Dexamethasone Does Not Increase Verbal Memory Score in Herpes Simplex Virus Encephalitis

FRIDAY, Jan. 30, 2026 (HealthDay News) — For adults with herpes simplex virus (HSV) encephalitis, dexamethasone plus acyclovir does not improve verbal memory score compared with acyclovir alone, but has a satisfactory safety profile, according to a study published in the February issue of The Lancet Neurology.

Tom Solomon, Ph.D., from The Pandemic Institute in Liverpool, England, and colleagues conducted a multicenter, observer-blind, randomized, phase 3 trial to examine the safety and efficacy of adjunct corticosteroids in HSV encephalitis. Adults with HSV encephalitis admitted to 53 U.K. hospitals were randomly assigned to receive intravenous dexamethasone plus intravenous acyclovir (dexamethasone group) or intravenous acyclovir alone (control group; 47 patients in each group).

The modified intention-to-treat analysis included 81 participants (39 in the treatment group and 42 in the control group). The researchers observed no significant difference in the primary outcome of verbal memory score at 26 weeks. There were 27 adverse events in 18 participants in the control group and 25 in 18 participants in the dexamethasone group (38 and 40 percent, respectively). Seizures requiring readmission to the hospital and thrombotic events were the most common serious adverse events. No treatment-related deaths occurred.

“This study shows that if you suspect a patient has encephalitis, which might be autoimmune or could be HSV, it is safe to give steroids,” Solomon said in a statement. “The fact that early corticosteroid use seems to be associated with improved outcome may well encourage doctors to do this as soon as they see the patient.”

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