What the label lists and what reports show
Alglucosidase alfa side effects
Alglucosidase alfa's FDA label: “The most frequently reported adverse reactions (≥5%) in clinical trials were hypersensitivity reactions and included: anaphylaxis, rash, pyrexia, flushing/feeling hot, urticaria, headache, hyperhidrosis, nausea, cough, decreased oxygen saturation …” FAERS holds 2,392 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 (172 reports).
- No generic listed
- Boxed warning
Check it at the source: the alglucosidase alfa FDA label on DailyMed (effective January 10, 2025, Genzyme Corporation); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe most frequently reported adverse reactions (≥5%) in clinical trials were hypersensitivity reactions and included: anaphylaxis, rash, pyrexia, flushing/feeling hot, urticaria, headache, hyperhidrosis, nausea, cough, decreased oxygen saturation, tachycardia, tachypnea, chest discomfort, dizziness, muscle twitching, agitation, cyanosis, erythema, hypertension/increased blood pressure, pallor, rigors, tremor, vomiting, fatigue, and myalgia.
Table 2: Adverse Reactions that Occurred in at Least 5% of Alglucosidase Alfa-Treated Infantile-Onset Patients in Trials 1 and 2
| Reaction | Number of Patients (N=39) n (%) |
|---|---|
| Adverse Reaction | 20 (51) |
| Rash (including rash erythematous, rash macular and maculopapular) | 7 (18) |
| Pyrexia | 6 (15) |
| Urticaria | 5 (13) |
| Flushing | 5 (13) |
| Hypertension/Increased Blood Pressure | 4 (10) |
| Decreased Oxygen Saturation | 3 (8) |
| Cough | 3 (8) |
| Tachypnea | 3 (8) |
| Tachycardia | 3 (8) |
| Erythema | 2 (5) |
| Vomiting | 2 (5) |
| Rigors | 2 (5) |
| Pallor | 2 (5) |
| Cyanosis | 2 (5) |
| Agitation | 2 (5) |
| Tremor | 2 (5) |
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) ] The most frequently reported adverse reactions (≥5%) in clinical trials were hypersensitivity reactions and included: anaphylaxis, rash, pyrexia, flushing/feeling hot, urticaria, headache, hyperhidrosis, nausea, cough, decreased oxygen saturation, tachycardia, tachypnea, chest discomfort, dizziness, muscle twitching, agitation, cyanosis, erythema, hypertension/increased blood pressure, pallor, rigors, tremor, vomiting, fatigue, and myalgia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Genzyme at 1-800-633-1610, option 1 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 clinical practice. …
Source: FDA drug label, Genzyme Corporation, effective January 10, 2025 (SPL set d6bfbc45-2d34-439e-8aad-59ee2d53d4df), via openFDA; the full label on DailyMed
What do FAERS reports show?
2,392 reports list alglucosidase alfa among the medicines taken, each a report of something that happened, not proof the medicine caused it; 116 are coded as a death and 530 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 20 reactions below, 10 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?
- Alglucosidase 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