Natalizumab adverse events are rare in patients with multiple sclerosis.

Objective: To assess the prevalence and the profile of adverse events (AE) of natalizumab in patients with multiple sclerosis (MS).

Methods: Data collection from neurologists attending to patients with MS at specialized units in Brazil.

Results: Data from 103 patients attending the infusion centers of 16 MS units in 9 Brazilian states were included in the study. The total number of infusions was 1,042. Seventy-nine patients (76.7%) did not present any AE. Twenty-four patients (23.3%) presented only mild AE. There were three major AE, including two deaths. These three occurrences, although not necessarily being drug-related, must be taken into consideration.

Conclusion: The profile of AEs for natalizumab shows that 97% of patients have none or only mild AE. However, still due to safety worries, the use of this medication should be restricted to MS units under the care of specialized neurologists.