Reported Reactions

Drugs › Nucleoside metabolic inhibitor

Generic name

Azacitidine: adverse event reports filed with FDA

14,969 reports list it as a suspect or interacting product, 2004–2026. Class: Nucleoside metabolic inhibitor. Also reported as Azacitidine Injectable, Azacitidine Oral, Azacitidine Injection.

14,969
reports as suspect product
0.1% of all reports · about 683 a year
1,830
reports, 12 months to June 2026
1,698 in the 12 months before
98%
marked serious by the reporter
92.2% across the class
32.3%
record death among outcomes, as reported
4,837 reports · not verified by FDA

14,969 adverse event reports received by FDA list azacitidine, a generic name as a suspect or interacting product, from August 2004 to June 2026. A further 4,283 reports list it only as a concomitant medication, and those are not counted in the figures on this page.

In the 12 months to June 2026, 1,830 reports listed it, close to the 1,698 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 683 reports a year and 0.1% of the 20,646,523 reports in the database, and 4.8% of the reports for the nucleoside metabolic inhibitor class. How many people take it is not in the data, so a count is not a rate of occurrence.

The MedDRA terms listed most often are febrile neutropenia (12%), myelosuppression (8.3%) and death (7.9%). A report can list several reactions, so shares add to more than 100%; 1,370 different terms appear across these reports. Febrile neutropenia is recorded in 12% of these reports, a larger share than in the median nucleoside metabolic inhibitor drug (5%).

98% of the reports are marked serious by the reporter (92.2% across the class); 32.3% record death among the outcomes and 50% record hospitalisation, as reported. 46.5% of the reports came from other health professionals, and the largest patient age group is 65 to 74 (27.4%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."

Reports by month, five years

0110219Jul 2021: 118Aug 2021: 151Sep 2021: 191Oct 2021: 208Nov 2021: 148Dec 2021: 1502022Jan 2022: 156Feb 2022: 126Mar 2022: 165Apr 2022: 166May 2022: 214Jun 2022: 219Jul 2022: 146Aug 2022: 208Sep 2022: 151Oct 2022: 139Nov 2022: 141Dec 2022: 1222023Jan 2023: 116Feb 2023: 142Mar 2023: 173Apr 2023: 115May 2023: 166Jun 2023: 154Jul 2023: 122Aug 2023: 98Sep 2023: 122Oct 2023: 142Nov 2023: 197Dec 2023: 1352024Jan 2024: 144Feb 2024: 140Mar 2024: 179Apr 2024: 159May 2024: 150Jun 2024: 122Jul 2024: 108Aug 2024: 140Sep 2024: 137Oct 2024: 144Nov 2024: 130Dec 2024: 1362025Jan 2025: 200Feb 2025: 159Mar 2025: 161Apr 2025: 134May 2025: 143Jun 2025: 106Jul 2025: 159Aug 2025: 146Sep 2025: 190Oct 2025: 171Nov 2025: 150Dec 2025: 1662026Jan 2026: 143Feb 2026: 124Mar 2026: 165Apr 2026: 134May 2026: 117Jun 2026: 165

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

09771,9532004: 220042005: 122006: 132007: 1420072008: 162009: 452010: 8220102011: 1142012: 932013: 8020132014: 2942015: 7492016: 59820162017: 7182018: 7482019: 79020192020: 9932021: 1,5512022: 1,95320222023: 1,6822024: 1,6892025: 1,88520252026: 848

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Azacitidine reports recording the termmedian drug in nucleoside metabolic inhibitor

  1. Febrile neutropeniafever with low white blood cells12%1,800
  2. Deaththe patient died; cause not stated by this term7.9%1,189
  3. Neutropenialow neutrophils, a type of white blood cell7.5%1,122
  4. Pneumonialung infection6.2%935
  5. Off label useused for a purpose or in a way not on the label6%893
  6. Thrombocytopenialow platelets5.6%840
  7. Pyrexiafever5.3%797
  8. Drug ineffectivethe medicine did not work as expected5.3%795
  9. Anaemialow red blood cells4.5%673
  10. Sepsisa severe body-wide response to infection4%602
  11. Infectionan infection, type not specified3.6%532
  12. Pancytopenialow counts of all blood cells3.1%470
  13. Disease progressionthe disease advanced2.7%399
  14. Septic shockshock arising from infection2.5%368
  15. Cytopenia2.4%363
  16. Platelet count decreasedlow platelet count2.4%360
  17. Nauseafeeling sick2.4%355
  18. Diarrhoealoose or frequent stools2.3%343
  19. White blood cell count decreasedlow white cell count2.2%322
  20. Acute myeloid leukaemia recurrent1.9%284
  21. Fatiguetiredness1.8%263
  22. Acute kidney injurysudden loss of kidney function1.6%238
  23. Vomitingbeing sick1.6%234
  24. Astheniaweakness or lack of energy1.5%231
  25. Respiratory failurethe lungs could not supply enough oxygen1.5%229

Top 30 of 1,370 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 19 drugs in the nucleoside metabolic inhibitor class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Outcomes recorded

Death32.3%4,837
Life-threatening11.5%1,728
Hospitalisation (initial or prolonged)50%7,481
Disability1.8%265
Congenital anomaly0%7
Other serious52.7%7,893
Not serious2%305

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 313,386 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Patient age

Under 20.4%61
2 to 110.9%139
12 to 171%146
18 to 445.2%772
45 to 6416.2%2,429
65 to 7427.4%4,107
75 and over27.2%4,071
Age not given21.7%3,244

Patient sex

Female33.7%5,050
Male52.3%7,825
Not given14%2,094

Who reported

Physician45.5%6,814
Pharmacist2.3%350
Other health professional46.5%6,961
Lawyer0%2
Consumer or non-health professional4.6%683
Not given1.1%159

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 21.2% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Acute myeloid leukaemia7,37249.2%
Myelodysplastic syndrome3,11920.8%
Chronic myelomonocytic leukaemia2611.7%
Chemotherapy1911.3%
Acute myeloid leukaemia recurrent1521%
Acute leukaemia1220.8%

The indication field is filled in by the reporter and is often blank; shares are of all 14,969 reports.

Drugs most often listed in the same reports

Drug (any role in the report)ReportsShare of Azacitidine reports
Venetoclax6,54843.7%
Allopurinol1,63410.9%
Cytarabine1,0156.8%
Posaconazole9476.3%
Ondansetron8615.8%
Acyclovir8225.5%
Venclexta7695.1%
Levofloxacin5833.9%
Furosemide5753.8%
Acetaminophen5653.8%

Other products listed in reports where Azacitidine is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.

In context

MeasureAzacitidineNucleoside metabolic inhibitorAll reports
Reports as suspect product14,969313,38620,646,523
Share of that pool—4.8%0.1%
Reports, latest 12 months1,830—1,332,454
Marked serious98%92.2%57.4%
Death recorded among outcomes, per 1,000 reports32321091
Hospitalisation recorded, per 1,000 reports500380213
Consumer-filed share4.6%11.4%45.8%
Top term, share of reportsFebrile neutropenia 12%median 5%0.3%

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Other drugs in the nucleoside metabolic inhibitor class

DrugName typeReportsLatest 12 monthsMarked serious
Fluorouracilgeneric60,4515,31596.1%
Capecitabinegeneric51,7833,28183.3%
Cytarabinegeneric50,7413,54597.9%
Gemcitabinegeneric33,1982,92097.9%
Xelodabrand32,27928073%
Fludarabinebrand20,2601,90098.7%
Gemcitabine hydrochloridegeneric12,3991,16497.1%
Mercaptopurinegeneric10,54050795.8%
Vidazabrand9,08735896.9%
Fludarabine phosphategeneric8,42641998.5%
Decitabinegeneric3,02625896.8%
Clofarabinegeneric2,0207796.5%
Purixangeneric7672981.5%
Onuregbrand7556949.8%
Pentostatingeneric6971691.7%

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.

Questions about Azacitidine reports

How many adverse event reports has FDA received for Azacitidine?

14,969 reports list Azacitidine as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 1,830 of them arrived in the latest 12 months. Another 4,283 list it only as a concomitant medication.

What reactions are recorded in Azacitidine reports?

febrile neutropenia (12%), myelosuppression (8.3%), death (7.9%), neutropenia (7.5%) and pneumonia (6.2%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Azacitidine was responsible.

How serious are the reports?

98% are marked serious by the reporter. Among the outcomes recorded, 32.3% of reports include death and 50% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.

Who files these reports?

other health professional (46.5%), physician (45.5%) and consumer or non-health professional (4.6%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Azacitidine rising?

1,830 reports in the 12 months to June 2026, close to the 1,698 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.

Do these reports show that Azacitidine was responsible for these reactions?

No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.

Is this a list of the side effects of Azacitidine?

No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.

How do I report an adverse event?

Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Azacitidine as a suspect or interacting product; reports listing it only as a concomitant medication (4,283) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.