Acute renal failure related to high doses of acyclovir (15 mg/kg/8 h) during treatment of varicella zoster virus encephalitis.

Varicella zoster virus (VZV) is less susceptible than herpes simplex virus to acyclovir. The optimal acyclovir regimen during VZV encephalitis remains unknown. We report two cases of acute renal failure after an increase in acyclovir dosage from 10 mg to 15 mg/kg/8 h during the treatment of VZV encephalitis according to French guidelines.