What the label lists and what reports show
Treosulfan side effects
Treosulfan's FDA label: “The most common adverse reactions (≥20%) are musculoskeletal pain, stomatitis, pyrexia, nausea, edema, infection, and vomiting.” FAERS holds 2,640 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 cytomegalovirus infection reactivation (271 reports).
- No generic listed
- Boxed warning
Check it at the source: the treosulfan FDA label on DailyMed (effective January 31, 2025, Medexus Pharma, Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (≥20%) are musculoskeletal pain, stomatitis, pyrexia, nausea, edema, infection, and vomiting.
Table 3: Adverse Reactions in ≥10% of Patients through Transplant Day +30 in Study MC-FludT.14/L Trial II
| Reaction | GRAFAPEX (N = 270) % | Busulfan (N = 283) % | GRAFAPEX (N = 270) % | Busulfan (N = 283) % |
|---|---|---|---|---|
| Musculoskeletal pain | 39 | 27 | 5 | 2 |
| Stomatitis | 38 | 48 | 6 | 7 |
| Pyrexia | 34 | 36 | 1 | 3 |
| Nausea | 33 | 41 | 3 | 6 |
| Edema | 29 | 18 | 0.7 | 1 |
| Infection 1 | 23 | 18 | 12 | 6 |
| Vomiting | 22 | 19 | 1 | 1 |
| Rash | 17 | 13 | 1 | 1 |
| Diarrhea | 17 | 18 | 1 | 1 |
| Headache | 16 | 18 | 1 | 1 |
| Febrile neutropenia | 15 | 11 | 15 | 11 |
| Abdominal pain | 15 | 13 | 3 | 2 |
| Hypertension | 14 | 21 | 8 | 10 |
| Hemorrhage | 14 | 14 | 1 | 1 |
| Fatigue | 13 | 15 | 1 | 0.4 |
| Constipation | 12 | 12 | 0.4 | 0 |
| Tachycardia | 10 | 5 | 1 | 2 |
| Hepatotoxicity | 10 | 8 | 4 | 3 |
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: Myelosuppression [see Warnings and Precautions ( 5.1 )] Seizures [see Warnings and Precautions ( 5.2 )] Skin Disorders [see Warnings and Precautions ( 5.3 )] Injection Site Reactions and Tissue Necrosis [see Warnings and Precautions ( 5.4 )] Secondary Malignancies [see Warnings and Precautions ( 5.5 )] The most common adverse reactions (≥20%) are musculoskeletal pain, stomatitis, pyrexia, nausea, edema, infection, and vomiting. ( 6.1 ) Selected Grade 3 or 4 nonhematological laboratory abnormalities are increased GGT, increased bilirubin, increased ALT, increased AST, and increased creatinine. To report SUSPECTED ADVERSE REACTIONS, contact Medexus Pharma, Inc. at 1-855-336 -3322 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, Medexus Pharma, Inc., effective January 31, 2025 (SPL set 2d06b03c-17aa-0492-e063-6294a90abd8f), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,640 reports list treosulfan among the medicines taken, each a report of something that happened, not proof the medicine caused it; 579 are coded as a death and 478 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, 5 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?
- Treosulfan: 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