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Mepsevii Side Effects

Generic name: vestronidase alfa

Medically reviewed by Last updated on Nov 11, 2022.

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

Applies to vestronidase alfa: intravenous solution.


Intravenous route (Solution)

Anaphylaxis has occurred with vestronidase alfa-vjbk administration, as early as the first dose, therefore appropriate medical support should be readily available when vestronidase alfa-vjbk is administered. Closely observe patients during and for 60 minutes after vestronidase alfa-vjbk infusion. Immediately discontinue the vestronidase alfa-vjbk infusion if the patient experiences anaphylaxis.

Serious side effects of Mepsevii

Along with its needed effects, vestronidase alfa (the active ingredient contained in Mepsevii) 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 or nurse immediately if any of the following side effects occur while taking vestronidase alfa:


  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • cough
  • difficulty swallowing
  • dizziness
  • fast heartbeat
  • hives, itching, skin rash
  • pale skin, pain, or redness at the injection site
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rapid weight gain
  • tightness in the chest
  • tingling of the hands or feet
  • unusual tiredness or weakness
  • unusual weight gain or loss

Incidence not known

Other side effects of Mepsevii

Some side effects of vestronidase alfa 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:


  • Diarrhea
  • swelling at the injection site

For Healthcare Professionals

Applies to vestronidase alfa: intravenous solution.


The most frequently reported side effects were infusion site extravasation, diarrhea, rash, anaphylaxis, infusion site swelling, peripheral swelling, and pruritus.[Ref]


Very common (10% or more): Anti-drug antibodies developed (78%), neutralizing antibodies developed (55.6%), anaphylaxis (16.67%)[Ref]

Nervous system

Frequency not reported: Febrile convulsion[Ref]

A week 66 of treatment, 1 patient experiences a febrile convulsion during infusion of a 4 mg/kg dose. The infusion was stopped and the patient was given anticonvulsants, antipyretics, and antibiotics and the adverse reaction resolved. The patient was subsequently rechallenged without recurrence and continued on treatment with this drug.[Ref]


Very common (10% or more): Rash (25%)

Common (1% to 10%): Pruritus[Ref]


Very common (10% or more): Diarrhea (25%)[Ref]


Common (1% to 10%): Peripheral swelling[Ref]


Very common (10% or more): Infusion site extravasation (33.3%)

Common (1% to 10%): Infusion site swelling[Ref]

Frequently asked questions


1. Product Information. Mepsevii (vestronidase alfa). Ultragenyx Pharmaceutical. 2017.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.