What the label lists and what reports show
Inotuzumab ozogamicin side effects
Inotuzumab ozogamicin's FDA label: “The most common (≥ 20%) adverse reactions, including laboratory abnormalities, in adult and pediatric patients are thrombocytopenia, pyrexia, neutropenia, infection, anemia, vomiting, leukopenia, hemorrhage, fatigue, nausea, febrile neutropenia, headache …” FAERS holds 2,937 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 (265 reports).
- No generic listed
- Boxed warning
Check it at the source: the inotuzumab ozogamicin FDA label on DailyMed (effective February 6, 2026, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most common (≥ 20%) adverse reactions, including laboratory abnormalities, in adult and pediatric patients are thrombocytopenia, pyrexia, neutropenia, infection, anemia, vomiting, leukopenia, hemorrhage, fatigue, nausea, febrile neutropenia, headache, transaminases increased, abdominal pain, and gamma-glutamyltransferase increased, and hyperbilirubinemia.
Table 9. Adverse Reactions (≥ 5%) in Pediatric Patients (N=53) With CD22-Positive Relapsed or Refractory ALL in Study WI203581 (ITCC-059)
| Reaction | Body System Adverse Reaction All Grades % | BESPONSA Monotherapy (N=53) ≥ Grade 3 % |
|---|---|---|
| Pyrexia | 49 | 4 |
| Edema Includes other related terms. | 19 | 0 |
| Fatigue | 17 | 0 |
| Pain | 15 | 2 |
| Chills | 8 | 0 |
| Anemia | 45 | 38 |
| Febrile neutropenia | 28 | 28 |
| Vomiting | 45 | 2 |
| Nausea | 32 | 0 |
| Abdominal pain | 25 | 2 |
| Constipation | 19 | 2 |
| Stomatitis | 17 | 6 |
| Diarrhea | 11 | 0 |
| Infection Infection includes any reported preferred terms for system organ class… | 43 | 23 |
| Hemorrhage Hemorrhage includes any reported PT terms within the hemorrhage terms (excl… | 42 | 6 |
| Hypotension | 6 | 4 |
| Headache | 21 | 0 |
| Rash | 19 | 4 |
| Pruritis | 9 | 0 |
| Hyperhidrosis | 6 | 0 |
| Pain in extremity | 19 | 2 |
| Back pain | 6 | 0 |
| Neck pain | 6 | 0 |
| Muscular weakness | 6 | 0 |
| Cough | 17 | 0 |
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, continuedADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the label: • Hepatotoxicity, including hepatic VOD (also known as SOS) [see Warnings and Precautions (5.1) ] • Increased risk of post-transplant non-relapse mortality [see Warnings and Precautions (5.2) ] • Myelosuppression [see Warnings and Precautions (5.3) ] • Infusion related reactions [see Warnings and Precautions (5.4) ] • QT interval prolongation [see Warnings and Precautions (5.5) ] The most common (≥ 20%) adverse reactions, including laboratory abnormalities, in adult and pediatric patients are thrombocytopenia, pyrexia, neutropenia, infection, anemia, vomiting, leukopenia, hemorrhage, fatigue, nausea, febrile neutropenia, headache, transaminases increased, abdominal pain, and gamma-glutamyltransferase increased, and hyperbilirubinemia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc at 1-800-438-1985 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, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective February 6, 2026 (SPL set cc7014b1-c775-411d-b374-8113248b4077), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,937 reports list inotuzumab ozogamicin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 996 are coded as a death and 1,184 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 22 reactions below, 15 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?
- Inotuzumab ozogamicin: 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