Herpes zoster infection in a patient with relapsing-remitting multiple sclerosis treated with diroximel fumarate.

We present a case of a woman in her 50s with relapsing-remitting multiple sclerosis, treated with diroximel fumarate, who developed an itching, burning vesicular rash following a C3 dermatomal distribution on her left face and neck. She was diagnosed with herpes zoster, treated with valacyclovir and gabapentin, and made a full recovery. Ensuring patients are protected against varicella-zoster virus before starting diroximel fumarate can prevent this painful infection. Thus, we recommend vaccination against the varicella-zoster virus prior to diroximel fumarate initiation be incorporated as the standard of care.