What the label lists and what reports show
Azacitidine side effects
Azacitidine's FDA label: “Most common adverse reactions (>30%) in adult patients with MDS by subcutaneous route are: nausea, anemia, thrombocytopenia, vomiting, pyrexia, leukopenia, diarrhea, injection site erythema, constipation, neutropenia and ecchymosis.” FAERS holds 29,495 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is febrile neutropenia (2,963 reports).
- Generic listed
- In shortage
Check it at the source: the azacitidine FDA label on DailyMed (effective January 29, 2024, Celgene Corporation); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of ONUREG?ONUREG can cause serious side effects, including: • New or worsening low white blood cell counts (neutropenia). New or worsening low white blood cell counts can be severe during treatment with ONUREG. If your white blood cell counts become very low, you are at increased risk for infections, including a severe infection of the blood called sepsis that can lead to death. Your healthcare provider will check your white blood cell counts before and during treatment with ONUREG. Your healthcare provider may prescribe a medicine to help increase your white blood cell count if needed. Tell your healthcare provider right away if you get any of the following symptoms: o fever o chills o body aches o shortness of breath o fast heartbeat o feeling very tired or weak o unusual headaches o lightheadedness or dizziness o confusion or grogginess • New or worsening low platelet counts (thrombocytopenia). […]
Source: FDA drug label (ONUREG), Celgene Corporation, effective June 12, 2026 (SPL set 0e95e33f-8aba-4f19-b332-2416580d358b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (>30%) in adult patients with MDS by subcutaneous route are: nausea, anemia, thrombocytopenia, vomiting, pyrexia, leukopenia, diarrhea, injection site erythema, constipation, neutropenia and ecchymosis.
Table 3: Most Frequently Observed Adverse Reactions (≥ 5% in All Subcutaneous VIDAZA…
| System Organ Class Preferred Term a | All VIDAZA b (N=220) | Observation c (N=92) |
|---|---|---|
| Anemia | 153 (70) | 59 (64) |
| Anemia aggravated | 12 (6) | 5 (5) |
| Febrile neutropenia | 36 (16) | 4 (4) |
| Leukopenia | 106 (48) | 27 (29) |
| Neutropenia | 71 (32) | 10 (11) |
| Thrombocytopenia | 144 (66) | 42 (46) |
| Abdominal tenderness | 26 (12) | 1 (1) |
| Constipation | 74 (34) | 6 (7) |
| Diarrhea | 80 (36) | 13 (14) |
| Gingival bleeding | 21 (10) | 4 (4) |
| Loose stools | 12 (6) | 0 |
| Mouth hemorrhage | 11 (5) | 1 (1) |
| Nausea | 155 (71) | 16 (17) |
| Stomatitis | 17 (8) | 0 |
| Vomiting | 119 (54) | 5 (5) |
| Chest pain | 36 (16) | 5 (5) |
| Injection site bruising | 31 (14) | 0 |
| Injection site erythema | 77 (35) | 0 |
| Injection site granuloma | 11 (5) | 0 |
| Injection site pain | 50 (23) | 0 |
| Injection site pigmentation changes | 11 (5) | 0 |
| Injection site pruritus | 15 (7) | 0 |
| Injection site reaction | 30 (14) | 0 |
| Injection site swelling | 11 (5) | 0 |
| Lethargy | 17 (8) | 2 (2) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following adverse reactions are described in other labeling sections: o Anemia, Neutropenia and Thrombocytopenia [see Warnings and Precautions ( 5.2 )] o Hepatotoxicity in Patients with Severe Pre-existing Hepatic Impairment [see Warnings and Precautions ( 5.3 )] o Renal Toxicity [see Warnings and Precautions ( 5.4 )] o Tumor Lysis Syndrome [see Warnings and Precautions ( 5.5 )] Most common adverse reactions (>30%) in adult patients with MDS by subcutaneous route are: nausea, anemia, thrombocytopenia, vomiting, pyrexia, leukopenia, diarrhea, injection site erythema, constipation, neutropenia and ecchymosis. Most common adverse reactions by intravenous route also included petechiae, rigors, weakness and hypokalemia ( 6.1 ). Most common adverse reactions (>30%) by intravenous route in pediatric patients with JMML are pyrexia, rash, upper respiratory tract infection, and anemia ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Bristol-Myers Squibb at 1-800-721-5072 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. …
Source: FDA drug label, NDA050794 (Bristol-Myers), as published by Celgene Corporation, effective January 29, 2024 (SPL set 3495a71a-cc04-4776-851f-f185956f32af), via openFDA; the full label on DailyMed
What do FAERS reports show?
29,495 reports list azacitidine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 10,775 are coded as a death and 12,837 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 18 reactions below, 11 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Azacitidine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions