Infection

Encephalitis
Antimicrobial Therapy (before prescribing, carefully read the Notes / Comments section below)

Aciclovir* IV 10mg/kg 8 hourly

*Aciclovir:

  • Use adjusted body weight (AdjBW) to calculate dose for obese patients: MDCalc AdjBW calculator
  • Obesity is defined by the National Institute for Health and Care Excellence (NICE) as BMI ≥30kg/m2. Use MDCalc BMI calculator to calculate an individual’s BMI.
  • Consult this document for further details on the required calculations.
  • More than 1000mg per dose is rarely required. Please refer to pharmacy in these circumstances.
Duration

14 days in immunocompetent individuals

21 days in immunocompromised individuals
Notes / Comments

Viral encephalitis can be caused by a variety of viral pathogens, but a specific treatment is only available for treatment of encephalitis caused by herpesviridae (Herpes simplex virus, Varicella zoster virus). 

In proven PCR-positive HSV encephalitis, repeat CSF viral PCR to confirm clearance before treatment is discontinued. 

 

 

Guideline reviewed April 2026
Page updated April 2026



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