What Is PML?
PML Facts
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PML - or progressive multifocal leukoencephalopathy - is a devastating disease that generally leads to permanent neurological damage, severe disability, or death.
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PML is caused by reactivation of the JC virus, which is quite common in the general population but almost always kept in check by healthy immune systems.
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If a person's immune system is weakened by either disease or immunosuppressant medication, JC virus may replicate and lead to PML.​
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There is no cure for PML, and making a diagnosis is difficult.
PREVENTION is the best defense against PML.
Who is at Risk for PML
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Most PML cases today are linked to medications used to treat multiple sclerosis and a variety of cancers. A comprehensive list of PML-linked treatments can be found in the table below.
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PML can also result from immune suppression caused by HIV/AIDS, leukemias, and other immunocompromising conditions.
Medications Linked to PML

Gray shading indicates drugs with Black Box Warnings for PML in their prescribing information, the strongest warning that the FDA requires. Tables last updated on 9/16/2022. Please note that some PML-linked treatments may not be represented in these tables.