What the label lists and what reports show
Nelarabine side effects
Nelarabine's FDA label: “The most common (≥ 20%) adverse reactions were: • Adult: anemia, thrombocytopenia, neutropenia, nausea, diarrhea, vomiting, constipation, fatigue, pyrexia, cough, and dyspnea.” FAERS holds 956 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 (75 reports).
- Generic listed
- Boxed warning
Check it at the source: the nelarabine FDA label on DailyMed (effective March 31, 2025, Sandoz Inc); 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 ARRANON?ARRANON may cause serious nervous system problems. See “ What is the most important information I should know about ARRANON? ” ARRANON may also cause: • decreased blood counts such as low red blood cells, low white blood cells, and low platelets. Blood tests should be done regularly to check blood counts. Call the doctor right away if you or your child: • is more tired than usual, pale, or has trouble breathing • has a fever or other signs of an infection • bruises easy or has any unusual bleeding • stomach area problems such as nausea, vomiting, diarrhea, and constipation • headache • sleepiness • blurry eyesight Call your doctor right away if you experience unexplained muscle pain, tenderness, or weakness while taking ARRANON. This is because on rare occasions, muscle problems can be serious. These are not all the side effects associated with ARRANON. […]
Source: FDA drug label, Sandoz Inc, effective March 31, 2025 (SPL set 0f9051de-5c4d-4c0f-8c19-e15214498cca), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common (≥ 20%) adverse reactions were: • Adult: anemia, thrombocytopenia, neutropenia, nausea, diarrhea, vomiting, constipation, fatigue, pyrexia, cough, and dyspnea.
Table 1. Most Commonly Reported (≥ 5% Overall) Adverse Reactions in Adult Patients Treated With 1,500 mg/m 2 of ARRANON Administered by Intravenous Infusion Over 2 Hours on Days 1, 3, and 5 Repeated Every 21 Days
| Body System Adverse Reaction | Grade 3 % | Grades 4 and 5 a % | All Grades % |
|---|---|---|---|
| Anemia | 20 | 14 | 99 |
| Thrombocytopenia | 37 | 22 | 86 |
| Neutropenia | 14 | 49 | 81 |
| Febrile neutropenia | 9 | 1 | 12 |
| Sinus tachycardia | 1 | 0 | 8 |
| Nausea | 0 | 0 | 41 |
| Diarrhea | 1 | 0 | 22 |
| Vomiting | 1 | 0 | 22 |
| Constipation | 1 | 0 | 21 |
| Abdominal pain | 1 | 0 | 9 |
| Stomatitis | 1 | 0 | 8 |
| Abdominal distension | 0 | 0 | 6 |
| Fatigue | 10 | 2 | 50 |
| Pyrexia | 5 | 0 | 23 |
| Asthenia | 0 | 1 | 17 |
| Edema, peripheral | 0 | 0 | 15 |
| Edema | 0 | 0 | 11 |
| Pain | 3 | 0 | 11 |
| Rigors | 0 | 0 | 8 |
| Gait, abnormal | 0 | 0 | 6 |
| Chest pain | 0 | 0 | 5 |
| Noncardiac chest pain | 0 | 1 | 5 |
| Infection | 2 | 1 | 9 |
| Pneumonia | 4 | 1 | 8 |
| Sinusitis | 1 | 0 | 7 |
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 discussed in greater detail in other sections of the label: • Neurologic [see Boxed Warning, Warnings and Precautions (5.1)] • Hematologic [see Warnings and Precautions (5.2)] • Tumor Lysis Syndrome [see Warnings and Precautions (5.4)] • Effects on Ability to Drive and Use Machines [see Warnings and Precautions (5.6)] The most common (≥ 20%) adverse reactions were: • Adult: anemia, thrombocytopenia, neutropenia, nausea, diarrhea, vomiting, constipation, fatigue, pyrexia, cough, and dyspnea. ( 6.1 ) • Pediatric: anemia, neutropenia, thrombocytopenia, and leukopenia. ( 6.1 ) The most common (> 10%) neurological adverse reactions were: • Adult: somnolence, dizziness, peripheral neurologic disorders, hypoesthesia, headache, and paresthesia. ( 6.1 ) • Pediatric: headache and peripheral neurologic disorders. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Sandoz Inc. at 1-800-525-8747 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 with rates in the clinical trials of another drug and may not reflect the rates observed in practice. …
Source: FDA drug label, Sandoz Inc, effective March 31, 2025 (SPL set 0f9051de-5c4d-4c0f-8c19-e15214498cca), via openFDA; the full label on DailyMed
What do FAERS reports show?
956 reports list nelarabine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 210 are coded as a death and 321 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 23 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?
- Nelarabine: 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