What the label lists and what reports show
Gemtuzumab ozogamicin side effects
Gemtuzumab ozogamicin's FDA label: “The most common adverse reactions (greater than 15%) were hemorrhage, infection, fever, nausea, vomiting, constipation, headache, increased AST, increased ALT, rash, mucositis, febrile neutropenia, and decreased appetite ( 6 ).” FAERS holds 3,635 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 (697 reports).
- No generic listed
- Boxed warning
Check it at the source: the gemtuzumab ozogamicin FDA label on DailyMed (effective December 19, 2025, 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 adverse reactions (greater than 15%) were hemorrhage, infection, fever, nausea, vomiting, constipation, headache, increased AST, increased ALT, rash, mucositis, febrile neutropenia, and decreased appetite ( 6 ).
Table 5. Grade 3 and Higher Adverse Reactions (≥5%) in Patients with Newly-Diagnosed De Novo AML in AAML0531 During Treatment Cycles with MYLOTARG
| Reaction | MYLOTARG + Chemotherapy N = 520 n (%) | Chemotherapy alone N = 517 n (%) | MYLOTARG + Chemotherapy N = 326 n (%) | Chemotherapy alone N = 304 n (%) |
|---|---|---|---|---|
| Infection Grouped term consisting of multiple preferred terms | 186 (36%) | 181 (35%) | 220 (67%) | 211 (69%) |
| Febrile neutropenia | 167 (32%) | 157 (30%) | 79 (24%) | 68 (22%) |
| Decreased appetite | 78 (15%) | 79 (15%) | 61 (19%) | 36 (12%) |
| Hyperglycemia | 59 (11%) | 55 (11%) | 36 (11%) | 28 (9%) |
| Mucositis | 55 (11%) | 64 (12%) | 25 (8%) | 15 (5%) |
| Hypoxia | 35 (7%) | 26 (5%) | 19 (6%) | 22 (7%) |
| Hemorrhage | 36 (7%) | 19 (4%) | 19 (6%) | 9 (3%) |
| Transaminase Increased | 33 (6%) | 24 (5%) | 23 (7%) | 13 (4%) |
| Diarrhea | 21 (4%) | 36 (7%) | 15 (5%) | 10 (3%) |
| Nausea | 21 (4%) | 18 (4%) | 23 (7%) | 10 (3%) |
| Hypotension | 16 (3%) | 26 (5%) | 28 (9%) | 23 (8%) |
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 clinically significant adverse reactions are described elsewhere in the labeling: • Hepatotoxicity, including VOD [see Warnings and Precautions (5.1) ] • Infusion-related reactions [see Warnings and Precautions (5.2) ] • Hemorrhage [see Warnings and Precautions (5.3) ] The most common adverse reactions (greater than 15%) were hemorrhage, infection, fever, nausea, vomiting, constipation, headache, increased AST, increased ALT, rash, mucositis, febrile neutropenia, and decreased appetite ( 6 ). 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. Combination Therapy in Newly-Diagnosed De Novo CD33-positive AML The safety of MYLOTARG in first-line combination therapy was evaluated in two prospective clinical trials, Study ALFA-0701 in adults and Study AAML0531 in pediatric patients. …
Source: FDA drug label, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective December 19, 2025 (SPL set 32fd2bb2-1cfa-4250-feb8-d7956c794e05), via openFDA; the full label on DailyMed
What do FAERS reports show?
3,635 reports list gemtuzumab ozogamicin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 1,126 are coded as a death and 1,745 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 21 reactions below, 12 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?
- Gemtuzumab 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