Natalizumab
Tysabri (natalizumab) is a prescription monoclonal antibody used to treat relapsing forms of multiple sclerosis and moderate to severe Crohn's disease in patients who have not responded well to other therapies. It works by blocking immune cells from crossing into the brain and spinal cord, reducing inflammation and preventing immune-mediated damage.
Tysabri is an immunosuppressant monoclonal antibody used for MS and Crohn's disease that blocks immune cells from entering the central nervous system.
Key facts at a glance
- RxNorm
- 492635
- Generic
- Tysabri
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Tysabri is FDA-approved for treating relapsing forms of multiple sclerosis (including clinically isolated syndrome, relapsing-remitting MS, and active secondary progressive MS), as well as moderate to severe Crohn's disease in adults who have had an inadequate response to or cannot tolerate conventional therapies and TNF inhibitors.
Tysabri is a monoclonal antibody that binds to the alpha-4 subunit of integrins on the surface of immune cells. This prevents these cells from adhering to and crossing blood vessel walls into tissues, particularly the brain and intestines, thereby reducing inflammatory responses that contribute to disease progression.
Tysabri carries a boxed warning for progressive multifocal leukoencephalopathy (PML), a rare but serious brain infection that can be fatal. Due to this risk, it is only available through the restricted TOUCH prescribing program. Patients should be monitored for signs of infection and liver problems. Treatment may increase the risk of other infections and hypersensitivity reactions. It should not be used in combination with immunosuppressants or in patients with a history of PML.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy