# Safety and Tolerability
Keywords: TYSABRI, natalizumab, adverse reactions, safety, tolerability, PML, JCV, immune system disorders, hepatobiliary disorders, MedDRA

> This page provides information about the safety and tolerability of TYSABRI (natalizumab), including its adverse reactions, clinical experience, and guidance for healthcare professionals in the UK and Ireland.

## Details
- [Safety and Tolerability](#): Overview of TYSABRI's safety profile, including over 15 years of clinical experience.
- [Adverse Reactions Table](#): Detailed list of adverse reactions categorized by MedDRA system organ class.
- [StratifyJCV™](#): Information on the anti-JCV antibody test service funded by Biogen for patients on or considering TYSABRI.
- [Adverse Event Reporting](#): Guidance for reporting adverse events in the UK and Ireland, including contact details and reporting platforms.
- [References and Abbreviations](#): Definitions of key medical terms and references for TYSABRI's Summary of Product Characteristics.