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Azacitidine side effects: what 29,492 FDA adverse event reports show

Azacitidine · Vidaza · 1,089 reaction terms · 84,182 drug–reaction co-reports · data 2026-09-14
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Drug class

Nucleoside Metabolic Inhibitor

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Vidaza

openFDA label

Who reports

29,492 reports · 95% serious · 10,775 with death outcome · 39% female

openFDA FAERS counts, all years, deduplication not applied

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.

FDA label, Indications and Usage

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.

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 adverse reaction 2Labeled (related wording) 2Likely indication confounding 11Reporting / coding artifact 1Lab value / disease marker 4Not in label — unassessed 20
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 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.

Show:
ReactionReportsPRR 95% CI · ROR · χ²/pEBGM EB05 · IC025Label screenSerious-only & strataTrial cross-check
Flt3 gene mutation134,553.4
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 — unassessedserious n=13not reported in cached trials
Acute myeloid leukaemia refractory57366.3
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=57not reported in cached trials
Allogenic stem cell transplantation51346.9
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 — unassessedserious n=50not reported in cached trials
Corynebacterium bacteraemia25307.2
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 — unassessedserious n=25 · 100% cliniciannot reported in cached trials
Acute myeloid leukaemia recurrent606283.6
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% cliniciannot reported in cached trials
Protothecosis25257.5
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 — unassessedserious n=25 · ♀ 100% (drug 39%) · 100% cliniciannot reported in cached trials
Emphysematous cholecystitis13246.1
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 — unassessedserious n=13not reported in cached trials
Myelodysplastic syndrome transformation129231.7
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% cliniciannot reported in cached trials
Blastic plasmacytoid dendritic cell neoplasia18210.2
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 — unassessedserious n=18not reported in cached trials
Transformation to acute myeloid leukaemia141194.4
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=141not reported in cached trials
Cord blood transplant therapy18188.2
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 artifactserious n=18not reported in cached trials
Blast cell count increased190157.1
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 markerserious n=186not reported in cached trials
Bacillus bacteraemia19147.9
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 — unassessedserious n=19not reported in cached trials
Chimerism14132.5
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 — unassessedserious n=14not reported in cached trials
Blast cell count decreased11128.4
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 markerserious n=10not reported in cached trials
Acute myeloid leukaemia2,204117.3
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% cliniciannot reported in cached trials
Leukostasis syndrome18115.7
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 — unassessedserious n=18not reported in cached trials
Chronic myelomonocytic leukaemia90111.2
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 syndrome10107.8
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 — unassessedserious n=10not reported in cached trials
Erythroleukaemia10107.8
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 — unassessedserious n=10not reported in cached trials
Myeloblast count increased10104.6
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 markerserious n=10not reported in cached trials
Differentiation syndrome89101.0
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% clinicianNCT03416179: 2/160 (1.2%) control (serious AE)
Minimal residual disease58100.3
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 — unassessedserious n=58 · 95% cliniciannot reported in cached trials
Blood product transfusion dependent4992.8
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% cliniciannot reported in cached trials
Congenital aplasia2979.0
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 — unassessedserious n=29 · ♀ 0% (drug 39%) · 100% cliniciannot reported in cached trials
Myelodysplastic syndrome with excess blasts1173.4
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=11not reported in cached trials
Chloroma3972.3
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 — unassessedserious n=39 · 100% cliniciannot reported in cached trials
Refractory anaemia with an excess of blasts2560.8
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% cliniciannot reported in cached trials
Geotrichum infection1657.8
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 — unassessedserious n=16not reported in cached trials
Leukaemia cutis1154.3
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=11not reported in cached trials
Aeromonas infection1252.2
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 — unassessedserious n=12not reported in cached trials
Pneumonia adenoviral1351.7
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 — unassessedserious n=13not reported in cached trials
Red blood cell transfusion2751.4
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=27not reported in cached trials
Blast cells present2945.8
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 markerserious n=28not reported in cached trials
Adenoviral hepatitis1445.6
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 — unassessedserious n=14not reported in cached trials
Bacillus infection3542.1
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 — unassessedserious n=35 · 100% cliniciannot reported in cached trials
Anorectal infection1441.4
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 — unassessedserious n=14NCT03416179: 1/201 (0.5%) control (serious AE)
Myelodysplastic syndrome77240.0
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 22.5not 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).

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
Death3,3592.8
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 reactionserious PRR 1.7NCT03416179: 4/162 (2.5%) on Azacitidine; 2/160 (1.2%) control (serious AE)
Febrile neutropenia2,96233.3
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% clinicianNCT03416179: 20/160 (12.5%) on Azacitidine; 17/201 (8.5%) control (serious AE)
Acute myeloid leukaemia2,204117.3
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% cliniciannot reported in cached trials
Off label use (used outside approved label)2,0181.7
1.6–1.7ROR 1.7 · χ² 543 / p 2e-120
1.7 EB05 1.6 · IC025 +0.7Reporting / coding artifactserious PRR 1.6not reported in cached trials
Pneumonia (lung infection)2,0004.4
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% clinicianNCT03416179: 36/160 (22.5%) on Azacitidine; 11/201 (5.5%) control (serious AE)
Neutropenia (low neutrophils (infection-fighting cells))1,91610.2
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% clinicianNCT03416179: 20/160 (12.5%) on Azacitidine; 17/201 (8.5%) control (serious AE)
Pyrexia (fever)1,6593.4
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 2.6NCT03416179: 11/160 (6.9%) on Azacitidine; 6/201 (3.0%) control (serious AE)
Myelosuppression1,60935.3
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 — unassessedserious PRR 20.3 · 97% cliniciannot reported in cached trials
Thrombocytopenia (low platelets)1,5399.9
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% clinicianNCT03416179: 1/160 (0.6%) on Azacitidine; 3/201 (1.5%) control (serious AE)
Anaemia (low red blood cells)1,3465.0
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% clinicianNCT03416179: 5/160 (3.1%) on Azacitidine; 1/201 (0.5%) control (serious AE)
Sepsis (blood infection)1,2588.1
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% clinicianNCT03416179: 5/160 (3.1%) on Azacitidine; 2/201 (1.0%) control (serious AE)
Drug ineffective (drug did not work)1,1970.6
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 artifactserious PRR 1.1not reported in cached trials
Infection1,1165.5
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 4.2NCT03416179: 1/162 (0.6%) on Azacitidine; 5/160 (3.1%) control (serious AE)
Pancytopenia (all blood cells low)1,04413.6
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% cliniciannot 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 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

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.