What the label lists and what reports show
Elosulfase alfa side effects
Elosulfase alfa's FDA label: “Most common adverse reactions (≥10%) are: pyrexia, vomiting, headache, nausea, abdominal pain, chills, and fatigue.” FAERS holds 5,380 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 pyrexia (726 reports).
- No generic listed
- Boxed warning
Check it at the source: the elosulfase alfa FDA label on DailyMed (effective October 30, 2025, BioMarin Pharmaceutical Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥10%) are: pyrexia, vomiting, headache, nausea, abdominal pain, chills, and fatigue.
Table 3: Adverse Reactions That Occurred in the Placebo-Controlled Trial in At Least 10% of Patients in the VIMIZIM 2 mg/kg Once Per Week Group and with a Higher Incidence than in the Placebo Group
| Adverse Reaction | VIMIZIM 2 mg/kg once per week N= 58 n (%) | Placebo N= 59 n (%) |
|---|---|---|
| Pyrexia | 19 (33%) | 8 (14%) |
| Vomiting | 18 (31%) | 4 (7%) |
| Headache | 15 (26%) | 9 (15%) |
| Nausea | 14 (24%) | 4 (7%) |
| Abdominal pain | 12 (21%) | 1 (2%) |
| Chills | 6 (10%) | 1 (2%) |
| Fatigue | 6 (10%) | 2 (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 serious adverse reactions are described below and elsewhere in the labeling: Hypersensitivity Reactions Including Anaphylaxis [see Warnings and Precautions (5.1) ]. Risk of Acute Respiratory Complications [see Warnings and Precautions (5.2) ]. Spinal or Cervical Cord Compression [see Warnings and Precautions (5.3) ]. Most common adverse reactions (≥10%) are: pyrexia, vomiting, headache, nausea, abdominal pain, chills, and fatigue. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact BioMarin at 1-866-906-6100 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. A 24-week, randomized, double-blind, placebo-controlled clinical trial of VIMIZIM was conducted in 176 patients with MPS IVA, ages 5 to 57 years old. Approximately half of the patients (49%) were male. Of the 176 patients, 65% were White, 23% Asian, 3% Black, and 10% Other race. The majority of patients (78%) were non-Hispanic. Patients were randomized to three treatment groups: VIMIZIM 2 mg/kg once per week (n=58), VIMIZIM 2 mg/kg once every other week (n=59), or placebo (n=59). …
Source: FDA drug label, BioMarin Pharmaceutical Inc., effective October 30, 2025 (SPL set 0caa2565-12b2-0ad0-1f9a-273e81c3d4cc), via openFDA; the full label on DailyMed
What do FAERS reports show?
5,380 reports list elosulfase alfa among the medicines taken, each a report of something that happened, not proof the medicine caused it; 131 are coded as a death and 1,135 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 24 reactions below, 9 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?
- Elosulfase alfa: 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