7 · χ² 44,677 / p <1e-300 | 200.4 EB05 179.3 · IC025 +6.9 3/3 methods agree | Not in label — unassessed | serious n=222 · 94% clinician | not reported in cached trials |
| Vitreoretinal traction syndrome | 15 | 188.8 108.6–328.2ROR 188.9 · χ² 2,190 / p <1e-300 | 132.0 EB05 84.9 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Pik3ca-activated mutation | 47 | 165.6 121.6–225.6ROR 166.0 · χ² 6,428 / p <1e-300 | 134.0 EB05 104.8 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=47 | not reported in cached trials |
| Pseudocirrhosis | 45 | 156.3 114.1–214.1ROR 156.6 · χ² 5,846 / p <1e-300 | 127.6 EB05 99.2 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious n=45 · 100% clinician | not reported in cached trials |
| Human rhinovirus test positive | 51 | 155.9 116.0–209.5ROR 156.3 · χ² 6,629 / p <1e-300 | 128.1 EB05 101.2 · IC025 +5.4 3/3 methods agree | Lab value / disease marker | serious n=51 | not reported in cached trials |
| Musculoskeletal toxicity | 22 | 133.2 85.3–208.0ROR 133.4 · χ² 2,424 / p <1e-300 | 106.6 EB05 74.2 · IC025 +4.3 3/3 methods agree | Labeled (related wording) related wording | serious n=21 · 100% clinician | not reported in cached trials |
| Carbohydrate antigen 15-3 increased | 77 | 110.5 87.4–139.9ROR 110.9 · χ² 7,405 / p <1e-300 | 97.0 EB05 80.1 · IC025 +5.5 3/3 methods agree | Lab value / disease marker | serious n=76 | not reported in cached trials |
| Pleural neoplasm | 16 | 105.5 63.0–176.7ROR 105.6 · χ² 1,400 / p <1e-300 | 85.8 EB05 56.0 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Viral test positive | 35 | 103.7 73.2–146.9ROR 103.9 · χ² 3,124 / p <1e-300 | 89.4 EB05 67.2 · IC025 +4.8 3/3 methods agree | Lab value / disease marker | serious n=34 · 100% clinician | not reported in cached trials |
| Metastases to breast | 31 | 102.9 71.1–148.9ROR 103.0 · χ² 2,736 / p <1e-300 | 88.2 EB05 65.1 · IC025 +4.6 3/3 methods agree | Not in label — unassessed | serious n=31 | not reported in cached trials |
| Chest wall mass | 22 | 91.1 58.9–141.0ROR 91.2 · χ² 1,711 / p <1e-300 | 77.9 EB05 54.2 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=22 · 100% clinician | not reported in cached trials |
| Metastases to spinal cord | 16 | 88.1 52.8–146.9ROR 88.2 · χ² 1,184 / p 8e-260 | 74.0 EB05 48.3 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Pneumonia haemophilus | 40 | 87.9 63.6–121.5ROR 88.1 · χ² 3,071 / p <1e-300 | 77.8 EB05 59.6 · IC025 +4.8 3/3 methods agree | Not in label — unassessed | serious n=40 | not reported in cached trials |
| Metastases to chest wall | 28 | 86.4 58.7–127.2ROR 86.5 · χ² 2,093 / p <1e-300 | 75.5 EB05 54.8 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=28 | not reported in cached trials |
| Metastases to thorax | 20 | 83.9 53.1–132.5ROR 84.0 · χ² 1,432 / p <1e-300 | 72.2 EB05 49.3 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=20 | not reported in cached trials |
| Secondary hypogonadism | 25 | 81.0 53.9–121.8ROR 81.1 · χ² 1,750 / p <1e-300 | 71.0 EB05 50.5 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious n=25 · ♀ 0% (drug 93%) · 100% clinician | not reported in cached trials |
| Pseudocellulitis | 16 | 80.3 48.3–133.7ROR 80.4 · χ² 1,085 / p 2e-238 | 68.5 EB05 44.7 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Metastases to the mediastinum | 31 | 79.3 55.0–114.3ROR 79.4 · χ² 2,143 / p <1e-300 | 70.3 EB05 51.9 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=31 | not reported in cached trials |
| Respiratory syncytial virus test positive | 52 | 78.2 59.0–103.8ROR 78.4 · χ² 3,598 / p <1e-300 | 70.7 EB05 56.0 · IC025 +5.0 3/3 methods agree | Lab value / disease marker | serious n=52 | not reported in cached trials |
| Hormone receptor positive breast cancer | 16 | 63.5 38.3–105.4ROR 63.6 · χ² 867 / p 9e-191 | 55.9 EB05 36.5 · IC025 +3.6 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=16 | not reported in cached trials |
| Breast cancer recurrent | 190 | 63.0 54.5–73.0ROR 63.6 · χ² 10,835 / p <1e-300 | 58.9 EB05 52.2 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=189 | not reported in cached trials |
| Tumour marker abnormal | 20 | 62.3 39.7–97.9ROR 62.4 · χ² 1,077 / p 2e-236 | 55.7 EB05 38.1 · IC025 +3.9 3/3 methods agree | Lab value / disease marker | serious n=19 | not reported in cached trials |
| Metastases to pelvis | 35 | 57.7 41.0–81.1ROR 57.8 · χ² 1,787 / p <1e-300 | 53.0 EB05 39.8 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=35 | not reported in cached trials |
| Scan abnormal | 20 | 56.3 35.9–88.4ROR 56.4 · χ² 976 / p 2e-214 | 50.9 EB05 34.8 · IC025 +3.8 3/3 methods agree | Lab value / disease marker | serious n=20 | not reported in cached trials |
| Metastases to bone | 789 | 49.8 46.4–53.4ROR 51.7 · χ² 35,861 / p <1e-300 | 47.4 EB05 44.6 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious PRR 37.5 | not reported in cached trials |
| Metastases to ovary | 15 | 48.8 29.0–81.9ROR 48.8 · χ² 624 / p 6e-138 | 44.1 EB05 28.4 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Urinary tract disorder | 202 | 46.2 40.1–53.2ROR 46.6 · χ² 8,483 / p <1e-300 | 44.0 EB05 39.1 · IC025 +5.1 3/3 methods agree | Labeled (related wording) related wording | serious n=202 · 96% clinician | not reported in cached trials |
| Metastases to spine | 147 | 45.1 38.2–53.1ROR 45.4 · χ² 6,011 / p <1e-300 | 42.9 EB05 37.4 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious n=147 | not reported in cached trials |
| Invasive lobular breast carcinoma | 20 | 39.9 25.5–62.4ROR 39.9 · χ² 691 / p 1e-152 | 37.1 EB05 25.4 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=19 | not reported in cached trials |
| Breast cancer metastatic | 408 | 38.8 35.2–42.8ROR 39.6 · χ² 14,432 / p <1e-300 | 37.3 EB05 34.4 · IC025 +5.0 3/3 methods agree | Likely indication confounding term in indications | serious PRR 29.6 | not reported in cached trials |
| Blood albumin abnormal | 19 | 37.8 23.9–59.8ROR 37.8 · χ² 620 / p 3e-137 | 35.3 EB05 23.9 · IC025 +3.5 3/3 methods agree | Lab value / disease marker | serious n=19 | not reported in cached trials |
| Invasive breast carcinoma | 15 | 37.0 22.1–61.9ROR 37.0 · χ² 472 / p 6e-105 | 34.3 EB05 22.0 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=14 | not reported in cached trials |
| Metastases to pleura | 37 | 36.2 26.1–50.2ROR 36.2 · χ² 1,187 / p 3e-260 | 34.4 EB05 26.0 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=37 · 100% clinician | not reported in cached trials |
| Hair disorder | 280 | 34.1 30.3–38.4ROR 34.6 · χ² 8,673 / p <1e-300 | 32.9 EB05 29.8 · IC025 +4.8 3/3 methods agree | Labeled (related wording) related wording | – | not reported in cached trials |
| Tumour marker increased | 154 | 32.5 27.7–38.1ROR 32.7 · χ² 4,518 / p <1e-300 | 31.4 EB05 27.4 · IC025 +4.6 3/3 methods agree | Lab value / disease marker | serious n=134 | not reported in cached trials |
| Metastases to bone marrow | 16 | 32.2 19.6–53.0ROR 32.3 · χ² 439 / p 9e-98 | 30.2 EB05 19.7 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Tonsillar disorder | 35 | 31.4 22.4–43.9ROR 31.4 · χ² 968 / p 9e-213 | 30.0 EB05 22.5 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=35 · 100% clinician | not reported in cached trials |
| Haemorrhagic stroke | 242 | 31.2 27.5–35.4ROR 31.5 · χ² 6,827 / p <1e-300 | 30.2 EB05 27.1 · IC025 +4.6 3/3 methods agree | Not in label — unassessed | serious PRR 23.7 · 91% clinician | not reported in cached trials |
| Metastases to lung | 353 | 31.0 27.9–34.4ROR 31.5 · χ² 9,903 / p <1e-300 | 30.0 EB05 27.5 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious PRR 23.7 | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Anastrozole as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (0 of 40 signal terms matched).
- NCT00066573 — Exemestane or Anastrozole in Treating Postmenopausal Women Who Have Undergone Surgery for Primary Breast Cance (N=7576, PHASE3; 62 AE terms posted; arms: Exemestane; Anastrozole)
- NCT01272037 — Tamoxifen Citrate, Letrozole, Anastrozole, or Exemestane With or Without Chemotherapy in Treating Patients Wit (N=5018, PHASE3; 16 AE terms posted; arms: Chemo and Endocrine Therapy; Endocrine Therapy Alone)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Fatigue (tiredness) | 2,364 | 3.0 2.9–3.1ROR 3.2 · χ² 3,256 / p <1e-300 | 3.0 EB05 2.9 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.2 | NCT00066573: 1/3,761 (0.0%) on Anastrozole (serious AE) |
| Nausea | 1,887 | 2.4 2.3–2.5ROR 2.5 · χ² 1,523 / p <1e-300 | 2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.6 | NCT00066573: 442/3,759 (11.8%) on Anastrozole |
| Diarrhoea (diarrhea) | 1,792 | 2.7 2.6–2.9ROR 2.9 · χ² 2,041 / p <1e-300 | 2.7 EB05 2.6 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.8 | NCT00066573: 414/3,759 (11.0%) on Anastrozole |
| Arthralgia (joint pain) | 1,575 | 3.7 3.6–3.9ROR 4.0 · χ² 3,221 / p <1e-300 | 3.7 EB05 3.6 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.1 | not reported in cached trials |
| Alopecia (hair loss) | 1,444 | 7.3 6.9–7.6ROR 7.7 · χ² 7,804 / p <1e-300 | 7.2 EB05 6.9 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 7.2 | NCT00066573: 212/3,759 (5.6%) on Anastrozole |
| Headache | 1,183 | 1.9 1.8–2.0ROR 1.9 · χ² 482 / p 4e-107 | 1.9 EB05 1.8 · IC025 +0.8 | Labeled adverse reaction exact term | serious PRR 2.3 | NCT00066573: 399/3,759 (10.6%) on Anastrozole |
| Dyspnoea (shortness of breath) | 1,087 | 1.9 1.8–2.0ROR 1.9 · χ² 467 / p 7e-104 | 1.9 EB05 1.8 · IC025 +0.8 | Labeled adverse reaction exact term | serious PRR 1.8 | NCT00066573: 652/3,759 (17.3%) on Anastrozole |
| Malignant neoplasm progression | 1,051 | 10.2 9.6–10.9ROR 10.7 · χ² 8,703 / p <1e-300 | 10.1 EB05 9.6 · IC025 +3.2 3/3 methods agree | Reporting / coding artifact | serious PRR 8.0 | not reported in cached trials |
| Asthenia (weakness) | 1,036 | 2.7 2.6–2.9ROR 2.8 · χ² 1,136 / p 2e-249 | 2.7 EB05 2.6 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.6 | not reported in cached trials |
| Dizziness | 1,033 | 2.0 1.9–2.2ROR 2.1 · χ² 560 / p 4e-124 | 2.0 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 2.2 | NCT00066573: 504/3,759 (13.4%) on Anastrozole |
| Pain | 1,029 | 1.6 1.5–1.7ROR 1.7 · χ² 267 / p 2e-60 | 1.6 EB05 1.6 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.6 | NCT00066573: 220/3,759 (5.9%) on Anastrozole |
| Vomiting | 1,008 | 2.1 2.0–2.2ROR 2.2 · χ² 604 / p 9e-134 | 2.1 EB05 2.0 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.1 | not reported in cached trials |
| Off label use (used outside approved label) | 913 | 1.0 1.0–1.1ROR 1.0 · χ² 1 / p 0.154 | 1.0 EB05 1.0 · IC025 -0.1 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.1 | not reported in cached trials |
| Drug ineffective (drug did not work) | 909 | 0.7 0.6–0.7ROR 0.7 · χ² 147 / p 3e-34 | 0.7 EB05 0.6 · IC025 -0.7 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.0 | not reported in cached trials |
| Malaise (feeling unwell) | 876 | 2.0 1.8–2.1ROR 2.0 · χ² 420 / p 2e-93 | 2.0 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 2.2 | not reported in cached trials |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Performance enhancing product use — n=20, PRR 265.5
- Amaurosis fugax — n=222, PRR 258.0
- Pik3ca-activated mutation — n=47, PRR 165.6
- Pseudocirrhosis — n=45, PRR 156.3
- Metastases to breast — n=31, PRR 102.9
- Chest wall mass — n=22, PRR 91.1
- Pneumonia haemophilus — n=40, PRR 87.9
- Metastases to chest wall — n=28, PRR 86.4
- Metastases to thorax — n=20, PRR 83.9
- Secondary hypogonadism — n=25, PRR 81.0
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Anastrozole?
In FDA FAERS, the most frequently co-reported reaction terms for Anastrozole are fatigue, nausea, diarrhoea, arthralgia, alopecia, headache. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Anastrozole have an FDA boxed warning?
No. The FDA label retrieved for Anastrozole has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Anastrozole causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 1d1d5818-1594-4f54-90a9-ae9a9afcdc67, effective 20260820; matched on
openfda.generic_name.exact:"ANASTROZOLE") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 1,190 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath - ClinicalTrials.gov API v2 (query
ANASTROZOLE, results-bearing studies sorted by enrollment)
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.