Atypical disseminated herpes zoster infections in patients with demyelinating disease treated with dimethyl fumarate.

We report two patients who developed atypical, disseminated herpes zoster infections while on dimethyl fumarate (DMF) treatment, one with varicella zoster virus (VZV) encephalitis and another with herpes zoster oticus resulting in lasting motor and sensory deficits. We recommend vaccination against VZV prior to DMF initiation be incorporated as standard of care, as ensuring patients are protected against VZV before starting DMF can prevent such severe outcomes.