[12][13] Miglustat is indicated to treat adults with mild to moderate type I Gaucher disease for whom enzyme replacement therapy is unsuitable.

[14] In the European Union, miglustat (Opfolda), in combination with cipaglucosidase alfa, is a long-term enzyme replacement therapy in adults with late-onset Pompe disease (acid α‑glucosidase [GAA] deficiency).

Common side effects include gastrointestinal effects (including diarrhea, stomach pain or bloating, gas, loss of appetite, weight loss, upset stomach, vomiting, constipation), dry mouth, muscular effects (including weakness, muscle cramps, especially in the legs, feeling of heaviness in the arms or legs, unsteadiness when walking), back pain, dizziness, nervousness, headache, memory problems, and difficult or irregular menstruation (period).

Miglustat, on the other hand, prevents the formation of the substance that builds up when the enzyme doesn't work; this is called substrate reduction therapy.

[23] Miglustat has been approved in the EU, Canada, and Japan for treating progressive neurological complications in people with Niemann–Pick disease, type C (NPC).