Zavesca Side Effects

Generic Name: miglustat

Note: This document contains side effect information about miglustat. Some of the dosage forms listed on this page may not apply to the brand name Zavesca.

Some side effects of Zavesca may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to miglustat: oral capsule

Along with its needed effects, miglustat (the active ingredient contained in Zavesca) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking miglustat:

More common
  • Black, tarry stools
  • bleeding gums
  • blood in the urine or stools
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • diarrhea
  • pinpoint red spots on the skin
  • trembling or shaking in the hands
  • unsteadiness or awkwardness
  • unusual bleeding or bruising
  • weakness in the arms, hands, legs, or feet
  • weight loss

Some side effects of miglustat may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Back pain
  • bloated or full feeling
  • blurred or loss of vision
  • difficulty having a bowel movement (stool)
  • disturbed color perception
  • dizziness
  • double vision
  • dry mouth
  • excess air or gas in the stomach or intestines
  • halos around lights
  • headache
  • heartburn
  • heaviness in the limbs
  • indigestion
  • leg cramps
  • loss of appetite
  • memory loss
  • menstrual changes
  • nausea
  • pain or discomfort in the chest, upper stomach, or throat
  • passing gas
  • stomach discomfort, upset or pain
  • swelling of the abdominal or stomach area
  • tunnel vision
  • unsteady walk
  • vomiting

For Healthcare Professionals

Applies to miglustat: oral capsule


The most common serious side effect was peripheral neuropathy. Diarrhea and tremor were the side effects that required intervention most often.


Osmotic diarrhea appears to be due to inhibitory activity of miglustat (the active ingredient contained in Zavesca) on intestinal disaccharidases leading to reduced absorption of dietary disaccharides in the small intestine. Diarrhea decreased over time with continued therapy.

Very common (10% or more): Diarrhea (including osmotic diarrhea; up to 100%), abdominal pain (up to 67%), flatulence (up to 50%), nausea (up to 22%), vomiting (up to 11%)
Common (1% to 10%): Constipation, dry mouth, dyspepsia, epigastric pain not food-related, bloating
Frequency not reported: Dysphagia


Very common (10% or more): Weight decrease (up to 67%)
Common (1% to 10%): Anorexia

Nervous system

Very common (10% or more): Tremor/exacerbation of existing tremor (about 30%), headache (up to 22%), tremor (up to 17%), dizziness (up to 11%), leg cramps (up to 11%)
Common (1% to 10%): Unsteady gait, paresthesia, migraine, peripheral neuropathy
Frequency not reported: Gait abnormal, gait spastic, ataxia, hyperreflexia


Very common (10% or more): Generalized weakness (up to 17%)
Common (1% to 10%): Abdominal distension, back pain, heaviness in limbs, pain
Frequency not reported: Abdominal distension with gas, fatigue, lacerations


Very common (10% or more): Visual disturbances (up to 17%)


Very common (10% or more): Cramps (up to 11%)


Common (1% to 10%): Memory loss
Frequency not reported: Insomnia, decreased appetite, depression


Common (1% to 10%): Thrombocytopenia
Frequency not reported: Mild reduction in platelet count


Common (1% to 10%): Menstrual disorder


Frequency not reported: Nasopharyngitis, cough, sinusitis

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