PML - the acronym that strikes fear into the hearts of all MS patients. This is a long one but an important topic! While PML can technically be seen with many immune suppressing medication, we are most vigilant for people on Tysabri/natalizumab! For other medications rarely associated with PML, generally your doctor will order safety labs to make sure the white blood cell counts are in a safe range. PML is very rare, and there are ways to mitigate the risk. As always, discussing risks and benefi