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Anastrozole Tablets side effects: what 21,328 FDA adverse event reports show

Anastrozole Tablets · 1,190 reaction terms · 101,213 drug–reaction co-reports · data 2026-09-14
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Drug class

Aromatase Inhibitor

FDA label (Established Pharmacologic Class) · compare the class

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

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, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,150 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show:
ReactionReportsPRR 95% CI · ROR · χ²/pEBGM EB05 · IC025Label screenSerious-only & strataTrial cross-check
Performance enhancing product use20265.5
161.9–435.3ROR 265.7 · calibrated p 3e-10 ✓
174.2 EB05 119.1 · IC025 +4.4
3/3 methods agree
vs other Aromatase Inhibitors: only this drug
Not in label — unassessedserious n=20 · ♀ 0% (drug 93%) · 100% cliniciannot reported in cached trials
Amaurosis fugax222258.0
222.6–298.9ROR 260.7 · calibrated p 4e-11 ✓
200.4 EB05 179.3 · IC025 +6.9
3/3 methods agree
vs other Aromatase Inhibitors: PRR 1.0 (0.8–1.1)
Not in label — unassessedserious n=222 · 94% cliniciannot reported in cached trials
Vitreoretinal traction syndrome15188.8
108.6–328.2ROR 188.9 · calibrated p 8e-9 ✓
132.0 EB05 84.9 · IC025 +3.8
3/3 methods agree
vs other Aromatase Inhibitors: only this drug
Not in label — unassessedserious n=15not reported in cached trials
Pik3ca-activated mutation47165.6
121.6–225.6ROR 166.0 · calibrated p 4e-9 ✓
134.0 EB05 104.8 · IC025 +5.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.4 (0.3–0.5)
Not in label — unassessedserious n=47not reported in cached trials
Pseudocirrhosis45156.3
114.1–214.1ROR 156.6 · calibrated p 7e-9 ✓
127.6 EB05 99.2 · IC025 +5.3
3/3 methods agree
vs other Aromatase Inhibitors: PRR 1.0 (0.7–1.4)
Not in label — unassessedserious n=45 · 100% cliniciannot reported in cached trials
Human rhinovirus test positive51155.9
116.0–209.5ROR 156.3 · calibrated p 7e-9 ✓
128.1 EB05 101.2 · IC025 +5.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.2 (2.2–4.7)
Lab value / disease markerserious n=51not reported in cached trials
Carbohydrate antigen 15-3 increased77110.5
87.4–139.9ROR 110.9 · calibrated p 8e-8 ✓
97.0 EB05 80.1 · IC025 +5.5
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.4 (0.3–0.5)
Lab value / disease markerserious n=76not reported in cached trials
Pleural neoplasm16105.5
63.0–176.7ROR 105.6 · calibrated p 4e-7 ✓
85.8 EB05 56.0 · IC025 +3.8
3/3 methods agree
vs other Aromatase Inhibitors: PRR 1.2 (0.7–2.1)
Not in label — unassessedserious n=16not reported in cached trials
Viral test positive35103.7
73.2–146.9ROR 103.9 · calibrated p 2e-7 ✓
89.4 EB05 67.2 · IC025 +4.8
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.1 (2.0–4.8)
Lab value / disease markerserious n=34 · 100% cliniciannot reported in cached trials
Metastases to breast31102.9
71.1–148.9ROR 103.0 · calibrated p 2e-7 ✓
88.2 EB05 65.1 · IC025 +4.6
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.9 (2.4–6.3)
Not in label — unassessedserious n=31not reported in cached trials
Chest wall mass2291.1
58.9–141.0ROR 91.2 · calibrated p 7e-7 ✓
77.9 EB05 54.2 · IC025 +4.2
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.7 (2.1–6.5)
Not in label — unassessedserious n=22 · 100% cliniciannot reported in cached trials
Metastases to spinal cord1688.1
52.8–146.9ROR 88.2 · calibrated p 1e-6 ✓
74.0 EB05 48.3 · IC025 +3.7
3/3 methods agree
vs other Aromatase Inhibitors: only this drug
Not in label — unassessedserious n=16not reported in cached trials
Pneumonia haemophilus4087.9
63.6–121.5ROR 88.1 · calibrated p 6e-7 ✓
77.8 EB05 59.6 · IC025 +4.8
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.1 (2.1–4.7)
Not in label — unassessedserious n=40not reported in cached trials
Metastases to chest wall2886.4
58.7–127.2ROR 86.5 · calibrated p 8e-7 ✓
75.5 EB05 54.8 · IC025 +4.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.4–0.9)
Not in label — unassessedserious n=28not reported in cached trials
Metastases to thorax2083.9
53.1–132.5ROR 84.0 · calibrated p 1e-6 ✓
72.2 EB05 49.3 · IC025 +4.0
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.7 (0.4–1.1)
Not in label — unassessedserious n=20not reported in cached trials
Secondary hypogonadism2581.0
53.9–121.8ROR 81.1 · calibrated p 1e-6 ✓
71.0 EB05 50.5 · IC025 +4.3
3/3 methods agree
vs other Aromatase Inhibitors: PRR 4.0 (2.3–7.0)
Not in label — unassessedserious n=25 · ♀ 0% (drug 93%) · 100% cliniciannot reported in cached trials
Pseudocellulitis1680.3
48.3–133.7ROR 80.4 · calibrated p 2e-6 ✓
68.5 EB05 44.7 · IC025 +3.7
3/3 methods agree
vs other Aromatase Inhibitors: only this drug
Not in label — unassessedserious n=16not reported in cached trials
Metastases to the mediastinum3179.3
55.0–114.3ROR 79.4 · calibrated p 1e-6 ✓
70.3 EB05 51.9 · IC025 +4.5
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.7 (0.5–1.0)
Not in label — unassessedserious n=31not reported in cached trials
Respiratory syncytial virus test positive5278.2
59.0–103.8ROR 78.4 · calibrated p 1e-6 ✓
70.7 EB05 56.0 · IC025 +5.0
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.3 (2.3–4.8)
Lab value / disease markerserious n=52not reported in cached trials
Hormone receptor positive breast cancer1663.5
38.3–105.4ROR 63.6 · calibrated p 1e-5 ✓
55.9 EB05 36.5 · IC025 +3.6
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.4 (0.3–0.7)
Likely indication confounding
term in indications; also in warnings
serious n=16not reported in cached trials
Breast cancer recurrent19063.0
54.5–73.0ROR 63.6 · calibrated p 3e-6 ✓
58.9 EB05 52.2 · IC025 +5.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.7)
Not in label — unassessedserious n=189not reported in cached trials
Tumour marker abnormal2062.3
39.7–97.9ROR 62.4 · calibrated p 9e-6 ✓
55.7 EB05 38.1 · IC025 +3.9
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.4–1.0)
Lab value / disease markerserious n=19not reported in cached trials
Metastases to pelvis3557.7
41.0–81.1ROR 57.8 · calibrated p 1e-5 ✓
53.0 EB05 39.8 · IC025 +4.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.4–0.9)
Not in label — unassessedserious n=35not reported in cached trials
Scan abnormal2056.3
35.9–88.4ROR 56.4 · calibrated p 2e-5 ✓
50.9 EB05 34.8 · IC025 +3.8
3/3 methods agree
vs other Aromatase Inhibitors: only this drug
Lab value / disease markerserious n=20not reported in cached trials
Metastases to bone78949.8
46.4–53.4ROR 51.7 · calibrated p 1e-5 ✓
47.4 EB05 44.6 · IC025 +5.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.5)
Not in label — unassessedserious PRR 37.5not reported in cached trials
Metastases to ovary1548.8
29.0–81.9ROR 48.8 · calibrated p 5e-5 ✓
44.1 EB05 28.4 · IC025 +3.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 3.8 (1.9–7.6)
Not in label — unassessedserious n=15not reported in cached trials
Metastases to spine14745.1
38.2–53.1ROR 45.4 · calibrated p 3e-5 ✓
42.9 EB05 37.4 · IC025 +5.0
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.7)
Not in label — unassessedserious n=147not reported in cached trials
Invasive lobular breast carcinoma2039.9
25.5–62.4ROR 39.9 · calibrated p 1e-4 ✓
37.1 EB05 25.4 · IC025 +3.6
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.4 (0.3–0.6)
Not in label — unassessedserious n=19not reported in cached trials
Breast cancer metastatic40838.8
35.2–42.8ROR 39.6 · calibrated p 6e-5 ✓
37.3 EB05 34.4 · IC025 +5.0
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.3 (0.3–0.4)
Likely indication confounding
term in indications
serious PRR 29.6not reported in cached trials
Blood albumin abnormal1937.8
23.9–59.8ROR 37.8 · calibrated p 2e-4 ✓
35.3 EB05 23.9 · IC025 +3.5
3/3 methods agree
vs other Aromatase Inhibitors: only this drug
Lab value / disease markerserious n=19not reported in cached trials
Invasive breast carcinoma1537.0
22.1–61.9ROR 37.0 · calibrated p 2e-4 ✓
34.3 EB05 22.0 · IC025 +3.2
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.7 (0.4–1.2)
Not in label — unassessedserious n=14not reported in cached trials
Metastases to pleura3736.2
26.1–50.2ROR 36.2 · calibrated p 1e-4 ✓
34.4 EB05 26.0 · IC025 +4.0
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.3 (0.2–0.5)
Not in label — unassessedserious n=37 · 100% cliniciannot reported in cached trials
Tumour marker increased15432.5
27.7–38.1ROR 32.7 · calibrated p 2e-4 ✓
31.4 EB05 27.4 · IC025 +4.6
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.4 (0.3–0.5)
Lab value / disease markerserious n=134not reported in cached trials
Metastases to bone marrow1632.2
19.6–53.0ROR 32.3 · calibrated p 4e-4 ✓
30.2 EB05 19.7 · IC025 +3.2
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.8 (0.5–1.4)
Not in label — unassessedserious n=16not reported in cached trials
Tonsillar disorder3531.4
22.4–43.9ROR 31.4 · calibrated p 3e-4 ✓
30.0 EB05 22.5 · IC025 +3.9
3/3 methods agree
vs other Aromatase Inhibitors: PRR 4.0 (2.5–6.4)
Not in label — unassessedserious n=35 · 100% cliniciannot reported in cached trials
Haemorrhagic stroke24231.2
27.5–35.4ROR 31.5 · calibrated p 2e-4 ✓
30.2 EB05 27.1 · IC025 +4.6
3/3 methods agree
vs other Aromatase Inhibitors: PRR 1.0 (0.8–1.1)
Not in label — unassessedserious PRR 23.7 · 91% cliniciannot reported in cached trials
Metastases to lung35331.0
27.9–34.4ROR 31.5 · calibrated p 2e-4 ✓
30.0 EB05 27.5 · IC025 +4.7
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.6)
Not in label — unassessedserious PRR 23.7not 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 Tablets 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).

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.

ReactionReportsPRR 95% CI · ROR · χ²/pEBGM EB05 · IC025Label screenSerious-only & strataTrial cross-check
Fatigue (tiredness)2,3643.0
2.9–3.1ROR 3.2 · calibrated p 0.551
3.0 EB05 2.9 · IC025 +1.5
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.5)
Labeled adverse reaction
exact term
serious PRR 3.2NCT00066573: 1/3,761 (0.0%) on Anastrozole Tablets (serious AE)
Nausea1,8872.4
2.3–2.5ROR 2.5 · calibrated p 0.819
2.4 EB05 2.3 · IC025 +1.2
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.5)
Labeled adverse reaction
exact term
serious PRR 2.6NCT00066573: 442/3,759 (11.8%) on Anastrozole Tablets
Diarrhoea (diarrhea)1,7922.7
2.6–2.9ROR 2.9 · calibrated p 0.658
2.7 EB05 2.6 · IC025 +1.4
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 2.8NCT00066573: 414/3,759 (11.0%) on Anastrozole Tablets
Arthralgia (joint pain)1,5753.7
3.6–3.9ROR 4.0 · calibrated p 0.384
3.7 EB05 3.6 · IC025 +1.8
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 4.1not reported in cached trials
Alopecia (hair loss)1,4447.3
6.9–7.6ROR 7.7 · calibrated p 0.074
7.2 EB05 6.9 · IC025 +2.8
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 7.2NCT00066573: 212/3,759 (5.6%) on Anastrozole Tablets
Headache1,1831.9
1.8–2.0ROR 1.9 · calibrated p 0.894
1.9 EB05 1.8 · IC025 +0.8
vs other Aromatase Inhibitors: PRR 0.7 (0.6–0.7)
Labeled adverse reaction
exact term
serious PRR 2.3NCT00066573: 399/3,759 (10.6%) on Anastrozole Tablets
Dyspnoea (shortness of breath)1,0871.9
1.8–2.0ROR 1.9 · calibrated p 0.910
1.9 EB05 1.8 · IC025 +0.8
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 1.8NCT00066573: 652/3,759 (17.3%) on Anastrozole Tablets
Malignant neoplasm progression1,05110.2
9.6–10.9ROR 10.7 · calibrated p 0.025 ✓
10.1 EB05 9.6 · IC025 +3.2
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.4 (0.3–0.4)
Reporting / coding artifactserious PRR 8.0not reported in cached trials
Asthenia (weakness)1,0362.7
2.6–2.9ROR 2.8 · calibrated p 0.695
2.7 EB05 2.6 · IC025 +1.3
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 2.6not reported in cached trials
Dizziness1,0332.0
1.9–2.2ROR 2.1 · calibrated p 0.995
2.0 EB05 1.9 · IC025 +0.9
vs other Aromatase Inhibitors: PRR 0.6 (0.6–0.7)
Labeled adverse reaction
exact term
serious PRR 2.2NCT00066573: 504/3,759 (13.4%) on Anastrozole Tablets
Pain1,0291.6
1.5–1.7ROR 1.7 · calibrated p 0.756
1.6 EB05 1.6 · IC025 +0.6
vs other Aromatase Inhibitors: PRR 0.5 (0.5–0.5)
Labeled adverse reaction
exact term
serious PRR 1.6NCT00066573: 220/3,759 (5.9%) on Anastrozole Tablets
Vomiting1,0082.1
2.0–2.2ROR 2.2 · calibrated p 0.966
2.1 EB05 2.0 · IC025 +1.0
3/3 methods agree
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 2.1not reported in cached trials
Off label use (used outside approved label)9131.0
1.0–1.1ROR 1.0 · calibrated p 0.330
1.0 EB05 1.0 · IC025 -0.1
PRR-only: not supported by EBGM or IC
vs other Aromatase Inhibitors: PRR 0.6 (0.6–0.7)
Reporting / coding artifactserious PRR 1.1not reported in cached trials
Drug ineffective (drug did not work)9090.7
0.6–0.7ROR 0.7 · calibrated p 0.113
0.7 EB05 0.6 · IC025 -0.7
PRR-only: not supported by EBGM or IC
vs other Aromatase Inhibitors: PRR 0.7 (0.7–0.8)
Reporting / coding artifactserious PRR 1.0not reported in cached trials
Malaise (feeling unwell)8762.0
1.8–2.1ROR 2.0 · calibrated p 0.945
2.0 EB05 1.9 · IC025 +0.9
vs other Aromatase Inhibitors: PRR 0.6 (0.5–0.6)
Labeled adverse reaction
exact term
serious PRR 2.2not 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.

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 Tablets?

In FDA FAERS, the most frequently co-reported reaction terms for Anastrozole Tablets 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 Tablets have an FDA boxed warning?

No. The FDA label retrieved for Anastrozole Tablets has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Anastrozole Tablets 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

Page generated 2026-10-14. 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.