What the label lists and what reports show
Miglustat side effects
Miglustat's FDA label: “The most common adverse reactions (incidence ≥5%) are: diarrhea, weight loss, stomach pain, gas, nausea and vomiting headache including migraine, tremor, leg cramps, dizziness, weakness, vision problems, thrombocytopenia, muscle cramps, back pain …” FAERS holds 1,154 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 diarrhoea (164 reports).
- Generic listed
Check it at the source: the miglustat FDA label on DailyMed (effective April 20, 2023, Actelion Pharmaceuticals US, 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 ZAVESCA?ZAVESCA may cause serious side effects including: Numbness, tingling, pain, or burning in your hands or feet (peripheral neuropathy). Call your healthcare provider right away if you get numbness, tingling, pain, or burning in your hands or feet. Your healthcare provider may test your nerves (neurological exam) before you start ZAVESCA and during treatment with ZAVESCA. New or worsening hand tremors (shaky movements). Tremors are common with ZAVESCA and may begin within the first month of starting treatment. Sometimes the tremors may go away between 1 to 3 months with continued treatment. Your healthcare provider may lower your dose or stop ZAVESCA if you develop new or worsening hand tremors. Call your healthcare provider right away if you get new hand tremors during treatment with ZAVESCA or if the hand tremors you already have get worse. […]
Source: FDA drug label, Actelion Pharmaceuticals US, Inc., effective April 20, 2023 (SPL set 817892d1-ee12-4632-85fc-57ccdf16d7b8), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (incidence ≥5%) are: diarrhea, weight loss, stomach pain, gas, nausea and vomiting headache including migraine, tremor, leg cramps, dizziness, weakness, vision problems, thrombocytopenia, muscle cramps, back pain, constipation, dry mouth, heaviness in arms and legs, memory loss, unsteady walking, anorexia, indigestion, paresthesia, stomach bloating, stomach pain not related to food, and menstrual changes ( 6.1 ).
A table the label prints in its adverse reactions section without a title; its column headings name the groups compared
This table is printed in the OPFOLDA label published by AMICUS THERAPEUTICS US, LLC of November 27, 2024; the label quoted above does not print one.
| Adverse Reaction | OPFOLDA in Combination with Pombiliti (n=85) N (%) | A Non-U.S.-Approved Alglucosidase alfa Product with Placebo (n=38) N (%) |
|---|---|---|
| Headache ∗ | 7 (8.2) | 3 (7.9) |
| Diarrhea | 5 (5.9) | 2 (5.3) |
| Dizziness | 4 (4.7) | 2 (5.3) |
| Dyspnea | 3 (3.5) | 0 |
| Abdominal distention | 3 (3.5) | 2 (5.3) |
| Pyrexia | 3 (3.5) | 1 (2.6) |
| Rash | 3 (3.5) | 0 |
| Abdominal pain | 2 (2.4) | 4 (10.5) |
| Nausea | 2 (2.4) | 5 (13.2) |
| Chills | 2 (2.4) | 0 |
| Dysgeusia | 2 (2.4) | 0 |
| Flushing | 2 (2.4) | 0 |
| Muscle spasms | 2 (2.4) | 0 |
| Pruritus | 2 (2.4) | 2 (5.3) |
| Tachycardia | 2 (2.4) | 0 |
| Urticaria | 2 (2.4) | 0 |
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: Peripheral Neuropathy [see Warnings and Precautions (5.1) ] Tremor [see Warnings and Precautions (5.2) ] Diarrhea and Weight Loss [see Warnings and Precautions (5.3) ] Reductions in Platelet Count [see Warnings and Precautions (5.4) ] The most common adverse reactions (incidence ≥5%) are: diarrhea, weight loss, stomach pain, gas, nausea and vomiting headache including migraine, tremor, leg cramps, dizziness, weakness, vision problems, thrombocytopenia, muscle cramps, back pain, constipation, dry mouth, heaviness in arms and legs, memory loss, unsteady walking, anorexia, indigestion, paresthesia, stomach bloating, stomach pain not related to food, and menstrual changes ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Janssen at 1-800-526-7736 (1-800- JANSSEN) 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, Actelion Pharmaceuticals US, Inc., effective April 20, 2023 (SPL set 817892d1-ee12-4632-85fc-57ccdf16d7b8), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,154 reports list miglustat among the medicines taken, each a report of something that happened, not proof the medicine caused it; 319 are coded as a death and 418 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 19 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?
- Miglustat: 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