Azacitidine side effects: what 29,492 FDA adverse event reports show
Drug class
Nucleoside Metabolic Inhibitor
Brand names
Vidaza
Who reports
29,492 reports · 95% serious · 10,775 with death outcome · 39% female
Used for
VIDAZA is a nucleoside metabolic inhibitor indicated for the treatment of: • Adult patients with the following FAB myelodysplastic syndrome (MDS) subtypes: Refractory anemia (RA) or refractory anemia with ringed sideroblasts (RARS) (if accompanied by n.
What it is
VIDAZA (azacitidine for injection) contains azacitidine, which is a nucleoside metabolic inhibitor. Azacitidine is 4-amino-1-β-D-ribofuranosyl-s-triazin-2(1H)-one.
Boxed warning
None in the current label
Causality screen of the 40 strongest signals
What the badges mean
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- 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.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- 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. 1,049 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Flt3 gene mutation | 13 | 4,553.4 1,027.6–20,177.1ROR 4,555.4 · χ² 7,293 / p <1e-300 | 320.8 EB05 199.5 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Acute myeloid leukaemia refractory | 57 | 366.3 266.0–504.6ROR 367.0 · χ² 13,397 / p <1e-300 | 222.9 EB05 178.5 · IC025 +5.8 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=57 | not reported in cached trials |
| Allogenic stem cell transplantation | 51 | 346.9 248.0–485.1ROR 347.5 · χ² 11,533 / p <1e-300 | 213.8 EB05 168.9 · IC025 +5.7 3/3 methods agree | Not in label — unassessed | serious n=50 | not reported in cached trials |
| Corynebacterium bacteraemia | 25 | 307.2 192.0–491.6ROR 307.5 · χ² 5,094 / p <1e-300 | 184.0 EB05 131.1 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=25 · 100% clinician | not reported in cached trials |
| Acute myeloid leukaemia recurrent | 606 | 283.6 258.2–311.4ROR 289.5 · χ² 121,278 / p <1e-300 | 200.9 EB05 187.8 · IC025 +7.3 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=605 · 90% clinician | not reported in cached trials |
| Protothecosis | 25 | 257.5 162.9–407.3ROR 257.8 · χ² 4,485 / p <1e-300 | 165.0 EB05 117.5 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=25 · ♀ 100% (drug 39%) · 100% clinician | not reported in cached trials |
| Emphysematous cholecystitis | 13 | 246.1 130.8–463.0ROR 246.2 · χ² 2,170 / p <1e-300 | 144.2 EB05 89.7 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Myelodysplastic syndrome transformation | 129 | 231.7 189.9–282.7ROR 232.7 · χ² 22,095 / p <1e-300 | 170.0 EB05 146.8 · IC025 +6.4 3/3 methods agree | Likely indication confounding term in indications | serious n=129 · 96% clinician | not reported in cached trials |
| Blastic plasmacytoid dendritic cell neoplasia | 18 | 210.2 124.1–355.8ROR 210.3 · χ² 2,723 / p <1e-300 | 138.4 EB05 92.6 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=18 | not reported in cached trials |
| Transformation to acute myeloid leukaemia | 141 | 194.4 161.4–234.2ROR 195.4 · χ² 21,088 / p <1e-300 | 149.4 EB05 129.8 · IC025 +6.4 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=141 | not reported in cached trials |
| Cord blood transplant therapy | 18 | 188.2 111.9–316.6ROR 188.3 · χ² 2,496 / p <1e-300 | 128.6 EB05 86.1 · IC025 +4.1 3/3 methods agree | Reporting / coding artifact | serious n=18 | not reported in cached trials |
| Parainfluenza virus infection | 12 | 182.7 96.8–344.9ROR 182.8 · χ² 1,579 / p <1e-300 | 118.3 EB05 72.1 · IC025 +3.4 3/3 methods agree | Labeled (related wording) related wording | serious n=12 | not reported in cached trials |
| Blast cell count increased | 190 | 157.1 134.3–183.8ROR 158.2 · χ² 23,951 / p <1e-300 | 126.9 EB05 112.5 · IC025 +6.3 3/3 methods agree | Lab value / disease marker | serious n=186 | not reported in cached trials |
| Bacillus bacteraemia | 19 | 147.9 90.2–242.5ROR 148.0 · χ² 2,169 / p <1e-300 | 109.2 EB05 73.9 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=19 | not reported in cached trials |
| Chimerism | 14 | 132.5 74.9–234.6ROR 132.6 · χ² 1,428 / p <1e-300 | 97.2 EB05 61.5 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=14 | not reported in cached trials |
| Blast cell count decreased | 11 | 128.4 67.5–244.2ROR 128.5 · χ² 1,070 / p 6e-235 | 91.9 EB05 54.7 · IC025 +3.2 3/3 methods agree | Lab value / disease marker | serious n=10 | not reported in cached trials |
| Acute myeloid leukaemia | 2,204 | 117.3 112.3–122.5ROR 126.7 · χ² 217,741 / p <1e-300 | 100.5 EB05 97.1 · IC025 +6.6 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 61.0 · 93% clinician | not reported in cached trials |
| Leukostasis syndrome | 18 | 115.7 70.3–190.4ROR 115.8 · χ² 1,659 / p <1e-300 | 90.2 EB05 60.4 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=18 | not reported in cached trials |
| Chronic myelomonocytic leukaemia | 90 | 111.2 89.0–138.8ROR 111.5 · χ² 8,387 / p <1e-300 | 94.2 EB05 79.0 · IC025 +5.6 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=90 · ♀ 13% (drug 39%) | not reported in cached trials |
| Cytarabine syndrome | 10 | 107.8 55.4–209.7ROR 107.8 · χ² 826 / p 5e-182 | 79.8 EB05 46.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Erythroleukaemia | 10 | 107.8 55.4–209.7ROR 107.8 · χ² 826 / p 5e-182 | 79.8 EB05 46.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Myeloblast count increased | 10 | 104.6 53.8–203.2ROR 104.6 · χ² 804 / p 3e-177 | 78.0 EB05 45.3 · IC025 +3.0 3/3 methods agree | Lab value / disease marker | serious n=10 | not reported in cached trials |
| Differentiation syndrome | 89 | 101.0 80.9–126.2ROR 101.4 · χ² 7,618 / p <1e-300 | 86.8 EB05 72.7 · IC025 +5.5 3/3 methods agree | Labeled adverse reaction exact term | serious n=89 · 97% clinician | NCT03416179: 2/160 (1.2%) control (serious AE) |
| Minimal residual disease | 58 | 100.3 76.2–132.1ROR 100.5 · χ² 4,902 / p <1e-300 | 85.5 EB05 68.6 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=58 · 95% clinician | not reported in cached trials |
| Blood product transfusion dependent | 49 | 92.8 68.9–124.9ROR 92.9 · χ² 3,847 / p <1e-300 | 79.6 EB05 62.6 · IC025 +5.0 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=48 · ♀ 17% (drug 39%) · 92% clinician | not reported in cached trials |
| Congenital aplasia | 29 | 79.0 53.9–116.0ROR 79.1 · χ² 1,939 / p <1e-300 | 68.1 EB05 49.7 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=29 · ♀ 0% (drug 39%) · 100% clinician | not reported in cached trials |
| Myelodysplastic syndrome with excess blasts | 11 | 73.4 39.4–136.6ROR 73.4 · χ² 647 / p 5e-143 | 60.0 EB05 35.7 · IC025 +3.1 3/3 methods agree | Likely indication confounding term in indications | serious n=11 | not reported in cached trials |
| Chloroma | 39 | 72.3 52.0–100.5ROR 72.4 · χ² 2,421 / p <1e-300 | 63.7 EB05 48.6 · IC025 +4.6 3/3 methods agree | Not in label — unassessed | serious n=39 · 100% clinician | not reported in cached trials |
| Refractory anaemia with an excess of blasts | 25 | 60.8 40.4–91.5ROR 60.9 · χ² 1,299 / p 1e-284 | 53.9 EB05 38.4 · IC025 +4.1 3/3 methods agree | Likely indication confounding term in indications | serious n=25 · 100% clinician | not reported in cached trials |
| Geotrichum infection | 16 | 57.8 34.7–96.2ROR 57.8 · χ² 773 / p 2e-170 | 50.4 EB05 32.9 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Leukaemia cutis | 11 | 54.3 29.4–100.2ROR 54.3 · χ² 485 / p 7e-108 | 46.6 EB05 27.8 · IC025 +3.0 3/3 methods agree | Labeled adverse reaction exact term | serious n=11 | not reported in cached trials |
| Aeromonas infection | 12 | 52.2 29.0–93.9ROR 52.2 · χ² 514 / p 4e-114 | 45.4 EB05 27.7 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=12 | not reported in cached trials |
| Pneumonia adenoviral | 13 | 51.7 29.5–90.9ROR 51.8 · χ² 556 / p 3e-123 | 45.3 EB05 28.2 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Red blood cell transfusion | 27 | 51.4 34.8–76.0ROR 51.4 · χ² 1,196 / p 2e-262 | 46.5 EB05 33.5 · IC025 +4.0 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=27 | not reported in cached trials |
| Blast cells present | 29 | 45.8 31.4–66.6ROR 45.8 · χ² 1,150 / p 2e-252 | 41.9 EB05 30.6 · IC025 +4.0 3/3 methods agree | Lab value / disease marker | serious n=28 | not reported in cached trials |
| Adenoviral hepatitis | 14 | 45.6 26.6–78.3ROR 45.6 · χ² 532 / p 4e-118 | 40.7 EB05 25.8 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=14 | not reported in cached trials |
| Pneumonia fungal | 232 | 45.2 39.6–51.6ROR 45.5 · χ² 9,374 / p <1e-300 | 42.4 EB05 38.0 · IC025 +5.1 3/3 methods agree | Labeled (related wording) related wording | serious n=232 · 93% clinician | NCT03416179: 2/162 (1.2%) on Azacitidine; 2/201 (1.0%) control (serious AE) |
| Bacillus infection | 35 | 42.1 30.0–59.2ROR 42.2 · χ² 1,287 / p 4e-282 | 39.0 EB05 29.3 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=35 · 100% clinician | not reported in cached trials |
| Anorectal infection | 14 | 41.4 24.1–70.9ROR 41.4 · χ² 483 / p 2e-107 | 37.3 EB05 23.6 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=14 | NCT03416179: 1/201 (0.5%) control (serious AE) |
| Myelodysplastic syndrome | 772 | 40.0 37.3–43.0ROR 41.1 · χ² 27,768 / p <1e-300 | 37.9 EB05 35.7 · IC025 +5.1 3/3 methods agree | Likely indication confounding term in indications | serious PRR 22.5 | 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 Azacitidine 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 (3 of 40 signal terms matched).
- NCT03416179 — A Study Evaluating Intensive Chemotherapy With or Without Glasdegib or Azacitidine With or Without Glasdegib I (N=730, PHASE3; 334 AE terms posted; arms: Intensive Study: Glasdegib + Cytarabine ; Intensive Study: Placebo + Cytarabine + ; Non-intensive Study: Glasdegib + Azaciti; Non-intensive Study: Placebo + Azacitidi)
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 |
|---|---|---|---|---|---|---|
| Death | 3,359 | 2.8 2.7–2.9ROR 3.0 · χ² 3,974 / p <1e-300 | 2.8 EB05 2.7 · IC025 +1.4 3/3 methods agree | Outcome field, not a reaction | serious PRR 1.7 | NCT03416179: 4/162 (2.5%) on Azacitidine; 2/160 (1.2%) control (serious AE) |
| Febrile neutropenia | 2,962 | 33.3 32.1–34.4ROR 36.9 · χ² 88,723 / p <1e-300 | 31.8 EB05 30.8 · IC025 +4.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 19.3 · 96% clinician | NCT03416179: 20/160 (12.5%) on Azacitidine; 17/201 (8.5%) control (serious AE) |
| Acute myeloid leukaemia | 2,204 | 117.3 112.3–122.5ROR 126.7 · χ² 217,741 / p <1e-300 | 100.5 EB05 97.1 · IC025 +6.6 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 61.0 · 93% clinician | not reported in cached trials |
| Off label use (used outside approved label) | 2,018 | 1.7 1.6–1.7ROR 1.7 · χ² 543 / p 2e-120 | 1.7 EB05 1.6 · IC025 +0.7 | Reporting / coding artifact | serious PRR 1.6 | not reported in cached trials |
| Pneumonia (lung infection) | 2,000 | 4.4 4.2–4.6ROR 4.7 · χ² 5,338 / p <1e-300 | 4.4 EB05 4.2 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.8 · 92% clinician | NCT03416179: 36/160 (22.5%) on Azacitidine; 11/201 (5.5%) control (serious AE) |
| Neutropenia (low neutrophils (infection-fighting cells)) | 1,916 | 10.2 9.7–10.6ROR 10.8 · χ² 15,735 / p <1e-300 | 10.0 EB05 9.7 · IC025 +3.3 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 6.2 · 95% clinician | NCT03416179: 20/160 (12.5%) on Azacitidine; 17/201 (8.5%) control (serious AE) |
| Pyrexia (fever) | 1,659 | 3.4 3.3–3.6ROR 3.6 · χ² 2,869 / p <1e-300 | 3.4 EB05 3.3 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.6 | NCT03416179: 11/160 (6.9%) on Azacitidine; 6/201 (3.0%) control (serious AE) |
| Myelosuppression | 1,609 | 35.3 33.6–37.0ROR 37.2 · χ² 51,047 / p <1e-300 | 33.6 EB05 32.3 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious PRR 20.3 · 97% clinician | not reported in cached trials |
| Thrombocytopenia (low platelets) | 1,539 | 9.9 9.5–10.4ROR 10.4 · χ² 12,252 / p <1e-300 | 9.8 EB05 9.4 · IC025 +3.2 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 6.1 · 95% clinician | NCT03416179: 1/160 (0.6%) on Azacitidine; 3/201 (1.5%) control (serious AE) |
| Anaemia (low red blood cells) | 1,346 | 5.0 4.8–5.3ROR 5.2 · χ² 4,367 / p <1e-300 | 5.0 EB05 4.8 · IC025 +2.2 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 3.3 · 93% clinician | NCT03416179: 5/160 (3.1%) on Azacitidine; 1/201 (0.5%) control (serious AE) |
| Sepsis (blood infection) | 1,258 | 8.1 7.7–8.5ROR 8.4 · χ² 7,767 / p <1e-300 | 8.0 EB05 7.6 · IC025 +2.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.9 · 94% clinician | NCT03416179: 5/160 (3.1%) on Azacitidine; 2/201 (1.0%) control (serious AE) |
| Platelet count decreased | 1,251 | 8.4 8.0–8.9ROR 8.8 · χ² 8,138 / p <1e-300 | 8.3 EB05 8.0 · IC025 +3.0 3/3 methods agree | Labeled (related wording) related wording | serious PRR 6.0 | NCT03416179: 1/162 (0.6%) on Azacitidine (serious AE) |
| Drug ineffective (drug did not work) | 1,197 | 0.6 0.6–0.7ROR 0.6 · χ² 247 / p 5e-56 | 0.6 EB05 0.6 · IC025 -0.7 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.1 | not reported in cached trials |
| Infection | 1,116 | 5.5 5.2–5.9ROR 5.7 · χ² 4,141 / p <1e-300 | 5.5 EB05 5.2 · IC025 +2.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.2 | NCT03416179: 1/162 (0.6%) on Azacitidine; 5/160 (3.1%) control (serious AE) |
| Pancytopenia (all blood cells low) | 1,044 | 13.6 12.8–14.4ROR 14.0 · χ² 11,930 / p <1e-300 | 13.3 EB05 12.6 · IC025 +3.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 8.1 · 93% clinician | 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.
- Allogenic stem cell transplantation — n=51, PRR 346.9
- Corynebacterium bacteraemia — n=25, PRR 307.2
- Protothecosis — n=25, PRR 257.5
- Minimal residual disease — n=58, PRR 100.3
- Congenital aplasia — n=29, PRR 79.0
- Chloroma — n=39, PRR 72.3
- Bacillus infection — n=35, PRR 42.1
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 Azacitidine?
In FDA FAERS, the most frequently co-reported reaction terms for Azacitidine are febrile neutropenia, acute myeloid leukaemia, pneumonia, neutropenia, pyrexia, myelosuppression. 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 Azacitidine have an FDA boxed warning?
No. The FDA label retrieved for Azacitidine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Azacitidine 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 3495a71a-cc04-4776-851f-f185956f32af, effective 20240129; matched on
openfda.generic_name.exact:"AZACITIDINE") - 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, 1,089 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
AZACITIDINE, 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.