Tysabri 300 mg

Tysabri increases your risk of getting a rare brain infection—called progressive multifocal leukoencephalopathy (PML)—that usually leads to death or severe disability. If PML occurs, it usually occurs in people with weakened immune systems. There is no known treatment, prevention, or cure for PML.

Your risk of getting PML may be higher if you are also being treated with other medicines that can weaken your immune system, including other treatments for MS. You should not take certain medicines that weaken your immune system at the same time you are taking Tysabri. Even if you use Tysabri alone to treat your MS, you can still get PML.